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Integrated Optics|93 Article(s)
Experimental demonstration of a performance-enhanced optical quantizer based on adjoint shape optimization
Yijun He, Jifang Qiu, Bowen Zhang, Qiuyan Li, Suping Jiao, Yan Li, and Jian Wu
We propose and demonstrate a performance-enhanced optical quantizer by inverse design. An adjoint shape co-optimization method is used to optimize the boundaries of the optical quantizer, aiming to reduce the insertion loss (IL), improve the uniformity, and increase the bandwidth of the effective number of bits (ENOB). Meanwhile, the optimized shape maintains its deep ultraviolet (DUV) photolithography fabrication capability. We fabricate the device on a commercial silicon-on-insulator (SOI) platform. Measurement results show that the IL is reduced from 0.85 to 0.35 dB, and the uniformity is optimized from 1.21 to 0.24 dB at 1550 nm. The maximum ENOB increases to 3.31 bit, which is very close to the ideal value of 3.32 bit, and the bandwidth of the ENOB > 3 bit is expanded to more than 50 nm. We propose and demonstrate a performance-enhanced optical quantizer by inverse design. An adjoint shape co-optimization method is used to optimize the boundaries of the optical quantizer, aiming to reduce the insertion loss (IL), improve the uniformity, and increase the bandwidth of the effective number of bits (ENOB). Meanwhile, the optimized shape maintains its deep ultraviolet (DUV) photolithography fabrication capability. We fabricate the device on a commercial silicon-on-insulator (SOI) platform. Measurement results show that the IL is reduced from 0.85 to 0.35 dB, and the uniformity is optimized from 1.21 to 0.24 dB at 1550 nm. The maximum ENOB increases to 3.31 bit, which is very close to the ideal value of 3.32 bit, and the bandwidth of the ENOB > 3 bit is expanded to more than 50 nm.
Chinese Optics Letters
- Publication Date: Apr. 23, 2025
- Vol. 23, Issue 4, 041301 (2025)
High-resolution waveguide array-based astronomical spectrograph with cascaded phase modulation
Yunxian Zhong, Dong Lin, Biao Xu, Zhuangzhuang Zhu, Xue Tong, Qing Zhong, Jijun Feng, and Jinping He
Integrated photonic spectrographs could provide a new generation of low-cost, highly integrated, high-performance optical terminal instruments for astronomical observations. However, these spectrographs still face the challenge of high spectral resolution. In this Letter, we demonstrate a cascaded phase-modulated waveguide array (CPMWA) spectrograph, with designed and measured spectral resolutions of 100,000 and 68,000, respectively. A spectral reconstruction method is proposed to minimize the influence of the phase error induced during the chip fabrication process and increase the spectral contrast to 20 dB. This type of spectrograph demonstrates promising potential for high-resolution spectrum observations in astronomy. Integrated photonic spectrographs could provide a new generation of low-cost, highly integrated, high-performance optical terminal instruments for astronomical observations. However, these spectrographs still face the challenge of high spectral resolution. In this Letter, we demonstrate a cascaded phase-modulated waveguide array (CPMWA) spectrograph, with designed and measured spectral resolutions of 100,000 and 68,000, respectively. A spectral reconstruction method is proposed to minimize the influence of the phase error induced during the chip fabrication process and increase the spectral contrast to 20 dB. This type of spectrograph demonstrates promising potential for high-resolution spectrum observations in astronomy.
Chinese Optics Letters
- Publication Date: Mar. 12, 2025
- Vol. 23, Issue 3, 031301 (2025)
A parameter-space-reduction-technique-assisted optimization method for characterizing recirculating waveguide meshes
Ran Tao, Jifang Qiu, Yuchen Chen, Yan Li, Hongxiang Guo, and Jian Wu
Fabrication imperfections must be considered during the configuration of programmable photonic integrated circuits (PPICs). Therefore, characterization of imperfections is crucial but challenging, especially for PPICs based on recirculating waveguide meshes. In this Letter, we propose a characterization method based on an optimization method assisted by a step-by-step parameter space reduction technique, capable of greatly broadening the range of characterized parameters compared to existing methods. Our method ensures precise characterization, enabling the modeling of defective meshes with an error of 0.35 dB. Furthermore, the method was tested under various scenarios to evaluate its stability and robustness. Finally, we applied our method to implement six different types of finite/infinite impulse response (FIR/IIR) filters to demonstrate its effective application in off-chip configuration. Fabrication imperfections must be considered during the configuration of programmable photonic integrated circuits (PPICs). Therefore, characterization of imperfections is crucial but challenging, especially for PPICs based on recirculating waveguide meshes. In this Letter, we propose a characterization method based on an optimization method assisted by a step-by-step parameter space reduction technique, capable of greatly broadening the range of characterized parameters compared to existing methods. Our method ensures precise characterization, enabling the modeling of defective meshes with an error of 0.35 dB. Furthermore, the method was tested under various scenarios to evaluate its stability and robustness. Finally, we applied our method to implement six different types of finite/infinite impulse response (FIR/IIR) filters to demonstrate its effective application in off-chip configuration.
