High-performance millimeter-scale silicon grating emitters for beam steering applications
Ze Chen, Haibin Lü, Yanfeng Chen, and Xiaoping Liu
A 2-mm-long silicon-on-insulator grating emitter with a narrow angular full width at half-maximum (FWHM) and a high sideband suppression ratio (SSR) is proposed and designed. It consists of a Si3N4/Si grating with an approximate Gaussian emission profile along the grating length, which aims to reduce the sidelobe intensity of the scanning light in the far-field, thereby improving the resolution of the longitudinal steering resolution of the light detection and ranging (lidar). Numerical analysis shows that the angular FWHM of the emitted beam could be as low as 0.026° for a grating length of 2.247 mm and the input TE-like waveguide mode at 1550 nm, and the SSR could be more than 32.622 dB. Moreover, this Si3N4/Si grating exhibits a favorable fabrication error tolerance when considering the width and length variation of the Si3N4 overlayer in practice. Our design offers a promising platform for realizing integrated optical phased arrays for the long-distance solid-state lidar.
  • Sep. 29, 2022
  • Chinese Optics Letters
  • Vol. 20, Issue 12, 121301 (2022)
  • DOI:10.3788/COL202220.121301
Hong–Ou–Mandel interference linking independent room-temperature quantum memories | Editors' Pick
Chao-Ni Zhang, Hang Li, Jian-Peng Dou, Feng Lu, Hong-Zhe Yang, Xiao-Ling Pang, and Xian-Min Jin
To realize a large-scale quantum network, both quantum memory and the interference of retrieved indistinguishable photons are essentially required to perform multi-photon synchronization and quantum-interference-mediated entanglement swapping. Significant progress has been achieved in low-temperature and well-isolated systems. However, linking independent quantum memories at room temperature remain challenging. Here, we present an experimental demonstration of Hong–Ou–Mandel interference between single photons from two independent room-temperature quantum memories. We manage to simultaneously operate two such quantum memories and individually obtain a memory-built-in quantum correlation of Stokes and anti-Stokes photons by a far-off-resonance Duan–Lukin–Cirac–Zoller protocol. We also successfully enhance the Hong–Ou–Mandel interference rate up to about 15 times by increasing each photon rate, which is achieved by coordinating two quantum memories with a repeat-until-success fashion. We observe the visibility of quantum interference up to 75.0% without reduction of any background noise, well exceeding the classical limit of 50%. Our results, together with its straightforward, broadband, and room-temperature features, open up a promising way towards realizing large-scale quantum networks at ambient conditions.
  • Sep. 29, 2022
  • Photonics Research
  • Vol. 10, Issue 10, 2388 (2022)
  • DOI:10.1364/PRJ.463404
Compact Thomson Scattering Source Based on a Mixed Injection Assisted Laser Wakefield Accelerator
Fang Tan, Xiao Hui Zhang, Bin Zhu, Gang Li, Yu Chi Wu, Ming Hai Yu, Yue Yang, Yong Hong Yan, Wei Fan, Ke Gong Dong, Feng Lu, Tian Kui Zhang, Yu Qiu Gu, and Yongtao Zhao
In order to establish a compact all-optical Thomson scattering source, experimental studies were conducted on the 45 TW Ti: sapphire laser facility. By including a steel wafer, mixed gas, and plasma mirror into a double-exit jet, several mechanisms, such as shock-assisted ionization injection, ionization injection, and driving laser reflection, were integrated into one source. So, the source of complexity was remarkably reduced. Electron bunches with central energy fluctuating from 90 to 160 MeV can be produced. Plasma mirrors were used to reflect the driving laser. The scattering of the reflected laser on the electron bunches led to the generation of X-ray photons. Through comparing the X-ray spots under different experimental conditions, it is confirmed that the X-ray photons are generated by Thomson scattering. For further application, the energy spectra and source size of the Thomson scattering source were measured. The unfolded spectrum contains a large amount of low-energy photons besides a peak near 67 keV. Through importing the electron energy spectrum into the Monte Carlo simulation code, the different contributions of the photons with small and large emitting angles can be used to explain the origin of the unfolded spectrum. The maximum photon energy extended to about 500 keV. The total photon production was 107/pulse. The FWHM source size was about 12 μm.
  • Sep. 28, 2022
  • Laser and Particle Beams
  • Vol. 2022, Issue 3, 4132792 (2022)
  • DOI:10.1155/2022/4132792
Sibling Journal to Advanced Photonics: Advanced Photonics Nexus
Xiao-Cong (Larry) Yuan, Anatoly Zayats, and Weibiao Chen
  • Sep. 28, 2022
  • Advanced Photonics Nexus
  • Vol. 1, Issue 1, 010101 (2022)
  • DOI:10.1117/1.APN.1.1.010101
Systematic investigation of millimeter-wave optic modulation performance in thin-film lithium niobate
Yiwen Zhang, Linbo Shao, Jingwei Yang, Zhaoxi Chen, Ke Zhang, Kam-Man Shum, Di Zhu, Chi Hou Chan, Marko Lončar, and Cheng Wang
