Journal Papers
A parametrically excited MEMS gyroscope with optical readout: Design and simulation
Authors: Reza Gholamzadeh, Mohammadreza Salehi Moghaddam, Hassan Salarieh, Javad Akbari, Gholam Mohammad Parsanasab
Journal: Precision Engineering, Volume 96, October 2025
DOI: https://doi.org/10.1016/j.precisioneng.2025.07.027
Abstract: Design and simulation of a Micro-Opto-Electro-Mechanical (MOEMS) Gyroscope are presented. Compared to common gyroscopes, it features lower linear acceleration sensitivity and requires a lower drive voltage. The mechanical design ensures a high resonance frequency. It also has a smaller footprint and is insensitive to environmental variations. To improve shock resistance, four two-dimensional stoppers have been employed, which limit the gyroscope’s movement in two directions and increase the acceleration tolerance of the structure. Furthermore, an optical method is utilized to detect the gyroscope displacement such that the intensity of the output light is proportional to the displacement of the mechanical structure along the sense axis. A variable gap between two strip SOI waveguides modulates the output light intensity. The drive and sense mode resonance frequencies are obtained as 21.9 kHz and 22 kHz respectively; the measurement range is 
, the mechanical sensitivity is 
and the overall sensitivity is 
.
Graphene patterning without plasma etching via SU-8 pattern peel-off
Authors: Maryam Riyahi, Gholam-Mohammad Parsanasab, Mohammad Sabaeian
Journal: Nature, July 2025
DOI: https://doi.org/10.1038/s41598-025-08895-2
Abstract: Although graphene has made its way into many areas of science and technology, proper tools for patterning graphene are not available to all researchers. Therefore, any new patterning method isuseful. This research investigates the patterning of graphene layers on SiO2/Si substrates via the use of an SU-8 photoresist to produce micrometer-sized components such as electrodes. The new method is based on the sufficient adhesion of graphene to SU-8 after SU-8 cross-linking. First, SU-8 photolithography in the inverse form of the final pattern is carried out on the graphene layer. Then, both the SU-8 pattern and the graphene part attached to it are simultaneously removed, resulting in the final graphene pattern. This method can also be extended in a way that is compatible with imprint lithography, as its framework is described in this paper. In this way, the non-crosslinked SU-8 in the inverse pattern is transferred to the graphene layer via a premade stamp. This latter approach could benefit from the complete elimination of SU-8 effects, especially SU-8 contamination, from the finalgraphene pattern, as well as the simplicity of replication for mass production.
Tailoring performance through loss engineering in ring-waveguide lasers for enhanced Single-Mode lasing
Authors: Pegah Eivazy Arvanagh, Mobin Yaghoobi, Fatemeh Moradiani, Nima Nematimansur, Gholam-Mohammad Parsanasab
Journal: Optics & Laser Technology, Volume 182, April 2025
DOI: https://doi.org/10.1016/j.optlastec.2024.112116
Abstract: Loss engineering is a valuable approach for controlling the properties of ring-waveguide lasers. By carefully adjusting the waveguide’s loss parameters, it is possible to create customized lasers with improved performance for specific applications. In this study, we present the fabrication, characterization, and simulation of a ring-waveguide laser with loss-engineering capabilities. Initially, we optimized the waveguide’s cross-section to reduce scattering loss caused by side-wall roughness, achieving a low loss of 0.03 dB/cm. Next, we investigated the effect of the coupling coefficient on the lasing properties of the device by varying the gap between the waveguide and the resonator. Our experimental results demonstrate that by fine-tuning the coupling coefficient, we can achieve single-mode lasing with an impressive side-mode suppression ratio (SMSR) of over 47 dB at a wavelength of 598 nm. These findings offer valuable insights into loss-engineering techniques for ring-waveguide lasers and showcase the potential for single-mode emission lasers with high stability, which can be applied in various fields.
g
Design optimization for manufacturing polymer microring lasers: Focus on surface scattering losses
Authors: Parvin Sorayaie, Leila Hajshahvaladi, Mohammadreza Kolahdouz, Kimia Golshan, Gholam-Mohammad Parsanasab
Journal: Optics & Laser Technology, Volume 182, April 2025
DOI: https://doi.org/10.1016/j.optlastec.2024.112101
Abstract: Surface roughness scattering significantly affects the performance of microcavity lasers by influencing various design parameters. This study focuses on the design and fabrication of polymer-based microcavity lasers to achieve optimal specifications. We employed femtosecond direct laser writing on SU-8 films doped with Rhodamine B dye. Key parameters, including size, quality factor, mode volume, filling factor, and losses (bending and surface scattering), were theoretically analyzed. We specifically investigated the impact of sidewall roughness-induced scattering loss on polymer microring lasers, validating our findings through simulations and experimental characterization. Assuming a surface roughness of less than 10 nm, we designed and fabricated a single-mode double microring laser with radii of 30 µm and 32 µm, featuring a waveguide cross-sectional area of 1×2 µm2. These high-performance single-mode lasers have potential applications in optical sensing, nonlinear optics, and quantum photonics.
i
Polarization selectivity in single-mode photonic molecule lasers
Authors: Media Abbasi, Leila Hajshahvaladi, Gholam-Mohammad Parsanasab
Journal: applied physics letters, Lett. 126, February 2025
DOI: https://doi.org/10.1063/5.0252413
Abstract: An efficient approach to achieve single-polarization selectivity in single-mode double microring lasers (photonic molecule lasers) is presented in this study. The fabricated microring lasers achieved polarization extinction ratios of 11.3 dB for TM polarization and −12.8 dB for TE polarization. The fabrication process was conducted by direct laser writing on SU-8 photoresist doped with Rhodamine B dye. In order to obtain an optimum single-mode operation with a specified polarization capability, the study employs Vernier effect double microring lasers and investigates the effects of geometric characteristics, surface scattering loss, and coupling efficiency on polarization performance. The finite-difference time-domain method was utilized to conduct simulations, and the results were verified experimentally. The proposed single-polarized microring lasers provide open possibilities for advanced integrated photonic systems with potential applications in quantum photonics, nonlinear optics, and optical sensors.
