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12 pages, 8149 KiB

Open AccessCommunication

Process Development of Low-Loss LPCVD Silicon Nitride Waveguides on 8-Inch Wafer

by Zhaoyi Li, Zuowen Fan, Jingjie Zhou, Qingyu Cong, Xianfeng Zeng, Yumei Zhang and Lianxi Jia

Appl. Sci. 2023, 13(6), 3660; https://doi.org/10.3390/app13063660 - 13 Mar 2023

Cited by 13 | Viewed by 7190

Abstract

Silicon nitride is a material compatible with CMOS processes and offers several advantages, such as a wide transparent window, a large forbidden band gap, negligible two-photon absorption, excellent nonlinear properties, and a smaller thermo-optic coefficient than silicon. Therefore, it has received significant attention [...] Read more.

Silicon nitride is a material compatible with CMOS processes and offers several advantages, such as a wide transparent window, a large forbidden band gap, negligible two-photon absorption, excellent nonlinear properties, and a smaller thermo-optic coefficient than silicon. Therefore, it has received significant attention in the field of silicon photonics in recent years. The preparation of silicon nitride waveguides using low-pressure chemical vapor deposition methods results in lower loss and better process repeatability. However, due to the higher temperature of the process, when the thickness of the silicon nitride film exceeds 300 nm on an 8-inch wafer, it is prone to cracking due to the high stress generated by the film. Limited by this high stress, silicon nitride waveguide devices are typically developed on wafers with a thickness of 4 inches or less. In this work, we successfully fabricated a 400 nm-thick silicon nitride waveguide on an 8-inch wafer using a Damascene method similar to the CMOS process for copper interconnects and demonstrated propagation losses of only 0.157 dB/cm at 1550 nm and 0.06 dB/cm at 1580 nm. Full article

(This article belongs to the Special Issue Laser and Silicon Photonics: Technology, Preparation and Application)

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8 pages, 2026 KiB

Open AccessCommunication

16-Channel Wavelength Division Multiplexers Based on Subwavelength Grating

by Yawen Bai, Lin Wang, Lei Zhang, Pengfei Wang and Bo Peng

Appl. Sci. 2023, 13(3), 1833; https://doi.org/10.3390/app13031833 - 31 Jan 2023

Cited by 3 | Viewed by 2072

Abstract

Wavelength Division Multiplexing (WDM) plays an important role in optical interconnection. In this paper, a 16-channel WDM device is designed on a Silicon-On-Insulator (SOI) substrate by using a sub-wavelength grating (SWG) structure, which can cover O-band and C-band at the same time, and [...] Read more.

Wavelength Division Multiplexing (WDM) plays an important role in optical interconnection. In this paper, a 16-channel WDM device is designed on a Silicon-On-Insulator (SOI) substrate by using a sub-wavelength grating (SWG) structure, which can cover O-band and C-band at the same time, and the output channel is reversely coupled from the main waveguide to realize wavelength demultiplexing. The simulation results show that the loss of our 16-channel wavelength demultiplexing device is less than 0.5 dB and the crosstalk is less than 17 dB. When WDM is performed in O-band, the transmission loss of the C-band in the bus waveguide is less than 0.05 dB and is insensitive to the grating duty cycle, with good process tolerance. The footprint of the device is 200 μm × 150 μm, and the size of the single-channel filter is 200 μm × 2 μm, which can realize WDM with large bandwidth in a compact structure. Full article

(This article belongs to the Special Issue Laser and Silicon Photonics: Technology, Preparation and Application)

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9 pages, 4284 KiB

Open AccessCommunication

Wideband E₀₀-E₁₀ Silicon Mode Converter Based on 180 nm CMOS Technology

by Yan Xu, Yang Gao, Songyue Liu, Tingyu Liu, Xiaoqiang Sun, Bo Tang, Peng Zhang and Daming Zhang

Appl. Sci. 2022, 12(20), 10688; https://doi.org/10.3390/app122010688 - 21 Oct 2022

Cited by 2 | Viewed by 1663

Abstract

Mode division multiplexing (MDM) is a promising technology for the capacity enlargement of the optical transmission network. As a key element in the MDM system, the mode converter plays an important role in signal processing. In this work, a wideband E₀₀-E [...] Read more.