Chinese Optics Letters
- Publication Date: Mar. 11, 2025
- Vol. 23, Issue 2, 021301 (2025)
Optical bistability in a silicon nitride microring integrated with 2D PtSe2 [Invited]
Jiaqi Wang, Yingqi Xu, Zhijian Mao, Guoxian Wu, Rongxiang Guo, Xu Li, Yu Du, Youfu Geng, Xuejin Li, Hon Ki Tsang, and Zhenzhou Cheng
Optical bistability can be used to explore key components of all-optical information processing systems, such as optical switches and optical random memories. The hybrid integration of emerged two-dimensional layered PtSe2 with waveguides is promising for the applications. We demonstrated the optical bistability in the PtSe2-on-silicon nitride microring resonator induced by a thermo-optic effect. The fabricated device has a resonance-increasing rate of 6.8 pm/mW with increasing optical power. We also established a theoretical model to explain the observation and analyze the device’s performance. The study is expected to provide a new scheme for realizing all-optical logic devices in next-generation information processing systems. Optical bistability can be used to explore key components of all-optical information processing systems, such as optical switches and optical random memories. The hybrid integration of emerged two-dimensional layered PtSe2 with waveguides is promising for the applications. We demonstrated the optical bistability in the PtSe2-on-silicon nitride microring resonator induced by a thermo-optic effect. The fabricated device has a resonance-increasing rate of 6.8 pm/mW with increasing optical power. We also established a theoretical model to explain the observation and analyze the device’s performance. The study is expected to provide a new scheme for realizing all-optical logic devices in next-generation information processing systems.
Chinese Optics Letters
- Publication Date: Sep. 03, 2024
- Vol. 22, Issue 9, 091301 (2024)
Comparative study on pump frequency tuning and self-injection locking in Kerr microcomb generation
Zhuopei Yu, Weihong Hua, Chenxi Zhang, Runlin Miao, Ke Yin, and Tian Jiang
The optical frequency comb has attracted considerable interest due to its diverse applications in optical atomic clocks, ultra-low-noise microwave generation, dual-comb spectroscopy, and optical communications. The merits of large frequency spacing, high integration, and low power consumption have shown that microresonator-based Kerr optical frequency combs will become mainstream in the future. Two methods of pump frequency tuning and self-injection locking were used to obtain Kerr combs in the same silicon nitride microresonators with free spectral ranges of 50 GHz and 100 GHz. Single-soliton combs are realized with both methods. Simplicity, pump power, spectrum bandwidth, conversion efficiency, and linewidth are compared and analyzed. Our results show that the advantages of pump frequency tuning are a wider spectrum and higher soliton power while the advantages of self-injection locking are simplicity, compactness, low cost, significant linewidth narrowing, and high conversion efficiency. The optical frequency comb has attracted considerable interest due to its diverse applications in optical atomic clocks, ultra-low-noise microwave generation, dual-comb spectroscopy, and optical communications. The merits of large frequency spacing, high integration, and low power consumption have shown that microresonator-based Kerr optical frequency combs will become mainstream in the future. Two methods of pump frequency tuning and self-injection locking were used to obtain Kerr combs in the same silicon nitride microresonators with free spectral ranges of 50 GHz and 100 GHz. Single-soliton combs are realized with both methods. Simplicity, pump power, spectrum bandwidth, conversion efficiency, and linewidth are compared and analyzed. Our results show that the advantages of pump frequency tuning are a wider spectrum and higher soliton power while the advantages of self-injection locking are simplicity, compactness, low cost, significant linewidth narrowing, and high conversion efficiency.
