Zhuoran Wang

Bio: Zhuoran Wang is an academic researcher from University of Electronic Science and Technology of China. The author has contributed to research in topics: Semiconductor ring laser & Semiconductor laser theory. The author has an hindex of 17, co-authored 101 publications receiving 800 citations. Previous affiliations of Zhuoran Wang include University of Bristol & Tianjin University.

Storing 2 Bits of Information in a Novel Single Semiconductor Microring Laser Memory Cell

Abstract: An optical memory cell that has four distinctive states, therefore storing 2 bits of information optically, is demonstrated by utilizing a novel single semiconductor microring laser with a retro-reflector cavity. To our best knowledge, it is the first time the combination of two directional and two wavelength states with a single semiconductor ring laser of only 20 times 62 mum2 in size has been demonstrated in which room-temperature continuous-wave operation is realized. These states can be easily written by corresponding optical inputs with low optical energy of ~ 1.56 fJ and rapid access time of ~70 ps suitable for 10 Gb/s or higher data rates.

All-Optical Response of Semiconductor Ring Laser to Dual-Optical Injections

Abstract: The all-optical response of a semiconductor ring laser (SRL) to two optical injections is characterized. Once the lasing direction is locked by one optical injection, the SRL direction of operation can be switched by another optical injection into the counterpropagating direction. The switching process manifests a typical bistable hysteresis loop, with its width and switching thresholds variable by the first injection power. Extremely sharp transition has been measured which confirms the potential of the SRL for all-optical regeneration applications.

Unidirectional Bistability in AlGaInAs Microring and Microdisk Semiconductor Lasers

Abstract: We report on room-temperature continuous-wave operation and single-mode lasing of microdisk and microring lasers with radii as small as 7 mum. The waveguide sidewall roughness was minimized by an optimized fabrication process using hydrogen silsesquioxane e-beam resist and Cl 2-CH 3-H 2 inductively coupled plasma etching. The devices show unidirectional bistability between the counterpropagating modes for radii larger than 30 mu m and a strong hybrid output polarization for radii smaller than 15 mum with a transverse-magnetic component of approximately 30%.

Integrated Small-Sized Semiconductor Ring Laser With Novel Retro-Reflector Cavity

Abstract: We have successfully designed and fabricated 1.55-mum semiconductor ring lasers with novel parabolic mirror retro-reflector cavities. The parabolic mirror is designed by means of ray-tracing and finite-difference time-domain to optimize its shape and position. The fabricated devices, with a range of sizes down to an equivalent circular ring radius of 16 mum, operate in continuous-wave mode at room temperature. Threshold current of 22 mA and output power up to 140 muW have been achieved for the smallest device. These devices are suitable for high-speed all-optical signal processing and digital photonic functions.

An ultra-small, low power all-optical flip-flop memory on a silicon chip

Abstract: Ultra-small, low-power, all-optical switching and memory elements, such as all-optical flip-flops, as well as photonic integrated circuits of many such elements, are in great demand for all-optical signal buffering, switching and processing. Silicon-on-insulator is considered to be a promising platform to accommodate such photonic circuits in large-scale configurations. Through heterogeneous integration of InP membranes onto silicon-on-insulator, a single microdisk laser with a diameter of 7.5 µm, coupled to a silicon-on-insulator wire waveguide, is demonstrated here as an all-optical flip-flop working in a continuous-wave regime with an electrical power consumption of a few milliwatts, allowing switching in 60 ps with 1.8 fJ optical energy. The total power consumption and the device size are, to the best of our knowledge, the smallest reported to date at telecom wavelengths. This is also the only electrically pumped, all-optical flip-flop on silicon built upon complementary metal-oxide semiconductor technology. Scientists demonstrate that a single 7.5-μm-diameter microdisk laser coupled to a silicon-on-insulator wire waveguide can work as an all-optical flip-flop memory. Under a continuous bias of 3.5 mA, flip-flop operation is demonstrated using optical triggering pulses of 1.8 fJ and with a switching time of 60 ps. This device is attractive for on-chip all-optical signal buffering, switching, and processing.

Density-matrix theory of semiconductor lasers with relaxation broadening model - Gain and gain-suppression in semiconductor lasers

Abstract: The density-matrix theory of semiconductor lasers with relaxation broadening model is finally established by introducing theoretical dipole moment into previously developed treatments. The dipole moment is given theoretically by the k . p method and is calculated for various semiconductor materials. As a result, gain and gain-suppression for a variety of crystals covering wide wavelength region are calculated. It is found that the linear gain is larger for longer wavelength lasers and that the gain-suppression is much larger for longer wavelength lasers, which results in that single-mode operation is more stable in long-wavelength lasers than in shorter-wavelength lasers, in good agreement with the experiments.

Photonic Crystal Fiber-Based Surface Plasmon Resonance Sensor with Selective Analyte Channels and Graphene-Silver Deposited Core

Abstract: We propose a surface plasmon resonance (SPR) sensor based on photonic crystal fiber (PCF) with selectively filled analyte channels. Silver is used as the plasmonic material to accurately detect the analytes and is coated with a thin graphene layer to prevent oxidation. The liquid-filled cores are placed near to the metallic channel for easy excitation of free electrons to produce surface plasmon waves (SPWs). Surface plasmons along the metal surface are excited with a leaky Gaussian-like core guided mode. Numerical investigations of the fiber’s properties and sensing performance are performed using the finite element method (FEM). The proposed sensor shows maximum amplitude sensitivity of 418 Refractive Index Units (RIU−1) with resolution as high as 2.4 × 10−5 RIU. Using the wavelength interrogation method, a maximum refractive index (RI) sensitivity of 3000 nm/RIU in the sensing range of 1.46–1.49 is achieved. The proposed sensor is suitable for detecting various high RI chemicals, biochemical and organic chemical analytes. Additionally, the effects of fiber structural parameters on the properties of plasmonic excitation are investigated and optimized for sensing performance as well as reducing the sensor’s footprint.

Enhanced Modulation Characteristics of Optical Injection-Locked Lasers: A Tutorial

Abstract: In this paper a tutorial of optical injection locking of semiconductor lasers is given, with particular emphasis on the enhancement of system parameters. Furthermore, physical intuition of each parameter enhancement is explained and practical design rules and trends are also shown.