i
g
g
Efficient multilayer near-infrared micro-bottle laser pumped by a 532 nm nanosecond laser
Authors: Parvin Sorayaie, Mohammadreza Kolahdouz, Zahra Baghbani Tehrani, Leila Hajshahvaladi, Media Abbasi, Farzad Batoomchi, Gholam-Mohammad Parsanasab
Journal: Nature, 15, Article number:6034, February 2025
DOI: https://doi.org/10.1038/s41598-025-90629-5
Abstract: This paper explores the development and optimization of organic near-infrared micro-cavity lasers for biophotonic applications. Four micro-bottle laser configurations inclouding single-layer, two-layer, and three-layer structures were designed and fabricated using Nile-Blue (NB) and Rhodamine B (RhB) laser dyes doped in SU-8 polymer as laser-active materials. While NB achieves lasing near 750 nm, its absorption of common pump sources such as Nd: YAG lasers at 532 nm is limited. Therefore, Forster resonance energy transfer (FRET) between RhB and NB was employed to enhance NB’s lasing efficiency under 532 nm excitation. Experimental and simulation results demonstrate that multilayer designs, particularly the three-layer configuration, outperform others, achieving higher emission intensity, improved stability, and reduced lasing thresholds. The inclusion of RhB optimizes pump absorption and enables efficient energy transfer, facilitating stable Near-IR lasing at 720–750 nm. These findings highlight the potential of multilayer micro-cavity lasers for compact, efficient, and stable organic laser systems in biophotonic and sensing applications.
o
Observation of anti-PT-symmetry and higher-order exceptional point PT-symmetry in ternary systems for single-mode operation
Authors: Milad Jahangiri, Gholam-Mohammad Parsanasab, Leila Hajshahvaladi
Journal: Nature, 15, Article number:4823, February 2025
DOI: https://doi.org/10.1038/s41598-025-85623-w
Abstract: Nowadays, topological parity-time (PT) and anti- parity-time (APT) symmetry systems have attracted substantial attention due to their noticeable features and specific applications. The emergence of exceptional points in these systems plays a direct role in their overall responses and causes them to exhibit an entirely real spectrum. Here, we propose and analyze a new approach based on the broken PT in the vicinity of a third-order exceptional point and APT symmetry that allows us to experimentally achieve a stable single-mode laser. A feasible third-order exceptional point can be synthesized by coupling three microcavities to each other. The behaviors of these lasers are evaluated in different situations according to introducing the gain and loss perturbation to the system. Our proposed microlasers and their distinct properties based on photonic exceptional points may find use in a wide variety of applications such as ultrahigh precision sensing, spectroscopy, and optical on-chip filters and lasers.
v
Highly Efficient DFB Laser-Assisted Grating As2S3 Chalcogenide for Integrated Photonics
Authors: Afshin Mafakheri, Gholam-Mohammad Parsanasab, Parvin Sorayaie, Samaneh Mostajeran, Ladan Akbari, Mohammadreza Kolahdouz
Journal: IEEE, Journal of Lightwave Technology, Volume 42, Issue 14, 15 July 2024
DOI: https://doi.org/10.1109/JLT.2024.3381647
Abstract: Chalcogenide (As2S3) is a material with promising applications in integrated photonics. This material has the potential for low-threshold, compact, and high-coherence light sources. Our team has developed a chalcogenide-based distributed feedback (DFB) laser using a ridge polymer waveguide structure, incorporating a 500 nm As2S3 grating as the wavelength selective element. With precise engineering of the DFB laser structure, we have achieved single-mode lasing with an 18 nJ lasing threshold and a side mode suppression ratio (SMSR) of 28 dB. Additionally, we have found that the single-mode lasing persists over a wide range of pump power energy. To validate our experimental results, we performed a numerical simulation of the proposed structure, which confirmed experimental results.
c
Carbon Quantum Dot Embedding Silica–Molecularly Imprinted Polymer Coated Optical Fiber as Ratiometric Biosensors Toward Dopamine Detection
Authors: Tahereh Azargoshasb, H. Ali Navid, Sajjad Yadollahzadeh, Reza Aghbolaghi, Roghaieh Parvizi, Gholam-Mohammad Parsanasab
Journal: IEEE, IEEE Sensors Journal, VOL. 24, NO. 4, 15 FEBRUARY 2024
DOI: https://doi.org/10.1109/JSEN.2023.3347262
Abstract: We have developed a ratiometric fluorescence sensor for detecting dopamine (DA) using a silica-based molecular imprinting polymer (MIP) coated on cabbage-derived blue emissive carbon quantum dot (CQD) and deposited on optical fiber. Physicochemical characterization confirmed the successful integration of MIP and CQD, which created the selective lossy mode resonance (LMR) for DA monitoring. The experimental factors were optimized to obtain the maximum responses, and the sensing probe displays a dynamic response range of 0.3– 100μm and detection limit 0.027μm . This strategy was successfully applied to detect DA in red wine, coffee, apple, orange, and broad bean juices samples, with negligible cross-reactivity toward other potential interfering species (e.g., epinephrine, ascorbic acid, and uric acid). This novel rotational optical fiber-based sensor has promising potential and versatility for point-of-care, portable, and on-site sensing of environmental and biological samples.
