Contents
2021
Volume: 19 Issue 9
19 Article(s)

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Research Articles
Instrumentation, Measurement, and Optical Sensing
High sensitivity cascaded helical-core fiber SPR sensors
Xianbin Wang, Hongchang Deng, and Libo Yuan
The distributed optical fiber surface plasmon resonance (SPR) sensors have attracted wide attention in biosensing and chemical sensing applications. However, due to the limitation of their sensing structure, it is difficult to adjust their resonant wavelength and sensitivity. Here, novel and flexible cascaded helical-core fiber (HCF) SPR sensors are proposed theoretically and experimentally for distributed sensing applications. It is shown that the resonant wavelength and sensitivity of the sensors can be conveniently controlled by adjusting the twist pitch of the helical core. A high sensitivity of 11,180 nm/RIU for refractive-index measurement ranging from 1.355 to 1.365 is realized experimentally when the twist pitch of the helical core is 1.5 mm. It is worth noting that the sensitivity can be further improved by reducing the twist pitch. For example, the sensitivity of the sensor with a twist pitch of 1.4 mm can theoretically exceed 20,000 nm/RIU. This work opens up a new way to implement multi-parameter or distributed measurement, especially to establish sensing networks integrated in a single-core fiber or a multi-core fiber.
Chinese Optics Letters
  • Publication Date: Jul. 08, 2021
  • Vol.19 Issue, 9 091201 (2021)
Random Bragg-grating-based wavelength-tunable random fiber laser with a full-open cavity
Bing Lü, Wentao Zhang, Wenzhu Huang, and Fang Li
Chinese Optics Letters
  • Publication Date: Jun. 15, 2021
  • Vol.19 Issue, 9 091203 (2021)
Lasers, Optical Amplifiers, and Laser Optics
Stable noise-like pulse generation in all-PM mode-locked Tm-doped fiber laser based on NOLM
Meng Wang, Minqiu Liu, Yewang Chen, Deqin Ouyang, Junqing Zhao, Jihong Pei, and Shuangchen Ruan
Chinese Optics Letters
  • Publication Date: Jun. 21, 2021
  • Vol.19 Issue, 9 091402 (2021)
Theoretical analysis of periodically poled LiNbO3 nonlinear mirror and its application in a passively mode-locked Nd:YSAG laser
Lina Zhao, Fangxin Cai, Luyang Tong, Ye Yuan, Wenyu Zhang, and Yangjian Cai
Chinese Optics Letters
  • Publication Date: Jun. 15, 2021
  • Vol.19 Issue, 9 091403 (2021)
Enhanced optical absorption surface of titanium fabricated by a femtosecond laser assisted with airflow pressure
Xun Li, Ming Li, and Hongjun Liu
We propose an effective way to achieve an enhanced optical absorption surface of titanium alloy 7 (Ti7) fabricated by a femtosecond (fs) laser assisted with airflow pressure. The effect of laser scanning speed and laser power on the surfaces’ morphology and average reflectivity was studied. In order to further reduce the surface’s reflectivity, different airflow pressure was introduced during the fabrication of Ti7 by a fs laser. Furthermore, the average reflectivity of samples fabricated under different laser parameters assisted with airflow was presented. In addition, the high and low temperature tests of all samples were performed to test the stability performance of the hybrid micro/nanostructures in extreme environments. It is demonstrated that the airflow pressure has an important influence on the micro/nanostructures for light trapping, the average reflectivity of which could be as low as 2.31% over a broad band of 250–2300 nm before high and low temperature tests, and the reflection for specific wavelengths can go below 1.5%.