Chinese Optics Letters
- Publication Date: Aug. 21, 2024
- Vol. 22, Issue 8, 081301 (2024)
Independent dual beams generated by array element division in integrated optical phased arrays|Editors' Pick
Guihan Wu, Yu Xin, Lemeng Leng, Xiang Ji, Shichong Yang, Kaifei Tang, Quan Luo, Hongsheng Luo, Jinshan Su, and Wei Jiang
Optical phased arrays (OPAs) have broad application prospects due to their advanced capability in beamforming and steering. In this work, we achieve independent dual beams in the far field by dividing the array elements of the OPA, with the maximum scanning range reaching 100°. Based on the working principle of OPAs, theoretical considerations of such multi-beam generation are presented. A phase data allocation approach for OPAs in the presence of fabrication-induced random phase variation is developed. Simulations of large ensembles of OPAs with various levels of random residual phase errors have been conducted to help analyze the results. This approach can help OPAs realize multi-beams for light detection and ranging (LiDAR). Optical phased arrays (OPAs) have broad application prospects due to their advanced capability in beamforming and steering. In this work, we achieve independent dual beams in the far field by dividing the array elements of the OPA, with the maximum scanning range reaching 100°. Based on the working principle of OPAs, theoretical considerations of such multi-beam generation are presented. A phase data allocation approach for OPAs in the presence of fabrication-induced random phase variation is developed. Simulations of large ensembles of OPAs with various levels of random residual phase errors have been conducted to help analyze the results. This approach can help OPAs realize multi-beams for light detection and ranging (LiDAR).
Chinese Optics Letters
- Publication Date: Jul. 30, 2024
- Vol. 22, Issue 7, 071301 (2024)
Passively stable 0.7-octave microcombs in thin-film lithium niobate microresonators|Editors' Pick
Zexing Zhao, Chenyu Wang, Jingyuan Qiu, Zhilin Ye, Zhijun Yin, Zhenlin Wang, Kunpeng Jia, Xiao-Hui Tian, Zhenda Xie, and Shi-Ning Zhu
The optical frequency comb based on microresonators (microcombs) is an integrated coherent light source and has the potential to promise a high-precision frequency standard; self-reference and a long-term stable microcomb are the keys to this realization. Here, we demonstrated a 0.7-octave spectrum Kerr comb via dispersion engineering in a thin-film lithium niobate microresonator, and the single-soliton state can be accessed passively with long-term stability over 3 h. With such a robust broadband coherent comb source using thin-film lithium niobate, a fully stabilized microcomb can be expected for massive practical applications. The optical frequency comb based on microresonators (microcombs) is an integrated coherent light source and has the potential to promise a high-precision frequency standard; self-reference and a long-term stable microcomb are the keys to this realization. Here, we demonstrated a 0.7-octave spectrum Kerr comb via dispersion engineering in a thin-film lithium niobate microresonator, and the single-soliton state can be accessed passively with long-term stability over 3 h. With such a robust broadband coherent comb source using thin-film lithium niobate, a fully stabilized microcomb can be expected for massive practical applications.