J
J
Wavelength-Selective Single-Mode Laser by Joint Use of Parity-Time Symmetry and Vernier Effect in Symmetric and Asymmetric Coupled Microrings
Authors: Milad Jahangiri, Gholam-Mohammad Parsanasab, Fatemeh Moradiani
Journal: IEEE, Journal of Lightwave Technology, Volume 42, March 2024
DOI: https://doi.org/10.1109/JLT.2023.3324226
Abstract: The Control of the gain and loss in microcavities, especially microrings, and discs, plays a crucial role in harnessing the excited modes in these types of microlasers. In multi-microring configurations, the Vernier effect eliminates various excited modes within the system, while simultaneously strengthening and producing many latitudinal modes. The implementation of the spectral Vernier effect involves the utilization of two coupled asymmetric microrings to enhance the effective free spectral range (FSR). By carefully balancing the gain/loss ratio and breaking parity-time symmetry, these latitudinal modes can be extensively suppressed, resulting in the single-mode lasing operation. Here, we have successfully demonstrated that wavelength-selective single-frequency lasing can be achieved in structures consisting of two coupled size-mismatched microrings by simultaneously employing the Vernier effect and broken parity-time (PT) symmetry. By controlling the gain/loss ratio through pump variations, the gain can adapt to changes in single-mode lasing wavelength, while the loss effectively suppresses numerous excited modes, leaving only a dominant mode. Thanks to gap engineering, the single-mode lasing based on broken parity-time symmetry at different wavelengths occurs by changing the air gap between two symmetric microrings. The proposed structures have been thoroughly analyzed both experimentally and numerically. Our findings can contribute to a deeper understanding of the spectral modulation process in coupled microrings lasers, offering valuable insights for future research in this field.
g
An investigation on the effects of geometrical parameters on the sensitivity of micro-disk and micro-ring plasmonic sensors
Authors: M. Amin Khanpour, Fatemeh Moradiani, Gholam-Mohammad Parsanasab, R. Karimzadeh
Journal: Optics & Laser Technology, Volume 162, July 2023, 109236
DOI: https://doi.org/10.1016/j.optlastec.2023.109236
Abstract: Geometrical parameters of coupled plasmonic resonators that consist of micro-disk and micro-ring structures have been investigated numerically, and changes in the Q factor, mode volume, and Purcell coefficient of the investigated structure have been calculated according to changes in geometrical variables. Optimal geometrical values for achieving plasmonic modes have been found using simulation results. Additionally, the performance of a single micro-disk, the single micro-ring, and two coupled micro-ring structures as a refractive index sensor has been compared and reported. It has also been shown that although the general shape of the figure of merit (FoM) graph is the same for all tested structures, the FoM of the disk resonator achieves lower values compared to ring and coupled resonators.
g
Single-mode lasing by tailoring the excitation of localized surface plasmon resonances to whispering gallery modes in a microring laser
Authors: Fatemeh Moradiani, Pegah Eivazy Arvanagh, Gholam-Mohammad Parsanasab, Alireza Kavosi
Journal: Optics Express, 2023 May
DOI: https://doi.org/10.1364/oe.480355
Abstract: Cavity mode manipulation in lasers is urgent for the stable single-mode operation of a microring laser. Here, we propose and experimentally demonstrate the plasmonic whispering gallery mode microring laser for strong coupling between local plasmonic resonances and whispering gallery modes (WGM) on the microring cavity to achieve pure single-mode lasing. The proposed structure is fabricated based on integrated photonics circuits consisting of gold nanoparticles deposited on a single microring. Additionally, our numerical simulation provides deep insight into the interaction between the gold nanoparticles and WGM modes. The manufacture of microlasers for the advancement of lab-on-a-chip devices and all-optical detection of ultra-low analysts may benefit from our findings.
d
d
High side-mode suppression ratio with a Vernier effect single-mode laser using triple coupled microrings
Authors: Milad Jahangiri, Fatemeh Moradiani, Gholam-Mohammad Parsanasab, Mohsen Mirmohammadi
Journal: Nature, 13, Article number:7092, May 2023
DOI: https://doi.org/10.1038/s41598-023-34267-9
Abstract: The development of single-mode lasers with a high side-mode suppression ratio (SMSR) is challenging but highly desirable for integrated photonics devices and long-distance communications due to their high spectral purity and stability. Here, we demonstrate a single-mode laser with a high side-mode suppression ratio based on size-mismatched triple-coupled microrings. With the exact engineering of several key parameters of the structure like air gap and radii of microrings for controlling the free spectral range (FSR), a predominant mode is selected to lase in amplified spontaneous emission (ASE) of the gain material and all side and high order modes are suppressed by Vernier effect. In this work, we show that a single-mode operation is efficiently generated with an improved side-mode suppression ratio of over 20 dB in a three-ring-coupled microcavity laser. The single-frequency output persists for a wide power range. The theoretical calculations and numerical simulations’ results confirm the validity of the experimental results. Our structural engineering creates new opportunities in a variety of frontier applications in single-mode lasers and high-quality sensors.
g
g
j
Design and Fabrication of a Differential MOEMS Accelerometer Based on Fabry–Pérot Micro-Cavities
Authors: Mojtaba Rahimi, Mohammad Malekmohammad, Majid Taghavi, Mohammad Noori, Gholam-Mohammad Parsanasab
Journal: IEEE Sensors Journal, Volume 22, August 2022
DOI: https://doi.org/10.1109/JSEN.2022.3184979
Abstract: In this paper, a differential micro-opto-electro-mechanical system (MOEMS) accelerometer based on the Fabry-Pérot (FP) micro-cavities is presented. The optical system of the device consists of two FP cavities and the mechanical system is composed of a proof mass that is suspended by four springs. The applied acceleration tends to move the PM from its resting position. This mechanical displacement can be measured by the FP interferometer formed between the proof mass cross-section and the optical fiber end-face. The proposed sensor is fabricated on a silicon-on-insulator wafer using the bulk micromachining method. The results of the sensor characterization show that the accelerometer has a linear response in the range of ±1g . Also, the optical sensitivity and resolution of the sensor in the static characterization are 6.52 nm/g and 153μg . The sensor sensitivity in the power measurement is 49.6 mV/g and its resonant frequency is at 1372 Hz. Using the differential measurement method increases the sensitivity of the accelerometer. Based on the experimental data, the optical sensitivity in static mode is two times as high as that of a similar MOEMS accelerometer with one FP cavity.
g
Closed-loop MOEMS accelerometer
Authors: Majid Taghavi, Abolfazl Abedi, Gholam-Mohammad Parsanasab, Mojtaba Rahimi, Mohammad Noori, Hamzeh Nourolahi, Hamid Latifi
Journal: Optics Express, Volume 30, June 2022
DOI: https://doi.org/10.1364/OE.455772
Abstract: In this paper, a closed-loop micro-opto-electro-mechanical system (MOEMS) accelerometer based on the Fabry-Pérot (FP) interferometer is presented. The FP cavity is formed between the end of a cleaved single-mode optical fiber and the cross-section of a proof mass (PM) which is suspended by four U-shaped springs. The applied acceleration tends to move the PM in the opposite direction. The arrays of fixed and movable comb fingers produce an electrostatic force which keeps the PM in its resting position. The voltage that can provide this electrostatic force is considered as the output of the sensor. Using a closed-loop detection method it is possible to increase the measurement range without losing the resolution. The proposed sensor is fabricated on a silicon-on-insulator wafer using the bulk micromachining method. The results of the sensor characterization show that the accelerometer has a linear response in the range of ±5 g. In the closed-loop mode, the sensitivity and bias instability of the sensor are 1.16 V/g and 40 µg, respectively.