Mode division multiplexing (MDM) is a promising technology for the capacity enlargement of the optical transmission network. As a key element in the MDM system, the mode converter plays an important role in signal processing. In this work, a wideband E₀₀-E₁₀ silicon mode converter constructed by Y-branch and cascaded multimode interference coupler is demonstrated. The theoretical mode crosstalk is less than –29.2 dB within the wavelength range from 1540 nm to 1600 nm. By 180 nm standard CMOS fabrication, the tested mode conversion efficiency of 91.5% and the crosstalk of −10.3 dB can be obtained at 1575.9 nm. The 3 dB bandwidth is over 60 nm. The proposed E₀₀-E₁₀ silicon mode converter is applicable in mode multiplexing. Full article

(This article belongs to the Special Issue Laser and Silicon Photonics: Technology, Preparation and Application)

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11 pages, 2222 KiB

Open AccessArticle

Ultra-Compact Digital Metasurface Polarization Beam Splitter via Physics-Constrained Inverse Design

by Hao Shi, Lin Wang, Lei Zhang, Yanqing Wu, Zhenjiang Li, Lu Wang and Renzhong Tai

Appl. Sci. 2022, 12(19), 10064; https://doi.org/10.3390/app121910064 - 7 Oct 2022

Cited by 4 | Viewed by 2096

Abstract

Inverse design effectively promotes the miniaturization of integrated photonic devices through the modulation of subwavelength structures. Utilizing a theoretical prior based inverse design, we propose an ultra-compact integrated polarizing beam splitter consisting of a standard silicon-on-insulator (SOI) substrate and a tunable air–silicon column [...] Read more.

Inverse design effectively promotes the miniaturization of integrated photonic devices through the modulation of subwavelength structures. Utilizing a theoretical prior based inverse design, we propose an ultra-compact integrated polarizing beam splitter consisting of a standard silicon-on-insulator (SOI) substrate and a tunable air–silicon column two-dimensional code metasurface, with a footprint of 5 × 2.7 μm². The effective refractive index of the waveguide is modulated by adjusting the two-dimensional code morphology in the additional layer to achieve efficient polarization beam splitting. The simulation results demonstrate high performance, with a low insertion loss (<0.87 dB) and high extinction ratio (>10.76 dB) in a bandwidth of 80 nm covering the C-band. The device can withstand manufacturing errors up to ±20 nm and is robust to process defects, such as the outer proximity effect, and thus is suitable for ultra-compact on-chip optical interconnects. Full article

(This article belongs to the Special Issue Laser and Silicon Photonics: Technology, Preparation and Application)

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9 pages, 2764 KiB

Open AccessArticle

Improved SPGD Algorithm for Optical Phased Array Phase Calibration

by Zheng Wang, Yibo Yang, Ruiting Wang, Guangzhen Luo, Pengfei Wang, Yanmei Su, Jiaoqing Pan and Yejin Zhang

Appl. Sci. 2022, 12(15), 7879; https://doi.org/10.3390/app12157879 - 5 Aug 2022

Cited by 6 | Viewed by 2220

Abstract

A chip-level optical beam steerer is an inevitable choice for next-generation light detection and ranging (LiDAR). The research on optical phased array (OPA) is the most intriguing. However, the complexity of control and calibration speed limit the full potential as the number of [...] Read more.

A chip-level optical beam steerer is an inevitable choice for next-generation light detection and ranging (LiDAR). The research on optical phased array (OPA) is the most intriguing. However, the complexity of control and calibration speed limit the full potential as the number of channels increases. In this paper, an improved stochastic parallel gradient-descent algorithm combined with the Nesterov accelerated gradient method (NSPGD) is presented and applied in a 512-channel OPA. This algorithm can reduce the phase calibration time of large-scale OPA and demonstrates a better convergence performance than traditional SPGD. Compared with the traditional SPGD and hill-climbing (HC) algorithm, optimized convergence performance of NSPGD is shown. The side mode suppression ratio (SMSR) of over 10dB for 512-channel OPA is obtained with the NSPGD algorithm, and the convergence speed is twice that of traditional SPGD. In addition, a temperature-controlled OPA is also studied to stabilize the whole calibration system. Full article

(This article belongs to the Special Issue Laser and Silicon Photonics: Technology, Preparation and Application)

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11 pages, 5136 KiB

Open AccessArticle

Numerical Analysis of a Dual-Wavelength-Clad-Pumped 3.5 μm Erbium-Doped Fluoride Fiber Laser

by Kaidi Cai, Xin Zhang, Lijie Wang, Yanjing Wang, Huanyu Lu, Cunzhu Tong and Lijun Wang

Appl. Sci. 2022, 12(15), 7666; https://doi.org/10.3390/app12157666 - 29 Jul 2022

Cited by 3 | Viewed by 1520

Abstract

The stability and efficiency of a 3.5 μm erbium-doped fluoride fiber is strongly limited by the core pumping setup of a 1976 nm pump. A dual-wavelength-clad-pumped scheme was put forward for a more robust and higher electro-optical efficiency in this paper, and a [...] Read more.