Millimeter-wave (mmWave) band (30–300 GHz) is an emerging spectrum range for wireless communication, short-range radar, and sensor applications. mmWave-optic modulators that could efficiently convert mmWave signals into the optical domain are crucial components for long-haul transmission of mmWave signals through optical networks. At these ultrahigh frequencies, however, the modulation performances are highly sensitive to the transmission line loss as well as the velocity- and impedance-matching conditions, while precise measurements and modeling of these parameters are often non-trivial. Here we present a systematic investigation of the mmWave-optic modulation performances of thin-film lithium niobate modulators through theoretical modeling, electrical verifications, and electro-optic measurements at frequencies up to 325 GHz. Based on our experimentally verified model, we demonstrate thin-film lithium niobate mmWave-optic modulators with a measured 3-dB electro-optic bandwidth of 170 GHz and a 6-dB bandwidth of 295 GHz. The device also shows a low RF half-wave voltage of 7.3 V measured at an ultrahigh modulation frequency of 250 GHz. This work provides a comprehensive guideline for the design and characterization of mmWave-optic modulators and paves the way toward future integrated mmWave photonic systems for beyond-5G communication and radar applications.
  • Sep. 28, 2022
  • Photonics Research
  • Vol. 10, Issue 10, 2380 (2022)
  • DOI:10.1364/PRJ.468518
Phase regimes of parity-time-symmetric coupled-ring systems at exceptional points
Zhuang Ma, Xiaoyan Zhou, and Lin Zhang
The optical coupled resonant system consisting of an integrated resonator with gain and a resonator with loss provides an excellent platform to create exceptional points (EPs) in non-Hermitian systems. Most previous studies have focused on the striking intensity feature of EPs, but its phase response is seldom investigated. In this work, we present a thorough study on the phase response of an EP system. Intriguingly, the phase response exhibits distinct behavior depending on the ordering of the ring resonators: when the input light in a bus waveguide is coupled directly or indirectly to the ring with a gain, the phase response is featured by nonmonotonic transition and 2π monotonic transition, respectively. We also prove that the newly identified phase features are theoretically guaranteed. These phase responses produce unique group delays that have never been found in other coupled resonant systems. The results deepen our understanding on EPs in non-Hermitian systems and are potentially useful for practical applications exploiting phase features.
  • Sep. 28, 2022
  • Photonics Research
  • Vol. 10, Issue 10, 2374 (2022)
  • DOI:10.1364/PRJ.465966
Ultra-high-linearity integrated lithium niobate electro-optic modulators | Editors' Pick
Hanke Feng, Ke Zhang, Wenzhao Sun, Yangming Ren, Yiwen Zhang, Wenfu Zhang, and Cheng Wang
Integrated lithium niobate (LN) photonics is a promising platform for future chip-scale microwave photonics systems owing to its unique electro-optic properties, low optical loss, and excellent scalability. A key enabler for such systems is a highly linear electro-optic modulator that could faithfully convert analog electrical signals into optical signals. In this work, we demonstrate a monolithic integrated LN modulator with an ultra-high spurious-free dynamic range (SFDR) of 120.04 dB·Hz4/5 at 1 GHz, using a ring-assisted Mach–Zehnder interferometer configuration. The excellent synergy between the intrinsically linear electro-optic response of LN and an optimized linearization strategy allows us to fully suppress the cubic terms of third-order intermodulation distortions (IMD3) without active feedback controls, leading to ∼20 dB improvement over previous results in the thin-film LN platform. Our ultra-high-linearity LN modulators could become a core building block for future large-scale functional microwave photonic integrated circuits by further integration with other high-performance components like low-loss delay lines, tunable filters, and phase shifters available on the LN platform.
  • Sep. 28, 2022
  • Photonics Research
  • Vol. 10, Issue 10, 2366 (2022)
  • DOI:10.1364/PRJ.464650
Taming quantum dots’ nucleation and growth enables stable and efficient blue-light-emitting devices
Zhiwei Ma, Junxia Hu, Liping Tang, and Bingbing Lyu
Controlling quantum dots’ emission, nanostructure, and energy level alignment to achieve stable and efficient blue emission is of great significance for electroluminescence devices but remains a challenge. Here, a series of blue ZnCdSeS/ZnS quantum dots was optimized in preparation by taming their nucleation and growth kinetics. Controlling anion precursor reactive properties to modulate quantum dots’ nucleation and growth tailors their alloy core and continuous gradient energy band nanostructure. These results not only elevate the thermal stability of blue quantum dots but also further enhance the injection/transportation of carriers and improve the radiative recombination efficiency in the device. The blue ZnCdSeS/ZnS quantum dots applied in light-emitting devices show superior performance, including maximum current efficiency and external quantum efficiency of, respectively, 8.2 cd/A and 15.8% for blue, 2.6 cd/A and 10.0% for blue-violet, and 10.9 cd/A and 13.4% for sky-blue devices. The blue and sky-blue devices exhibit lifetimes of more than 10,000 h. The proposed methodology for tailoring quantum dots is expected to pave new guidelines for further facilitating visible optoelectronic device exploration.
  • Sep. 28, 2022
  • Photonics Research
  • Vol. 10, Issue 10, 2359 (2022)
  • DOI:10.1364/PRJ.462852
Optics Physics Geography All Subjects

Special lssue

Special Issue on Relativistic Laser Plasma Interaction (RLPI) Diagnostics and Instrumentation (2022)

Submission Open:1 June 2022; Submission Deadline: 31 December 2022

Editor (s): Joerg Schreiber, Rodrigo Lopez-Martens, Lieselotte Obst-Huebl, Jianhui Bin

Future Control Systems and Machine Learning at High Power Laser Facilities (2022)

Submission Open:1 March 2022; Submission Deadline: 30 October 2022

Editor (s): Andreas Döpp, Matthew Streeter, Scott Feister, Hyung Taek Kim, Charlotte Palmer