A high sensitive, low foot print, SU-8 material-based, light intensity modulated MOMS accelerometer
Authors: Reza Gholamzadeh, Hassan Salarieh, Gholam Mohammad Parsanasab, Javad Akbari
Journal: Optical Engineering, Volume 61, May 2022
DOI: https://doi.org/10.1117/1.OE.61.5.055103
Abstract: A high sensitive optical MEMS accelerometer is proposed, which works by changing the effective refractive index of a microring relied on intensity modulation of light wave. The proposed optical sensing system consists of a microring, waveguide, and a proof mass. Acceleration causes lateral displacement of the proof mass. The proof mass is in the optical coupling length of the microring, and the displacement of the proof mass changes effective refractive index of the microring. Changes of the effective refractive index of the microring result in wavelength shift. The mechanical and optical parts of the proposed accelerometer are designed, and the obtained functional characteristics are compared with other accelerometers. Simulation shows functional characteristics of the proposed design are as follows: mechanical resonant frequency of 3.7 kHz, operating bandwidth of 2.6 kHz, mechanical sensitivity of 2 nm/g, optical sensitivity of 0.7%/nm, overall sensitivity of 1.4%/g, foot print of less than 150 μm * 170 μm, measurement range of ∓ 50 g, and mechanical noise density of 3.1 ( mg / Hz ) . These functional characteristics make the design very interesting for a wide range of applications, ranging from consumer electronics and automobile to inertial navigation.
Sensors and Actuators: B. Chemical
Authors: Tahereh Azargoshasb, Roghaieh Parvizi, H. Ali Navid, Gholam-Mohammad Parsanasab, Hadi Heidari
Journal: Sensors & Actuators, 2022
DOI: https://doi.org/10.1016/j.snb.2022.132551
Abstract: A versatile lossy mode resonance (LMR) sensor is developed for Epinephrine monitoring based on the state-of-the-art molecular imprinting technique over an optical fiber. The optical absorption concept of the LMR-based sensor is proven by incorporating an amino silane-functionalized graphene oxide (SiO2-NH2@GO) as an adhesive layer for grafting Epinephrine imprinting polydopamine (Ep-IPDA) as a sensing layer onto the optical fiber curved surface. The accurate structural and morphological characterization confirmed the rough crystalline and spherical particles for Ep-IPDA and SiO2-NH2-GO onto optical fiber curved surface, while spectroscopic analysis confirms the formation of imprinting polymer and desirable absorbance characteristics. The optimized probe exhibits an excellent performance with the maximum sensitivity within two intervals of 0.3–1 µM and 1–90 µM along with the linearity coefficient of R2 = 0.99 possessing a low limit of detection of 0.07 µM. Additionally, this sensor selectively detects Ep in the presence of other species and showed good recovery in human urine and injection samples. This work opens a new avenue for developing bio-inspired LMR-based optical fiber biosensors and could be further extended to detect other catecholamine neurotransmitters.
k
Optical Fiber Biosensor toward E-coli Bacterial Detection on the Pollutant Water
Authors: Hoorieh Fallah, Tannaz Asadishad, Gholam M. Parsanasab, Sulaiman Wadi Harun, Waleed S. Mohammed, Moh. Yasin
Journal: Engineering Journal, December 2021
DOI: https://doi.org/10.4186/ej.2021.25.12.1
Abstract: In this study, Zinc oxide (ZnO) nanorods based fiber optic biosensor has been reported for rapid and sensitive detection of Escherichia Coli (E coli). A thin layer of Gold nanoparticles (Au) (around 50 nm) is coated on the tip of a multimode plastic optical fiber. ZnO Nanorods are grown on Au layer thorough hydrothermal technique. This sensor showed a very fast response within the first 10 second of contacting the present of polluted water with E-coli Different concentrations of E. coli from (1000 to 4000 CFU/ml) have been tested and a sharp trend of sensitivity was observed. This sensing platform shows promising potential for regular water and food quality monitoring of various pathogenic microorganisms.
l
A Dual-Axis MOEMS Accelerometer
Authors: Majid Taghavi, Hamid Latifi, Gholam Mohammad Parsanasab, Abolfazl Abedi, Hamed Nikbakht, Mohammad Hosein Poorghadiri
Journal: IEEE Sensors Journal, Volume 21, June 2021
DOI: https://doi.org/10.1109/JSEN.2021.3072333
Abstract: This paper is a report on the design and fabrication of a dual-axis micro-opto-electro-mechanical system (MOEMS) accelerometer. The device consists of a proof mass (PM) suspended by four L-shaped springs. Two Fabry-Pérot (FP) cavities are formed between the cross-sections of the PM and the ends of two cleaved optical fibers in perpendicular directions (the X and Y axes). The acceleration causes the proof mass to move in the reverse direction relative to the applied acceleration. The sensor is fabricated by a silicon-on-insulator wafer. The fabricated sensor is characterized both by spectral monitoring and power measurements in the range of ±1 g. The results of spectral measurements show 3.23 nm/g (g = 9.81 m/s2: gravity constant) and 3.19 nm/g to the applied acceleration along the X and Y axes, respectively. Moreover, the obtained resolutions for the two directions of X and Y are 309 μg and 313 μg , respectively. Besides, the sensitivity of the sensor in power measurements is 550 mV/g and 528 mV/g in the X and Y directions, respectively. The sensor also possesses the resonant frequencies of 1382.5 Hz and 1398.6 Hz in the X and Y axes, respectively, in the range of ±1 g. The maximum cross-axis sensitivities obtained for this sensor are below 0.19% for each pair of X, Y, and Z axes. This value is fewer than the cross-axis sensitivity of most micro electro-mechanical systems without any post processing. This small value is a result of insensitivity of the FP spectrum to the lateral displacements of the PM.