Chinese Optics Letters
  • Publication Date: Jun. 15, 2021
  • Vol.19 Issue, 9 091404 (2021)
GSA and ESA dual-wavelength pumped 2.3 μm Tm:YLF laser on the 3H43H5 transition
Fei Wang, Haitao Huang, Haiwei Chen, Yushuo Bao, Zihan Li, and Deyuan Shen
The population trapping effect of the F34 level is an important factor limiting the power scaling of the 2.3 μm thulium (Tm) laser on the H34→H35 transition. In this Letter, we demonstrate a novel scheme of ground state absorption (GSA) (H36→H34) and excited state absorption (ESA) (F34→H34) dual-wavelength pumped 2.3 μm Tm lasers. Introducing an ESA pumping process can accurately excite the Tm3+ ions accumulated in the F34 level to the H34 level, constructing a double populating mechanism for the upper laser level H34. A proof-of-principle experimental demonstration of the GSA (785 nm) and ESA (1470 nm) dual-wavelength pumped 2.3 μm Tm:LiYF4 (Tm:YLF) laser was realized. A maximum continuous-wave output power of 1.84 W at 2308 nm was achieved under 785 and 1470 nm dual-wavelength pumping, increased by 60% compared with the case of 785 nm single-wavelength pumping under the same resonator condition. Our work provides an efficient way to achieve higher output power from 2.3 μm Tm-doped lasers on the H34→H35 transition.
Chinese Optics Letters
  • Publication Date: Jun. 15, 2021
  • Vol.19 Issue, 9 091405 (2021)
Ultrafast Optics and Attosecond/high-field Physics
Generation of 601 fs pulse from an 8 kHz Nd:YVO4 picosecond laser by multi-pass-cell spectral broadening
Jiajun Song, Zhaohua Wang, Xianzhi Wang, Renchong Lü, Hao Teng, Jiangfeng Zhu, and Zhiyi Wei
Chinese Optics Letters
  • Publication Date: May. 26, 2021
  • Vol.19 Issue, 9 093201 (2021)
Visual Optics and Displays
High-speed playback of spatiotemporal division multiplexing holographic 3D video stored in a solid-state drive using a digital micromirror device
Kohei Suzuki, Minori Tao, Yuki Maeda, Hirotaka Nakayama, Ren Noguchi, Minoru Oikawa, Yuichiro Mori, Takashi Kakue, Tomoyoshi Shimobaba, Tomoyoshi Ito, and Naoki Takada
Chinese Optics Letters
  • Publication Date: May. 26, 2021
  • Vol.19 Issue, 9 093301 (2021)
Infrared and Terahertz Photonics
Liquid crystal integrated metamaterial for multi-band terahertz linear polarization conversion
Shitong Xu, Fei Fan, Hongzhong Cao, Yinghua Wang, and Shengjiang Chang
Chinese Optics Letters
  • Publication Date: Jun. 15, 2021
  • Vol.19 Issue, 9 093701 (2021)
Fiber Optics and Optical Communications
Compact vector twist sensor using a small period long period fiber grating inscribed with femtosecond laser
Fangcheng Shen, Xuewen Shu, Kaiming Zhou, Haiming Jiang, Hongyan Xia, Kang Xie, and Lin Zhang
Chinese Optics Letters
  • Publication Date: Jul. 13, 2021
  • Vol.19 Issue, 9 090601 (2021)
Optical Design and Fabrication
Micro-projection dynamic backlight for multi-view 3D display
Baichuan Zhao, Ruiying Huang, and Guojiao Lü
A micro-projection dynamic backlight for multi-view three-dimensional (3D) display is proposed. The proposed backlight includes a light emitting diodes (LEDs) array, a lenticular lens array, and a scattering film. The LED array, the lenticular lens, and the scattering film construct a micro-projection structure. In this structure, the LEDs in the array are divided into several groups. The light from each LED group can be projected to the scattering film by the lenticular lens and forms a series of bright stripes. The different LED groups have different horizontal positions, so these bright stripes corresponding to different LED groups also have different horizontal positions. Therefore, they can be used as a dynamic backlight. Because the distance between the LEDs array and the lenticular lens is much larger than the distance between the lenticular lens and the scattering films, the imaging progress will make the width of the bright stripes much smaller than that of the LEDs, and the pitch of the stripes is also decreased. According to the 3D display theory, the bright stripes with small width and pitch help to increase the number of views. Therefore, the proposed micro-projection dynamic backlight is very suitable for multi-view 3D display. An experimental prototype was developed, and the experimental results show that the micro-projection dynamic backlight can correctly complete the directional projection of the parallax images to form a 3D display.
