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Integrated Optics|80 Article(s)
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)
Research progress of integrated optical gyroscope
Hongjie Guo, Haifeng Liu, Ming Lei, Manqing Tan, and Zhigang Song
Integrated optical gyroscopes (IOGs) have been an efficient tool for numerous applications in various fields, including inertial navigation, flight control, and earthquake monitoring. Here, we review the progress of integrated optical gyroscopes based on two categories of integrated interferometric optical gyroscopes (IIOGs) and integrated resonant optical gyroscopes (IROGs). Integrated optical gyroscopes (IOGs) have been an efficient tool for numerous applications in various fields, including inertial navigation, flight control, and earthquake monitoring. Here, we review the progress of integrated optical gyroscopes based on two categories of integrated interferometric optical gyroscopes (IIOGs) and integrated resonant optical gyroscopes (IROGs).
Chinese Optics Letters
- Publication Date: Mar. 15, 2024
- Vol. 22, Issue 3, 031302 (2024)
Ultra-compact and broadband polarization-insensitive mode-order converting power splitter
Haoqi Chen, Runkui Yao, Pengjun Wang, Qiang Fu, Weiwei Chen, Shixun Dai, Dejun Kong, Jian Lin, Tao Jin, Jun Li, Tingge Dai, and Jianyi Yang
A polarization-insensitive mode-order converting power splitter using a pixelated region is presented and investigated in this paper. As TE0 and TM0 modes are injected into the input port, they are converted into TE1 and TM1 modes, which evenly come out from the two output ports. The finite-difference time-domain method and direct-binary-search optimization algorithm are utilized to optimize structural parameters of the pixelated region to attain small insertion loss, low crosstalk, wide bandwidth, excellent power uniformity, polarization-insensitive property, and compact size. Experimental results reveal that the insertion loss, crosstalk, and power uniformity of the fabricated device at 1550 nm are 0.57, -19.67, and 0.094 dB in the case of TE polarization, while in the TM polarization, the relevant insertion loss, crosstalk, and power uniformity are 0.57, -19.40, and 0.11 dB. Within a wavelength range from 1520 to 1600 nm, for the fabricated device working at TE polarization, the insertion loss, crosstalk, and power uniformity are lower than 1.39, -17.64, and 0.14 dB. In the case of TM polarization, we achieved an insertion loss, crosstalk, and power uniformity less than 1.23, -17.62, and 0.14 dB. A polarization-insensitive mode-order converting power splitter using a pixelated region is presented and investigated in this paper. As TE0 and TM0 modes are injected into the input port, they are converted into TE1 and TM1 modes, which evenly come out from the two output ports. The finite-difference time-domain method and direct-binary-search optimization algorithm are utilized to optimize structural parameters of the pixelated region to attain small insertion loss, low crosstalk, wide bandwidth, excellent power uniformity, polarization-insensitive property, and compact size. Experimental results reveal that the insertion loss, crosstalk, and power uniformity of the fabricated device at 1550 nm are 0.57, -19.67, and 0.094 dB in the case of TE polarization, while in the TM polarization, the relevant insertion loss, crosstalk, and power uniformity are 0.57, -19.40, and 0.11 dB. Within a wavelength range from 1520 to 1600 nm, for the fabricated device working at TE polarization, the insertion loss, crosstalk, and power uniformity are lower than 1.39, -17.64, and 0.14 dB. In the case of TM polarization, we achieved an insertion loss, crosstalk, and power uniformity less than 1.23, -17.62, and 0.14 dB.
Chinese Optics Letters
- Publication Date: Mar. 19, 2024
- Vol. 22, Issue 3, 031301 (2024)
O-band reconfigurable silicon polarization rotator
Yawen Bai, Pengfei Wang, Bo Peng, and Tao Chu
Silicon waveguides typically exhibit optical anisotropy, which leads to polarization correlation and single-polarization operations. This consequently creates a demand for polarization-control devices. This paper introduces a CMOS-compatible O-band reconfigurable TE/TM polarization rotator comprising two symmetrical polarization rotator–splitters and phase shifters. This configuration enables dynamic conversion of any linear polarization to its quadratic equivalent. Experimental results indicate that the reconfigurable polarization rotator exhibits an insertion loss of less than 1.5 dB. Furthermore, the bandwidth for a polarization extinction ratio beyond 15 dB exceeds 60 nm. Silicon waveguides typically exhibit optical anisotropy, which leads to polarization correlation and single-polarization operations. This consequently creates a demand for polarization-control devices. This paper introduces a CMOS-compatible O-band reconfigurable TE/TM polarization rotator comprising two symmetrical polarization rotator–splitters and phase shifters. This configuration enables dynamic conversion of any linear polarization to its quadratic equivalent. Experimental results indicate that the reconfigurable polarization rotator exhibits an insertion loss of less than 1.5 dB. Furthermore, the bandwidth for a polarization extinction ratio beyond 15 dB exceeds 60 nm.