k
k
A high extinction ratio plasmonic SU-8 waveguide polarizer
Authors: Peyman Malekzadeh, Gholam-Mohammad Parsanasab, Hamed Nikbakht, Ezeddin Mohajerani, Majid Taghavi, Hamid Latifi
Journal: Optics Communications, Volume 487, May 2021
DOI: https://doi.org/10.1016/j.optcom.2021.126798
Abstract: In this paper, a novel method has been proposed for increasing the extinction ratio of a plasmonic waveguide polarizer. Aluminum was coated in a 20-micron multi-strip pattern on the top of a SU-8 waveguide to excite the surface plasmons. The simulation and experimental results showed that the extinction ratio of the multi-strip polarizer was more than those of single strip polarizers with the same total aluminum-coated length due to the coupling loss between the Al-coated and uncoated regions and also the scattering at the edge of metal. This polarizer was characterized over a wide range of wavelengths and showed the high extinction ratios of 46 dB and 26.8 dB at the wavelengths of 1550 nm and 980 nm, respectively.
j
k
k
Utilizing polarization-selective mode shaping by chalcogenide thin film to enhance the performance of graphene-based integrated optical devices
Authors: Hamed Nikbakht, Hamid Latifi, Gholam-Mohammad Parsanasab, Majid Taghavi, Maryam Riyahi
Journal: Nature, August 2019
DOI: https://doi.org/10.1038/s41598-019-48890-y
Abstract: High refractive index (RI) thin films are capable of pulling waveguide mode profiles towards themselves. In this study, it is shown that by applying high RI coatings with specific thicknesses on the side of optical waveguides, significantly different mode profiles for orthogonal polarizations can be achieved. This phenomenon, that we call it polarization-selective mode shaping, can be extensively used in the enhancement of polarization-dependent integrated optical devices. As an illustrating application, a tri-layer structure consisting of poly(methyl methacrylate)/graphene/chalcogenide on a side-polished fiber is designed to realize an extremely high extinction ratio polarizer. This structure changes the mode profiles in a way that the attenuation of TE mode is maximized, while the power carried by the TM mode remains relatively constant. Simulations and experimental characterizations confirm that polarization-selective mode shaping coordinates four loss mechanisms to maximize the extinction ratio and minimize the insertion loss of the polarizer. The fabricated polarizer is examined in the O, C, and L telecommunication frequency bands. This configuration achieves the high extinction ratio of 51.3 dB and its maximum insertion loss in the tested wavelengths is 1.79 dB. The proposed polarizer has been compared with other state-of-the-art polarizers in the conclusion section which shows its superiority.
Investigation of a High-Power Low-Threshold Single-Mode Microsphere Laser Using a Serially Coupled Double Microsphere Structure
Authors: Marzieh Saffari, Asghar Gholami, Gholam-Mohammad Parsanasab, Zaker Hossein Firouzeh
Journal: IEEE, Journal of Lightwave Technology, Volume 37, July 2019
DOI: https://doi.org/10.1109/JLT.2019.2913901
Abstract: A high-power narrow-linewidth low-threshold single-mode microsphere laser is investigated by coupling an undoped microsphere with a different size to a single-microsphere laser. A model is proposed for microsphere lasers and it is verified by comparing its results to the experimental results published in the literature for a thulium-doped tellurite glass single 12.5-μm microsphere laser. It is illustrated that by coupling an 11.5-μm undoped microsphere to a multimode 50-μm thulium-doped tellurite glass microsphere laser, a single-mode operation is obtained, and despite the relatively high output power, the quality factor also remains high. For the proposed structure, an output power of 208 μW at 30-mW pump power is achieved. Its threshold power and full width at half maximum linewidth are 0.06 mW and 0.53 fm (40 kHz), respectively, which are significantly enhanced compared to the single 12.5-μm microsphere laser.
f
Random lasing emission from FTO and glass substrates coated with dye doped SU-8 epoxy based polymer
Authors: Peymaneh Rafieipour, Abbas Ghasempour Ardakani, Gholam-Mohammad Parsanasab
Journal: Optics & Laser Technology, Volume 119, November 2019
DOI: https://doi.org/10.1016/j.optlastec.2019.105602
Abstract: The demand for improving dyeing efficiency and photochemical/photo-physical properties of organic-dyes-based random lasers while focusing on eco-friendly procedures, cost effective production and reduced toxicity has been grown for the past few years. In order to fulfill these requirements, an organic dye dissolved in the solution of SU-8 polymer is proposed as the gain medium in a typical random laser structure. Considering adhesion properties of the SU-8 resin, we observe random lasing action in a glass substrate and also fluorine doped tin oxide (FTO) layer covered by the solution of rhodamine B dye doped SU-8 polymer. Line-width narrowing and drastic increase of the emitted intensity confirm the onset of random lasing emission in the proposed structures. When we use alcohol solution as the dye solvent instead of SU-8 polymer, no random laser emission is observed in these structures. It is also shown that due to larger grains of the FTO substrate compared to the roughness of the glass substrate, RL emission occurs more efficiently in the FTO substrate. Obtained results may stimulate facile fabrication of cost effective, intensive and low threshold RLs based on dye doped SU-8 polymer as the gain medium.
