S. Y. Zhang

Bio: S. Y. Zhang is an academic researcher. The author has contributed to research in topics: Quantum well & Molecular beam epitaxy. The author has an hindex of 2, co-authored 2 publications receiving 67 citations.

GaAs-based room-temperature continuous-wave 1.59 {mu}m GaInNAsSb single-quantum-well laser diode grown by molecular-beam epitaxy

Abstract: Starting from the growth of high-quality 1.3μmGaInNAs∕GaAs quantum well (QW), the QW emission wavelength has been extended up to 1.55μm by a combination of lowering growth rate, using GaNAs barriers and incorporating some amount of Sb. The photoluminescence properties of 1.5μm range GaInNAsSb∕GaNAs QWs are quite comparable to the 1.3μm QWs, revealing positive effect of Sb on improving the optical quality of the QWs. A 1.59μm lasing of a GaInNAsSb∕GaNAs single-QW laser diode is obtained under continuous current injection at room temperature. The threshold current density is 2.6kA∕cm2 with as-cleaved facet mirrors.

1.55 mu m GaInNAs resonant-cavity-enhanced photodetector grown on GaAs

Abstract: We report the design, growth, fabrication, and characterization of a GaAs-based resonant-cavity-enhanced (RCE) GaInNAs photodetector operating at 1.55μm. The structure of the device was designed using a transfer-matrix method (TMM). By optimizing the molecular-beam epitaxy growth conditions, six GaInNAs quantum wells were used as the absorption layers. Twenty-five (25)- and 9-pair GaAs∕AlAs-distributed Bragg reflectors were grown as the bottom and top mirrors. At 1.55μm, a quantum efficiency of 33% with a full width at half maximum of 10nm was obtained. The dark current density was 3×10−7A∕cm2 at a bias of 0V and 4.3×10−5A∕cm2 at a reverse bias of 5V. The primary time response measurement shows that the device has a rise time of less than 800ps.

All-fiber switchable orbital angular momentum mode-locked laser based on TM-FBG

Abstract: In this paper, a simple all-fiber switchable orbital angular momentum (OAM) mode-locked laser is demonstrated. The laser is mainly composed of a single-mode fiber Bragg grating (FBG), a two-mode fiber Bragg grating (TM-FBG), a two-mode circulator, and a nonlinear polarization rotation system. The coupling properties of the TM-FBG are verified, and an OAM mode-locked laser with switchable topological charges of −1, 0, and 1 is realized. When the pump power is 462 mW, the output powers of the fundamental mode and OAM±1 mode-locked lasers are 9.750 and 2.707 mW, respectively. Their repetition rates are both 10.16 MHz, and the signal-to-noise ratios are 60 and 59 dB. When the pump power is increased to 774 mW, the mode-locked laser can operate in the single-pulse, double-pulse, and triple-pulse states. Their output powers are 5.1, 7.4, and 10.1 mW, respectively. The OAM mode purity higher than 98.9% is experimentally realized.

A multi-spectral and polarization-selective surface-plasmon resonant mid-infrared detector

Abstract: We demonstrate a multi-spectral polarization sensitive mid-infrared dots-in-a-well (DWELL) photodetector utilizing surface-plasmonic resonant elements, with tailorable frequency response and polarization selectivity. The resonant responsivity of the surface-plasmon detector shows an enhancement of up to 5 times that of an unpatterned control detector. As the plasmonic resonator involves only surface patterning of the top metal contact, this method is independent of light-absorbing material and can easily be integrated with current focal plane array processing for imaging applications.

A multispectral and polarization-selective surface-plasmon resonant midinfrared detector

Abstract: We demonstrate a multispectral polarization sensitive midinfrared dots-in-a-well photodetector utilizing surface-plasmonic resonant elements, with tailorable frequency response and polarization selectivity. The resonant responsivity of the surface-plasmon detector shows an enhancement of up to five times that of an unpatterned control detector. As the plasmonic resonator involves only surface patterning of the top metal contact, this method is independent of light-absorbing material and can easily be integrated with current focal plane array processing for imaging applications.

Growth and characteristics of ultralow threshold 1.45 μm metamorphic InAs tunnel injection quantum dot lasers on GaAs

Abstract: The molecular beam epitaxial growth and characteristics of 1.45μm metamorphic InAs quantum dot tunnel injection lasers on GaAs have been studied. Under optimized growth conditions, the quantum dots exhibit photoluminescence linewidths ∼30meV and high intensity at room temperature. The lasers are characterized by ultralow threshold current (63A∕cm2), large frequency response (f−3dB=8GHz), and near-zero α parameter and chirp.

Development of GaInNAsSb alloys : Growth, band structure, optical properties and applications

Abstract: In the past few years, GaInNAsSb has been found to be a potentially superior material to both GaInNAs and InGaAsP for communications wavelength laser applications. It has been observed that due to the surfactant role of antimony during epitaxy, higher quality material can be grown over the entire 1.2 – 1.6 µm range on GaAs substrates. In addition, it has been discovered that antimony in GaInNAsSb also works as a constituent that significantly modifies the valence band. These findings motivated a systematic study of GaInNAsSb alloys with widely varying compositions. Our recent progress in growth and materials development of GaInNAsSb alloys and our fabrication of 1.5 – 1.6 µm lasers are discussed in this paper. We review our recent studies of the conduction band offset in (Ga,In) (N,As,Sb)/GaAs quantum wells and discuss the growth challenges of GaInNAsSb alloys. Finally, we report record setting long wavelength edge emitting lasers and the first monolithic VCSELs operating at 1.5 µm based on GaInNAsSb QWs grown on GaAs. Successful development of GaInNAsSb alloys for lasers has led to a much broader range of potential applications for this material including: solar cells, electroabsorption modulators, saturable absorbers and far infrared optoelectronic devices and these are also briefly discussed in this paper.

1.58 mu m InGaAs quantum well laser on GaAs

Abstract: We demonstrate the 1.58 mu m emission at room temperature from a metamorphic In0.6Ga0.4As quantum well laser grown on GaAs by molecular beam epitaxy. The large lattice mismatch was accommodated through growth of a linearly graded buffer layer to create a high quality virtual In0.32Ga0.68As substrate. Careful growth optimization ensured good optical and structural qualities. For a 1250x50 mu m(2) broad area laser, a minimum threshold current density of 490 A/cm(2) was achieved under pulsed operation. This result indicates that metamorphic InGaAs quantum wells can be an alternative approach for 1.55 mu m GaAs-based lasers. (C) 2007 American Institute of Physics.