Chinese Optics Letters
- Publication Date: Jan. 19, 2024
- Vol. 22, Issue 1, 011303 (2024)
Inverse design of highly efficient and broadband mode splitter on SOI platform
Junpeng Liao, Ye Tian, Zirong Yang, Haoda Xu, Chen Tang, Yuheng Wang, Xiaowei Zhang, and Zhe Kang
Mode splitters that directly separate modes without changing their orders are highly promising to improve the flexibility of the mode-division multiplexing systems. In this paper, we design a high-performance mode splitter on the silicon-on-insulator platform with a compact footprint of 14 µm× 2.5 µm using an inverse design method based on shape optimization. The fabrication of this mode splitter requires only a single lithography step and exhibits good fabrication tolerances. The experimental results show that the proposed device exhibits state-of-the-art insertion loss (<0.9 dB) and cross talk (<-16 dB) over a broad bandwidth (1500–1600 nm). Furthermore, the shape optimization method used is implemented to design a dual-mode (de)multiplexer, and the experimental results fulfill the design objective, demonstrating the excellent generality of the design method in this paper. Mode splitters that directly separate modes without changing their orders are highly promising to improve the flexibility of the mode-division multiplexing systems. In this paper, we design a high-performance mode splitter on the silicon-on-insulator platform with a compact footprint of 14 µm× 2.5 µm using an inverse design method based on shape optimization. The fabrication of this mode splitter requires only a single lithography step and exhibits good fabrication tolerances. The experimental results show that the proposed device exhibits state-of-the-art insertion loss (<0.9 dB) and cross talk (<-16 dB) over a broad bandwidth (1500–1600 nm). Furthermore, the shape optimization method used is implemented to design a dual-mode (de)multiplexer, and the experimental results fulfill the design objective, demonstrating the excellent generality of the design method in this paper.
Chinese Optics Letters
- Publication Date: Jan. 22, 2024
- Vol. 22, Issue 1, 011302 (2024)
Experimental demonstration of a flexible-grid 1 × (2 × 3) mode- and wavelength-selective switch using silicon microring resonators and counter-tapered couplers
Dejun Kong, Hao Lu, Pengjun Wang, Qiang Fu, Shixun Dai, Weiwei Chen, Yuefeng Wang, Bohao Zhang, Lingxiao Ma, Jun Li, Tingge Dai, and Jianyi Yang
A flexible-grid 1×(2×3) mode- and wavelength-selective switch which comprises counter-tapered couplers and silicon microring resonators has been proposed, optimized, and demonstrated experimentally in this work. By carefully thermally tuning phase shifters and silicon microring resonators, mode and wavelength signals can be independently and flexibly conveyed to any one of the output ports, and different bandwidths can be generated as desired. The particle swarm optimization algorithm and finite difference time-domain method are employed to optimize structural parameters of the two-mode (de)multiplexer and crossing waveguide. The bandwidth-tunable wavelength-selective optical router composed of 12 microring resonators is studied by taking advantage of the transfer matrix method. Measurement results show that, for the fabricated module, cross talk less than -10.18 dB, an extinction ratio larger than 17.41 dB, an in-band ripple lower than 0.79 dB, and a 3-dB bandwidth changing from 0.38 to 1.05 nm are obtained, as the wavelength-channel spacing is 0.40 nm. The corresponding response time is measured to be 13.64 µs. A flexible-grid 1×(2×3) mode- and wavelength-selective switch which comprises counter-tapered couplers and silicon microring resonators has been proposed, optimized, and demonstrated experimentally in this work. By carefully thermally tuning phase shifters and silicon microring resonators, mode and wavelength signals can be independently and flexibly conveyed to any one of the output ports, and different bandwidths can be generated as desired. The particle swarm optimization algorithm and finite difference time-domain method are employed to optimize structural parameters of the two-mode (de)multiplexer and crossing waveguide. The bandwidth-tunable wavelength-selective optical router composed of 12 microring resonators is studied by taking advantage of the transfer matrix method. Measurement results show that, for the fabricated module, cross talk less than -10.18 dB, an extinction ratio larger than 17.41 dB, an in-band ripple lower than 0.79 dB, and a 3-dB bandwidth changing from 0.38 to 1.05 nm are obtained, as the wavelength-channel spacing is 0.40 nm. The corresponding response time is measured to be 13.64 µs.