Chinese Optics Letters
- Publication Date: May. 14, 2024
- Vol. 22, Issue 5, 051301 (2024)
Erbium-ytterbium co-doped lithium niobate single-mode microdisk laser with an ultralow threshold of 1 µW
Minghui Li, Renhong Gao, Chuntao Li, Jianglin Guan, Haisu Zhang, Jintian Lin, Guanghui Zhao, Qian Qiao, Min Wang, Lingling Qiao, Li Deng, and Ya Cheng
We demonstrate single-mode microdisk lasers in the telecom band with ultralow thresholds on erbium-ytterbium co-doped thin-film lithium niobate (TFLN). The active microdisk was fabricated with high-Q factors by photolithography-assisted chemomechanical etching. Thanks to the erbium-ytterbium co-doping providing high optical gain, the ultralow loss nanostructuring, and the excitation of high-Q coherent polygon modes, which suppresses multimode lasing and allows high spatial mode overlap between pump and lasing modes, single-mode laser emission operating at 1530 nm wavelength was observed with an ultralow threshold, under a 980-nm-band optical pump. The threshold was measured as low as 1 µW, which is one order of magnitude smaller than the best results previously reported in single-mode active TFLN microlasers. The conversion efficiency reaches 4.06 × 10-3, which is also the highest value reported in single-mode active TFLN microlasers. We demonstrate single-mode microdisk lasers in the telecom band with ultralow thresholds on erbium-ytterbium co-doped thin-film lithium niobate (TFLN). The active microdisk was fabricated with high-Q factors by photolithography-assisted chemomechanical etching. Thanks to the erbium-ytterbium co-doping providing high optical gain, the ultralow loss nanostructuring, and the excitation of high-Q coherent polygon modes, which suppresses multimode lasing and allows high spatial mode overlap between pump and lasing modes, single-mode laser emission operating at 1530 nm wavelength was observed with an ultralow threshold, under a 980-nm-band optical pump. The threshold was measured as low as 1 µW, which is one order of magnitude smaller than the best results previously reported in single-mode active TFLN microlasers. The conversion efficiency reaches 4.06 × 10-3, which is also the highest value reported in single-mode active TFLN microlasers.
Chinese Optics Letters
- Publication Date: Apr. 17, 2024
- Vol. 22, Issue 4, 041301 (2024)
Microwave photonic sideband selector based on thin-film lithium niobate platform
Yuedi Ding, Chenglin Shang, Wenqi Yu, Xiang Ma, Shaobo Li, Cheng Zeng, and Jinsong Xia
We propose and demonstrate an integrated microwave photonic sideband selector based on the thin-film lithium niobate (TFLN) platform by integrating an electro-optic Mach–Zehnder modulator (MZM) and a thermo-optic tunable flat-top microring filter. The sideband selector has two functions: electro-optic modulation of wideband RF signal and sideband selection. The microwave photonic sideband selector supports processing RF signals up to 40 GHz, with undesired sidebands effectively suppressed by more than 25 dB. The demonstrated device shows great potential for TFLN integrated technology in microwave photonic applications, such as mixing and frequency measurement. We propose and demonstrate an integrated microwave photonic sideband selector based on the thin-film lithium niobate (TFLN) platform by integrating an electro-optic Mach–Zehnder modulator (MZM) and a thermo-optic tunable flat-top microring filter. The sideband selector has two functions: electro-optic modulation of wideband RF signal and sideband selection. The microwave photonic sideband selector supports processing RF signals up to 40 GHz, with undesired sidebands effectively suppressed by more than 25 dB. The demonstrated device shows great potential for TFLN integrated technology in microwave photonic applications, such as mixing and frequency measurement.
Chinese Optics Letters
- Publication Date: Mar. 25, 2024
- Vol. 22, Issue 3, 031304 (2024)
Ultralow cross talk arrayed waveguide grating integrated with tunable microring filter array|On the Cover
Heming Hu, Shiping Liu, Tianwen Li, Yongjie Fan, Hua Chen, and Qing Fang
The silicon-based arrayed waveguide grating (AWG) is widely used due to its compact footprint and its compatibility with the mature CMOS process. However, except for AWGs with ridged waveguides of a few micrometers of cross section, any small process error will cause a large phase deviation in other AWGs, resulting in an increasing cross talk. In this paper, an ultralow cross talk AWG via a tunable microring resonator (MRR) filter is demonstrated on the SOI platform. The measured insertion loss and minimum adjacent cross talk of the designed AWG are approximately 3.2 and -45.1 dB, respectively. Compared with conventional AWG, its cross talk is greatly reduced. The silicon-based arrayed waveguide grating (AWG) is widely used due to its compact footprint and its compatibility with the mature CMOS process. However, except for AWGs with ridged waveguides of a few micrometers of cross section, any small process error will cause a large phase deviation in other AWGs, resulting in an increasing cross talk. In this paper, an ultralow cross talk AWG via a tunable microring resonator (MRR) filter is demonstrated on the SOI platform. The measured insertion loss and minimum adjacent cross talk of the designed AWG are approximately 3.2 and -45.1 dB, respectively. Compared with conventional AWG, its cross talk is greatly reduced.
Chinese Optics Letters
- Publication Date: Mar. 07, 2024
- Vol. 22, Issue 3, 031303 (2024)
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