f
Simulation, Fabrication, and Characterization of a Sensitive SU-8-Based Fabry-Pérot MOEMS Accelerometer
Authors: Majid Taghavi, Hamid Latifi, Gholam-Mohammad Parsanasab, Abolfazl Abedi, Hamed Nikbakht, Mohammad Javad Sharifi
Journal: IEEE, Journal of Lightwave Technology, Volume 37, MAY 2019
DOI: https://doi.org/10.1109/JLT.2019.2894752
Abstract: This paper presents the design, fabrication, and characterization of a SU-8 four L-shaped beams optical micro-electro-mechanical-system accelerometer based on a Fabry–Pérot (FP) interferometer. An applied acceleration causes a displacement of the proof mass and changes the cavity of FP resonator. Fabrication process has been simplified such that only two photolithography steps are required and SU-8 is used for both the structural body and the sacrificial layer. To prevent the sacrificial layer from being exposed to UV light, a thin copper layer is coated by physical vapor deposition technique between the two SU-8 layers. The sensor chip consists of a proof mass which is suspended by four L-shaped springs. The movement of the proof mass in response to acceleration is detected by a FP cavity formed between the proof mass and the cleaved end of a single mode optical fiber. The fabricated sensor has a sensitivity of 12.5 μW/g and resonant frequency of 1872 Hz in the range of ±1 g.
G
Efficient Er:Ti:LiNbO3 Ridge Waveguide Amplifier by Patterning As2S3 Layer
Authors: Keyvan Ahmadi, Abdolnasser Zakery, Gholam-Mohammad Parsanasab
Journal: Applied Physics B, 125, May 2019
DOI: https://doi.org/10.1007/s00340-019-7199-7
Abstract: In this study, the effect of As2S3 waveguide layer on propagation gain for Er:Ti:LiNbO3 ridge waveguide amplifiers is investigated. In comparison with a typical titanium in-diffused channel waveguide, the three side Erbium in-diffusion of a 6 μm wide ridge waveguide and the better light confinement has improved the overlap between Er concentration and guided mode profiles up to 2.58 times. Our simulation demonstrates that by purposely adjusting the thickness of the three side As2S3 layer it is possible to pull the guided mode towards the ridge/air interface where Er concentration is higher. Consequently in this new configuration by taking advantage of the high refractive index As2S3 layer and mode de-shaping, the overlap relative to a ridge free of As2S3 layer has increased by 1.5 times thereby gain coefficient has been improved from 3.2 to 4.28 dB/cm at a coupled pump power of 200 mW. In comparison with a typical Ti channel waveguide amplifier, the relative overlap has increased by 3.88 times resulting in noticeable gain improvement from 0.65 to 4.28 dB/cm under the same Er diffusion conditions.
Synthesis and Characterization of Soluble Aromatic Polyesters with Side-Chain Azobeneze and Azothiazole Chromophores
Authors: Shadi Asgari, Gholam Ali Koohmareh, Gholam-Mohammad Parsanasab
Journal: Polymer Science, Volume 60, May 2018
DOI: https://doi.org/10.1134/S156009041802001X
Abstract: The paper presents the synthesis of a series of polyesters containing nitro-substituted phenyl azothiazole, azobenzothiazole and azobenzene chromophores and their characterization by 1H NMR, FTIR and UV–Vis spectroscopy. Also the solubility, glass transition temperatures, thermal stability of the synthesized polyesters as well as the surface morphology of thin films of the polyesters were studied.
h
h
Femtosecond laser direct writing of single mode polymer micro ring laser with high stability and low pumping threshold
Authors: Gholam-Mohammad Parsanasab, Mojtaba Moshkani, Alireza Gharavi
Journal: Optics Express, Volume 23, March 2015
DOI: https://doi.org/10.1364/OE.23.008310
Abstract: We have demonstrated an optically pumped polymer microring laser fabricated by two photon polymerization (TPP) of SU-8. The gain medium is an organic dye (Rhodamine B) doped in SU-8, and the laser cavity is a double coupled microring structure. Single mode lasing was obtained from the two coupled rings each with 30 µm and 29 µm radii using Vernier effect. Low laser threshold of 0.4 µJ/mm2 is achieved using 1 µm wide polymer waveguides and the quality factor is greater than 104 at 612.4 nm wavelength. The lasing remained stable with pump energies from threshold to energies as high as 125 times the threshold.
Growth of a seven pointed star shaped of vertical and uniform ZnO nanostructures on optical fiber via catalyst-free VLS mechanisms
Authors: Parvin Sorayaie, Mohammad-Hasan Yusefi, Hamid-Reza Fallah, Gholam-Mohammad Parsanasab
Journal: Applied Physics A, Volume 118, November 2014
DOI: https://doi.org/10.1007/s00339-014-8884-3
Abstract: In this paper, the growths of ZnO nano- and microstructures by VLS mechanism have been studied. A piece of silica fiber (SMF-28 optical fiber) was used as a substrate. By controlling the experimental conditions, nano- and microstructures of ZnO with different shapes and sizes were grown around the optical fiber, which can be used as an optical fiber sensor. A star-shaped ZnO microstructure was obtained in this research. Pyramidal structures were grown on each side of vertical hexagonal microrods which formed the seven-pointed star-shaped microstructures. This growth process was carried out in a special quartz container in a tube furnace at temperatures around 400–550 °C without any additional catalyst. XRD, SEM and PL spectroscopy were used for the characterization of the produced nanostructures. The influence of temperature, reactant and carrier gases flow rate on the morphology of ZnO nanostructure was investigated.
k
Fabrication of tapers with Gaussian refractive-index profile in azo polymers
Authors: Khadije Miar-Abas-Kiani, Gholam-Mohamad Parsanasab, Alireza Gharavi
Journal: Applied Physics B, Volume 111, February 2013
DOI: https://doi.org/10.1007/s00340-013-5352-2
Abstract: We have fabricated a refractive-index-tapered waveguide by exposing an azo polymer film to a 532-nm wavelength laser beam focused to about 60-μm spot size at the film with no surface deformation. The converging ability of the taper (ability to increase intensity along the taper) was measured to be 5 db/cm while the loss was 0.39 db/cm. According to the data obtained, the power density increases along the taper while loss is nearly constant along the tapered and non-tapered segments.