The stability and efficiency of a 3.5 μm erbium-doped fluoride fiber is strongly limited by the core pumping setup of a 1976 nm pump. A dual-wavelength-clad-pumped scheme was put forward for a more robust and higher electro-optical efficiency in this paper, and a numerical model was built up to stimulate the fiber. Parameter optimizations were given for both the traditional dual-wavelength pump setup and our new scheme. The results show the possibility of using a laser diode as pump source for the generation of a 3.5 μm laser, and the characteristics were analyzed. Full article

(This article belongs to the Special Issue Laser and Silicon Photonics: Technology, Preparation and Application)

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Review

Jump to: Research

44 pages, 8733 KiB

Open AccessReview

Optical Waveguide Refractive Index Sensor for Biochemical Sensing

by Cheng Peng, Changjin Yang, Huan Zhao, Lei Liang, Chuantao Zheng, Chen Chen, Li Qin and Hui Tang

Appl. Sci. 2023, 13(6), 3829; https://doi.org/10.3390/app13063829 - 16 Mar 2023

Cited by 27 | Viewed by 6316

Abstract

This study describes the basic principles of optical waveguide refractive index sensing and the various design structures of refractive index sensors. These waveguides generate different optical resonances, which cause changes in the sensing refractive index and temperature and are subsequently used to detect [...] Read more.

This study describes the basic principles of optical waveguide refractive index sensing and the various design structures of refractive index sensors. These waveguides generate different optical resonances, which cause changes in the sensing refractive index and temperature and are subsequently used to detect the concentration in the analyses. First, the structural characteristics and performance indices of the microring sensor and interferometer are studied based on the refractive index of the optical waveguide. Second, the principle and sensing detection mechanism of the two types of refractive index sensing employed in these sensors are analyzed. Then, the two sensors are classified and discussed from the perspective of the waveguide materials and structures, as well as the substances to be measured. Simultaneously, performance indicators such as sensitivity and detection range are compared and summarized. The comparison results show that there is a compromise between the sensitivity and quality factor of the optical waveguide refractive index sensor. Finally, applications of refractive index sensing in the biochemical field for material detection are discussed, showing that the optical waveguide refractive index sensor has significant advantages over other types of biochemical optical sensors. Full article

(This article belongs to the Special Issue Laser and Silicon Photonics: Technology, Preparation and Application)

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14 pages, 2316 KiB

Open AccessReview

Recent Progress in On-Chip Erbium-Based Light Sources

by Bo Wang, Peiqi Zhou and Xingjun Wang

Appl. Sci. 2022, 12(22), 11712; https://doi.org/10.3390/app122211712 - 18 Nov 2022

Cited by 5 | Viewed by 2283

Abstract

In recent years, silicon photonics has achieved great success in optical communication area. More and more on-chip optoelectronic devices have been realized and commercialized on silicon photonics platform, such as silicon-based modulators, filters and detectors. However, on-chip light sources are still not achieved [...] Read more.

In recent years, silicon photonics has achieved great success in optical communication area. More and more on-chip optoelectronic devices have been realized and commercialized on silicon photonics platform, such as silicon-based modulators, filters and detectors. However, on-chip light sources are still not achieved because that silicon is an indirect bandgap material. To solve this problem, the rare earth element erbium (Er) is considered, which emits light covering 1.5 μm to 1.6 μm and has been widely used in fiber amplifiers. Compared to Er-doped fiber amplifiers (EDFA), the Er ion concentration needs to be more than two orders higher for on-chip Er-based light sources due to the compact size integration requirements. Therefore, the choice of the host material is crucially important. In this paper, we review the recent progress in on-chip Er-based light sources and the advantages and disadvantages of different host materials are compared and analyzed. Finally, the existing challenges and development directions of the on-chip Er-based light sources are discussed. Full article

(This article belongs to the Special Issue Laser and Silicon Photonics: Technology, Preparation and Application)

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