Showing papers on "Semiconductor optical gain published in 2018"

Optical Properties of 2D Semiconductor WS2

Abstract: 2D semiconductor tungsten disulfide (WS2) attracts significant interest in both fundamental physics and many promising applications such as light emitters, photodetectors/sensors, valleytronics, and flexible nanoelectronics, due to its fascinating optical, electronic, and mechanical properties. Herein, basic exciton properties of monolayer WS2 are reviewed including neutral excitons, charged excitons, bounded excitons, biexcitons, and the effects of electrostatic gating, chemical doping, strain, magnetic field, circular polarized light, and substrate on these excitonic structures. Besides basic excitonic emission, single-photon emission, exciton–polaritons, and stimulated emission in monolayer WS2 are also discussed. The understanding of these optical phenomena is critical for the development of potential optical applications in electronic and optoelectronic devices. Finally, a summary and future prospective of the challengers and developments regarding 2D semiconductor WS2 is presented.

Integrated Semiconductor Laser Optical Phase Lock Loops

Abstract: An Optical Phase Lock Loop (OPLL) is a feedback control system that allows the phase stabilization of a laser to a reference laser with absolute but adjustable frequency offset Such phase and frequency locked optical oscillators are of great interest for sensing, spectroscopy, and optical communication applications, where coherent detection offers advantages of higher sensitivity and spectral efficiency than can be achieved with direct detection As explained in this paper, the fundamental difficulty in realising an OPLL is related to the limitations on loop bandwidth and propagation delay as a function of laser linewidth In particular, the relatively wide linewidth of semiconductor lasers requires short delay, which can only be achieved through shortening of the feedback path, which is greatly facilitated through photonic integration This paper reviews the advances in the development of semiconductor laser-based OPLLs and describes how improvements in performance have been enabled by improvements in photonic integration technology We also describe the first OPLL created using foundry fabricated photonic integrated circuits and off-the-shelf electronic components Stable locking has been achieved for offset frequencies between 4 and 12 GHz with a heterodyne phase noise below –100 dBc/Hz at 10 kHz offset This is the highest performance yet reported for a monolithically integrated OPLL and demonstrates the attractiveness of the foundry fabrication approach

Directly Modulated Semiconductor Lasers

Abstract: This paper presents a review and discussion of the directly modulated semiconductor lasers and their applications to optical communications and microwave photonics. A detailed and comprehensive demonstration of directly modulated semiconductor lasers from development history to specific techniques on measurement, analysis, and packaging is provided for the first time to the best of our knowledge. A few typical applications based on directly modulated lasers are also illustrated, such as optical fiber communications, free-space optical communications and microwave photonics. Future directions of research are also highlighted.

Fast and Robust Method for Measuring Semiconductor Optical Amplifier Gain

Abstract: In this paper, we present a new, robust multipoint fitting method for gain measurement with a metric for quality estimation of the procedure. The method is able to identify the deleterious effect of imperfections within the test structures, is tolerant to optical coupling errors and is well suited to high throughput, generic, automated testing of semiconductor optical amplifiers. Gain is estimated in a range of pump current densities over multiple spectral bands from 1400 to 1600 nm with a standard error in the order of 1/cm.

Self-Sustained Laser Pulsation in Active Optomechanical Devices

Abstract: We developed a model for an active optomechanical cavity embedding a semiconductor optical gain medium in the presence of dispersive and dissipative optomechanical couplings. Radiation pressure drives the mechanical oscillation and the back-action occurs due to the mechanical modulation of the cavity loss rate. Our numerical analysis utilizing this model shows that, even in a wideband gain material, such mechanism couples the mechanical vibration with the laser relaxation oscillation, enabling an effect of self-pulsed laser emission. In order to investigate this effect, we propose a bullseye-shaped device with high confinement of both the optical and the mechanical modes at the edge of a disk combined with a dissipative structure in its vicinity. The dispersive interaction is promoted by the strong photoelastic effect while the dissipative mechanism is governed by the boundary motion mechanism, enhanced by near-field interaction with the absorptive structure. This hybrid optomechanical device is shown to lead sufficient coupling for the experimental demonstration of the self-pulsed emission.

Theoretical Analysis of a Feedback Insensitive Semiconductor Ring Laser Using Weak Intracavity Isolation

Abstract: External optical feedback can severely deteriorate the performance of semiconductor lasers. This paper proposes an integrated laser design that can withstand tens of percent of off-chip feedback, without requiring the integration of magneto-optic materials. The proposed laser consists of a ring cavity with a weak intracavity optical isolator. Sufficient gain difference between clockwise and counter-clockwise modes leads to unidirectional laser oscillation. Any reflected light is returned to a mode that is below threshold. This significantly reduces interactions between the feedback and the lasing mode. A rate-equation analysis is presented to show that the rin changes less than a factor 2 when less than −0.1 dB of the light is fed back into the laser and when intracavity isolation is 10 dB. Linewidth and optical output power change approximately 0.1% for these values.

Surface Plasmon Polariton Waveguide by Bottom and Top of Graphene

Abstract: Semiconductor surface plasmon polariton (SPP) waveguide has unique optical properties and compatibility with existing integrated circuit manufacturing technology; thus, SPP devices of semiconductor materials have wide application potential. In this study, a new integrated graphene SPP waveguide is designed using the bottom and top roles of graphene. Moreover, a T waveguide structure is designed by InGaAs of semiconductor gain, with rectangular GaAs material on both sides. The structure adopts light to stimulate the SPP, where its local area is enhanced by the interaction between two interface layers and a semiconductor gain and where its frequency can be adjusted by the thickness of the graphene. Characteristic analysis reveals the coupling between the T semiconductor gain and the SPP mode. The propagation distance of the waveguide can reach 75 cm, the effective mode field is approximately 0.0951λ 2, the minimum of gain threshold is approximately 2992.7 cm−1, and the quality factor (FOM) can reach 180. The waveguide structure which provides stronger localization can be compatible with several optical and electronic nanoscale components. That means, it can provide light for surface plasmon circuit and also can provide a great development in the low-threshold nanolaser.