l
Integrated Polymeric All-Optical Switch
Authors: Gholam-Mohammad Parsanasab, Hamid Reza Karimi-Alavijeh, Soheil Soltani, Alireza Gharavi
Journal: IEEE, Journal of Lightwave Technology, Volume 29, September 2011
DOI: https://doi.org/10.1109/JLT.2011.2163381
Abstract: An all-optical switch was fabricated using azo polymers in a directional coupler form where the index of the coupling region was change via cis-trans of azo dyes in the polymer matrix. Exposing the coupling region to green or violet light caused switching action with a response time of about 10 second.
h
h
h
Two-dimensional photonic crystal for optical channel separation in azo polymers
Authors: Hamidreza Karimi-Alavijeh, Gholam-Mohammad Parsanasab, Mohammad-Amin Baghban, Alireza Gharavi
Journal: Applied Optics, Volume 48, June 2009
DOI: https://doi.org/10.1364/AO.48.003250
Abstract: We have fabricated a two-dimensional photonic crystal that functions as a two-channel add/drop filter on azo-functionalized polymeric films using a fast, direct-writing method. By properly adjusting the resonance, this structure can be used as a multichannel add/drop filter in the plane of the film. Here, we were able to separate two channels at 1555.7 and 1570.7 nm with attenuation of 13.1 dB and FWHM of 6.7 nm for each channel. The separated channels were directed towards the sides at an approximately 90° angle
Add/drop filter using in-plane slanted gratings in azo polymers
Authors: Hamidreza Karimi-Alavijeh, Mohammad-Amin Baghban, Gholam-Mohammad Parsanasab, Edris Sarailou, Alireza Gharavi, Sirus Javadpour
Journal: Optics Letters, Volume 33, September 2008
DOI: https://doi.org/10.1364/OL.33.002152
Abstract: We have fabricated in-plane slanted gratings on azo-functionalized polymeric films using a fast, directwriting method. By properly adjusting the resonance, these gratings can be used as 90° integrated reflectors and add/drop filters in the plane of the film. We have produced an attenuation of 14.8 dB at 1560.2 nm with a FWHM of 6.47 nm. Also, a signal of 1548 nm wavelength was added to the output from a different direction. Any light shifted from the resonance will pass through the filter undisturbed.
k
Fabrication of graded index waveguides in azo polymers using a direct writing technique
Authors: Hamidreza Karimi–Alavijeh, Gholam-Mohammad Parsanasab, Mohammad-Amin Baghban, Edris Sarailou, Alireza Gharavi, Sirus Javadpour, Vladimir Shkunov
Journal: Applied Physics Letters, Volume 92, January 2008
DOI: https://doi.org/10.1063/1.2838341
Abstract: Fast direct writing of waveguides on polymers using low power continuous wave lasers has been investigated. Using the cis-trans property of a functionalized sulfonated azo chromophores, we have fabricated graded index waveguides with low loss, which is due to graded index sidewalls. Fabrication is done by exposing the polymer film to a 532 nm wavelength laser beam focused to about 5 μm spot at the film. Losses were calculated to be 0.48606±04 dB/cm at 830 nm wavelength with no surface deformation. This technique enables us to fabricate integrated optical circuits including directional couplers, dividers, filters, switches, etc., as they are currently investigated in our laboratory.
l
Fabrication of 2-D photonic crystals using azo polymers
Authors: Alireza Gharavi, Hamidreza Karimi-Alavijeh, Edris Sarailou, Mohammad Amin Baghban, Gholam-Mohammad Parsanasab
Journal: International Journal of Optics and Photonics, Volume 2 ,January 2008
DOI:
Abstract: In this paper, we have reported the fabrication of two-dimensional photonic crystals, using a direct writing method in azo polymers. Periodic structures have been fabricated using the interference patterns of two coherent laser beams. The frequency response of the initial one-dimensional structure shows an attenuation of 19.3dB at 1554nm. The twodimensional structure shows 8.3dB and 11.3dB of attenuation at 1554nm in two perpendicular main axes of the structure. The diffraction pattern shows the characteristic rectangular pattern.
Conference Paper
Photonic Quantum Approximate Optimization Algorithm for Solving Max-Cut Problem
Authors: Sarah Daneshzad, Gholam-Mohammad Parsanasab, Seyyed Mohammad Hassan Halataei
Conference: The Annual Physics Conference of Iran, October 2025
Abstract: We present an original implementation of the Quantum Approximate Optimization Algorithm (QAOA) on a photonic quantum computing platform to solve a combinatorial optimization problem (Max-Cut). We adapt QAOA to CV photonic hardware via Xanadu’s software suite. We encode problem variables into optical modes (single-rail qubits) and employ photonic quantum gates (including squeezers, beamsplitters, phase shifts, and effective Kerr-type interactions) to construct the QAOA cost and mixer Hamiltonians. The algorithm was experimentally tested through simulations and partial runs on Xanadu’s X8 photonic quantum processor. We report successful optimization of a small graph’s cut, with the photonic QAOA state converging to high-quality solutions. Real photonic hardware trials showed output distributions biased toward the optimal cut assignments, in agreement with simulation.
j
Design and Analysis of High-Efficiency Silicon Nitride Waveguide Grating Coupler
Authors: Seyed Sobhan Hosseini Hajibekandeh, Leila Hajshahvaladi, Gholam-Mohammad Parsanasab
Conference: ICOP, ICPET, February 2025
Abstract: his paper presents an optimized design for grating couplers (GCs), which are essential in photonic circuits for efficient light coupling between optical fibers and waveguides. Achieving high coupling efficiency is crucial for compact photonic devices, where minimizing losses is paramount. We proposed a Si3N4-based grating coupler design that employs precise tuning of the grating period, refractive index, and incident angle, guided by the Bragg condition, to maximize efficiency at a target wavelength of 1550 nm. The resulting structure achieves a high coupling efficiency of 48% at an 8-degree incident angle. A proposed designed transition taper with an efficiency of approximately 97% facilitates smooth mode transition with minimal scattering and power loss, further enhancing overall performance. This work highlights the importance of meticulous parameter control in advancing GC efficiency and supporting the development of highperformance, compact photonic circuits.