Chinese Optics Letters
  • Publication Date: Jun. 02, 2021
  • Vol.19 Issue, 9 092201 (2021)
Optoelectronics
Avalanche mechanism analysis of 4H-SiC n-i-p and p-i-n avalanche photodiodes working in Geiger mode
Linlin Su, Weizong Xu, Dong Zhou, Fangfang Ren, Dunjun Chen, Rong Zhang, Youdou Zheng, and Hai Lu
Understanding detailed avalanche mechanisms is critical for design optimization of avalanche photodiodes (APDs). In this work, avalanche characteristics and single photon counting performance of 4H-SiC n-i-p and p-i-n APDs are compared. By studying the evolution of breakdown voltage as a function of incident light wavelength, it is confirmed that at the deep ultraviolet (UV) wavelength region the avalanche events in 4H-SiC n-i-p APDs are mainly induced by hole-initiated ionization, while electron-initiated ionization is the main cause of avalanche breakdown in 4H-SiC p-i-n APDs. Meanwhile, at the same dark count rate, the single photon counting efficiency of n-i-p APDs is considerably higher than that of p-i-n APDs. The higher performance of n-i-p APDs can be explained by the larger impact ionization coefficient of holes in 4H-SiC. In addition, this is the first time, to the best of our knowledge, to report single photon detection performance of vertical 4H-SiC n-i-p-n APDs.
Chinese Optics Letters
  • Publication Date: Jul. 08, 2021
  • Vol.19 Issue, 9 092501 (2021)
SNR improvement of 8.2 dB in a self-mixing laser diode interferometer by using the difference signal at the output mirrors [Invited] | Editors' Pick
Silvano Donati, and Michele Norgia
Chinese Optics Letters
  • Publication Date: Jul. 13, 2021
  • Vol.19 Issue, 9 092502 (2021)
Reviews
Instrumentation, Measurement, and Optical Sensing
Integrated Optics
Mode division multiplexing: from photonic integration to optical fiber transmission [Invited] | On the Cover
Jiangbing Du, Weihong Shen, Jiacheng Liu, Yufeng Chen, Xinyi Chen, and Zuyuan He
To overcome the capacity crunch of optical communications based on the traditional single-mode fiber (SMF), different modes in a few-mode fiber (FMF) can be employed for mode division multiplexing (MDM). MDM can also be extended to photonic integration for obtaining improved density and efficiency, as well as interconnection capacity. Therefore, MDM becomes the most promising method for maintaining the trend of “Moore’s law” in photonic integration and optical fiber transmission. In this tutorial, we provide a review of MDM works and cutting-edge progresses from photonic integration to optical fiber transmission, including our recent works of MDM low-noise amplification, FMF fiber design, MDM Si photonic devices, and so on. Research and application challenges of MDM for optical communications regarding long-haul transmission and short reach interconnection are discussed as well. The content is expected to be of important value for both academic researchers and industrial engineers during the development of next-generation optical communication systems, from photonic chips to fiber links.
Chinese Optics Letters
  • Publication Date: Aug. 26, 2021
  • Vol.19 Issue, 9 091301 (2021)
Lasers, Optical Amplifiers, and Laser Optics
Rare-earth ions-doped mid-infrared (2.7–3 µm) bulk lasers: a review [Invited] | Editors' Pick
Hongkun Nie, Feifei Wang, Junting Liu, Kejian Yang, Baitao Zhang, and Jingliang He
Mid-infrared (MIR) laser sources operating in the 2.7–3 µm spectral region have attracted extensive attention for many applications due to the unique features of locating at the atmospheric transparency window, corresponding to the “characteristic fingerprint” spectra of several gas molecules, and strong absorption of water. Over the past two decades, significant developments have been achieved in 2.7–3 µm MIR lasers benefiting from the sustainable innovations in laser technology and the great progress in material science. Here, we mainly summarize and review the recent progress of MIR bulk laser sources based on the rare-earth ions-doped crystals in the 2.7–3 µm spectral region, including Er3+-, Ho3+-, and Dy3+-doped crystalline lasers. The outlooks and challenges for future development of rare-earth-doped MIR bulk lasers are also discussed.
Chinese Optics Letters
  • Publication Date: Aug. 26, 2021
  • Vol.19 Issue, 9 091407 (2021)