Chinese Optics Letters
- Publication Date: Jan. 02, 2024
- Vol. 22, Issue 1, 011301 (2024)
Integrated diffractive optical neural network with space-time interleaving
Tingzhao Fu, Yuyao Huang, Run Sun, Honghao Huang, Wencan Liu, Sigang Yang, and Hongwei Chen
Integrated diffractive optical neural networks (DONNs) have significant potential for complex machine learning tasks with high speed and ultralow energy consumption. However, the on-chip implementation of a high-performance optical neural network is limited by input dimensions. In contrast to existing photonic neural networks, a space-time interleaving technology based on arrayed waveguides is designed to realize an on-chip DONN with high-speed, high-dimensional, and all-optical input signal modulation. To demonstrate the performance of the on-chip DONN with high-speed space-time interleaving modulation, an on-chip DONN with a designed footprint of 0.0945 mm2 is proposed to resolve the vowel recognition task, reaching a computation speed of about 1.4×1013 operations per second and yielding an accuracy of 98.3% in numerical calculation. In addition, the function of the specially designed arrayed waveguides for realizing parallel signal inputs using space-time conversion has been verified experimentally. This method can realize the on-chip DONN with higher input dimension and lower energy consumption. Integrated diffractive optical neural networks (DONNs) have significant potential for complex machine learning tasks with high speed and ultralow energy consumption. However, the on-chip implementation of a high-performance optical neural network is limited by input dimensions. In contrast to existing photonic neural networks, a space-time interleaving technology based on arrayed waveguides is designed to realize an on-chip DONN with high-speed, high-dimensional, and all-optical input signal modulation. To demonstrate the performance of the on-chip DONN with high-speed space-time interleaving modulation, an on-chip DONN with a designed footprint of 0.0945 mm2 is proposed to resolve the vowel recognition task, reaching a computation speed of about 1.4×1013 operations per second and yielding an accuracy of 98.3% in numerical calculation. In addition, the function of the specially designed arrayed waveguides for realizing parallel signal inputs using space-time conversion has been verified experimentally. This method can realize the on-chip DONN with higher input dimension and lower energy consumption.
Chinese Optics Letters
- Publication Date: Aug. 22, 2023
- Vol. 21, Issue 9, 091301 (2023)
Cryogenic thermo-optic thin-film lithium niobate modulator with an NbN superconducting heater
Hailong Han, Xingyu Zhang, You Xiao, Pusheng Yuan, Huiqin Yu, Shuna Wang, Heng Li, Weikeng Xie, Mingzhi Lu, Lingyun Li, Xiaoping Liu, Hao Li, and Lixing You
We propose and demonstrate a cryogenic thermo-optic (TO) modulator in x-cut thin-film lithium niobate (TFLN) with an NbN superconducting heater. Compared to a conventional metal heating electrode, a fast and energy-efficient modulation is obtained by placing an NbN superconducting heating electrode above the TFLN waveguide. The transition of the NbN superconducting electrode between superconducting and normal states turns the heating and cooling processes from continuous to discontinuous change. Thus, the energy consumption during the modulation process is reduced proportionally. The rise/fall time of the proposed device is 22 µs/15 µs, which has been the fastest response time reported in TFLN thermo-optic modulators so far. The presented TO modulator can easily be used at cryogenic temperatures and has great potential for applications in cryogenic optoelectronics. We propose and demonstrate a cryogenic thermo-optic (TO) modulator in x-cut thin-film lithium niobate (TFLN) with an NbN superconducting heater. Compared to a conventional metal heating electrode, a fast and energy-efficient modulation is obtained by placing an NbN superconducting heating electrode above the TFLN waveguide. The transition of the NbN superconducting electrode between superconducting and normal states turns the heating and cooling processes from continuous to discontinuous change. Thus, the energy consumption during the modulation process is reduced proportionally. The rise/fall time of the proposed device is 22 µs/15 µs, which has been the fastest response time reported in TFLN thermo-optic modulators so far. The presented TO modulator can easily be used at cryogenic temperatures and has great potential for applications in cryogenic optoelectronics.
Chinese Optics Letters
- Publication Date: Aug. 08, 2023
- Vol. 21, Issue 8, 081301 (2023)
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