Investigation and Measurement of Polarization-Dependent Scattering Loss on the Slab Waveguide Surface
Authors: Media Abbasi, Leila Hajshahvaladi, Gholam-Mohammad Parsanasab
Conference: International Conference on Quantum Technologies & Industrial Applications, May 2024
Abstract: In this paper, we investigate and measure the loss of TE (transverse electric) and TM (transverse magnetic) polarized modes induced by light scattering on the surface of the slab waveguide. This scattering is induced by the coupling of light from a prism into the SU-8 film at a specific angle. To measure the loss, we employed an optical fiber that was coupled from the top of the light line to the film. Therefore, we scanned the light scattering using an optical fiber and transmitted the results to the detector for calculating the loss induced by light scattering. The measured loss causes by surface scattering for TE and TM modes in the slab waveguide is 0.32 dB/cm and 0.23 dB/cm, respectively. The measured and simulated results are matching up to 70%.
Optimization of Coupling Between a Tapered Optical Fiber and a Polymer-Based Optical Waveguide
Authors: Mahtab Hossein-Alizadeh, Mona Soraya, Gholam-Mohammad Parsanasab, Shokrollah Karimian
Conference: ICEE, May 2024
Abstract: In this study, to increase the overlap between the modes inside the fiber and the waveguide, a cladding material with a refractive index of 1.63 was placed on the polymer waveguide. Additionally, for greater overlap, a tapered optical fiber—produced using the thermal-pulling method—was utilized. This fiber was fabricated by heating it up to 95°C and stretching it from both sides using XYZ stages. Finally, by performing edge-to-edge coupling in the laboratory and precisely positioning the fiber in front of the waveguide while adjusting the angle and directions, a loss of 11 dB was achieved. It should be noted that the intrinsic loss of the optical fiber was measured to be 7 dB. Moreover, using Lumerical simulation software, the waveguide dimensions and the refractive index of the cladding material were determined to be 1 μm and 1.63, respectively.
Fabrication and characterization of two concentric microring laser
Authors: Alireza Kavousi, Fatemeh Moradiani, Gholam-Mohammad Parsanasab
Conference: Iranian International Conference on Microelectronics, December 2022
Abstract: In this paper, we report the fabrication and characterization of two concentric microring polymer lasers. The experimental results of this laser have been compared with single microring lasers. Experimental results have illustrated that the proposed structure removes all the side modes of the single-ring laser using the Vernier effect, and only one hybrid mode is excited in the structure. To further investigate the experimental results, the numerical simulation of the microlasers has also been investigated, and the numerical results closely follow the accuracy of the experimental results. The proposed laser has excellent capabilities with integrated photonic devices because of its extremely compact dimensions and extremely low power threshold.
Fabrication and loss measurement of a polymeric Waveguides
Authors: Mohsen Mirmohammadi, Gholam Mohammad Parsanasab, Mohammad Talebi Khoshmehr
Conference: ICOP, ICPET, February 2022
Abstract: In this paper we described the importance, propagation method and some specification of optical waveguides. In the following, profits and important feature of polymeric waveguides were explained. Then, fabrication process of kind of polymeric waveguide with SU8 which is a negative photoresist and necessary setup for lithography were completely described. Finally, we describe how to couple light through optical fiber to fabricated waveguide and measuring the loss of waveguide in different wavelength and Loss value which get are 0.12, 0.9 and 0.11 dB/cm for 655 nm(visible) and 980 nm,1550 nm IR wavelength in respectively.
Investigation of outside unwanted particles diffraction on microring lasers
Authors: Pegah Aivazy Arvanagh, Fatemeh Moradiani, Mohammad Talebi Khoshmehr, and
Gholam-Mohammad Parsanasab
Conference: ICOP, ICPET, February 2022
Abstract: Here, the experimental performance of optically-pumped polymer micro-ring laser fabricated by the direct writing method of SU-8 is reported. Then the effect size of outside unwanted particles (OUP) is investigated on the sample. It has been shown when the size of OUPs are very small, the amplitude of intensity increase by 67%, and for the OUPs with bigger size, this value decrease by 55% in comparison with no OUP sample. The quality factor of samples without OUP, small, and big OUP respectively has been equal to 1212.68, 2413.32, and 1204.47.
spin-coated deposition of Chalcogenide for Lithography
Authors: Gholam mohammad parsanasab, majid taghavi, samaneh mostajeran
Conference: ICOP, ICPET, February 2020
Abstract: In this study, we first investigated the feasibility of a solution made of different types of chalcogenide powders and concluded that only amorphous chalcogenides could provide a suitable solution for spin-coated deposition. After repeating the experiments, we found that when we heat them in order to remove the solvent from the deposited films, this must be done under vacuum. Then, by direct laser writing with a continuous green laser at 100um /s at 3mw power on the films and chemically etching them, we achieved 2um optical waveguides.
Fabrication and Polarization Characterization of SU8 in Optical Integrated Circuit
Authors: Peyman Malelzadeh, Gholam Mohamad Parsanasab, Ezzedin Mohajerani
Conference: ICOP, ICPET, February 2020
Abstract: In this paper we emphasize on importance of optical integrated circuit in technology and material that used in fabrication of them . we also study the fabrication of polymeric waveguides with SU8 -2002.this material is negative photoresist which change from monomer to polymer by UV lithography and after developing and eliminate of monomers from sample surface can have any designed structures. Fiber coupling to waveguides will be introduce. In the end characterize the polarization of waveguides.
Fabrication and characterization of bottle-like microcavity laser
Authors: Mohammad Talebi Khoshmehr, Gholam-Mohammad Parsanasab, Reza Gholamzadeh, Hamidreza Ghomi
Conference: ICOP, ICPET, February 2020
Abstract: In this paper Fabrication and characterization of bottle-like microcavity laser are reported. The active medium of this laser is Rhodamine (R6G) dye solved in Su-8 solvent that put around the optical fiber like a bottle. These lasers free space pumped with second harmonic Nd: YAG pulsed laser and output spectrum of laser collected as free space. These lasers have very low pump energy density threshold that has widely used in optical sensors.