Xiaohua Wang

2.0 μm room temperature CW operation of InGaAsSb/AlGaAsSb laser with asymmetric waveguide structure

The GaInAsSb/AlGaAsSb double quantum well lasers with an emission wavelength 2.0 μm, using the separate-confinement asymmetric waveguide, have been designed and fabricated, showing high quantum efficiency and high power conversion efficiency at continuous-wave operation mode. The threshold current density of the device is as low as 92 A/cm2. The internal loss coefficient and the internal quantum efficiency are 1.0 cm−1 and 86.1%, respectively. The 35% maximum power conversion efficiency (PCE) and narrow far-field patterned were achieved.

Large aperture vertical cavity surface emitting laser with distributed-ring contact

To overcome the serious current crowding effect in top-emitting vertical cavity surface emitting lasers (VCSELs) with large aperture, a distributed-ring-contact (DRC) VCSEL is proposed and demonstrated. A maximal cw light output power of more than 0.3 W and a wall-plug efficiency of 17.4% are achieved for a 300 μm-diameter VCSEL. The DRC VCSEL exhibits a more homogeneous emission profile, and the laser emits at 803.3 nm with a narrow spectrum (less than 0.2 nm FWHM).

High power 808 nm vertical cavity surface emitting laser with multi-ring-shaped-aperture structure

The carrier conglomeration effect has been one of the main problems in developing electrically pumped high power vertical cavity surface emitting laser (VCSEL) with large aperture. We demonstrate a high power 808 nm VCSEL with multi-ring-shaped-aperture (MRSA) to weaken the carrier conglomeration effect. Compared with typical VCSEL with single large aperture (SLA), the 300-μm-diameter VCSEL with MRSA has more uniform near field and far field patterns. Moreover, MRSA laser exhibits maximal CW light output power 0.3 W which is about 3 times that of SLA laser. And the maximal wall-plug efficiency of 17.4% is achieved, higher than that of SLA laser by 10%.

Optical properties of 1.3-\mum InAs/GaAs quantum dots grown by metal organic chemical vapor deposition

The optical properties of self-assembled InAs quantum dots (QDs) on GaAs substrate grown by metal-organic chemical vapor deposition (MOCVD) are reported. Photoluminescence (PL) measurements prove the good optical quality of InAs QDs, which are achieved using lower growth temperature and higher InAs coverage. At room temperature, the ground state peak wavelength of PL spectrum and full-width at half-maximum (FWHM) are 1305 nm and 30 meV, respectively, which are obtained as the QDs are finally capped with 5-nm In0.06Ga0.94As strain-reducing layer (SRL). The PL spectra exhibit two emission peaks at 1305 and 1198 nm, which correspond to the ground state (GS) and the excited state (ES) of the QDs, respectively.

Low-Density InAs Quantum Dots Growth by Molecular Beam Epitaxy

We investigate the growth of low-density(~4×108cm-2) InAs quantum dots (QDs) on GaAs by molecular beam epitaxy,with emission wavelength up to 1.3 µm at room temperature were achieved. The QDs density are sensitive to growth temperature,growth rate.The optical properties of the QDs annealing temperature used after spacer layer growth that is attributed to the suppressed In segregation from the QDs into the cap layer, reduced the strain in the QDs,significant decrease of integrated PL intensity was observed as the annealing temperature increases.

2.2 μm InGaAsSb/AlGaAsSb laser diode under continuous wave operating at room temperature

Abstract2.2 μm InGaAsSb/AlGaAsSb Sb-based type-I laser diodes (LDs) were fabricated, with cavity lengths of 1000 μm and stripe width of 150 μm. The high output performance was achieved with the threshold current density of the device is as low as 187 A/cm2, slope efficiency of 0.2 W/A, and vertical and parallel divergent angles ϑ⊥ = 42° and ϑ| = 10°, respectively. The continuous wave operating up to 320 mW at room temperature (RT) were achieved.

2.1μm Room Temperature Continuous Waves Operation of InGaAsSb-AlGaAsSb Double-Quantum Well Laser

The GaInAsSb-AlGaAsSb double quantum well lasers with an emission wavelength around 2.1μm, shown high quantum efficiency and high power conversion efficiency at continuous-wave power output. The threshold current density and the external quantum efficiency of the device were 130mA/cm2 and 36.1%, respectively. The 15% maximum power conversion efficiency (PCE) were achieved from laser operating about 2.1μm wavelength.

2.0 µm multiple quantum-wells InGaAsSb/AlGaAsSb laser diode operating continuous wave at room temperature

The multiple quantum wells (MQWs) InGaAsSb/AlGaAsSb laser diodes (LDs) with an emission wavelength around 2.0µm were designed and fabricated by molecular beam epitaxy (MBE). The good performance of LD was achieved, with the low threshold current of 225 mA, and the slope efficiency of 0.23 W/A, respectively. The maximum outpower of 16 mW at 500 mA drive current was obtained at room temperature(RT).

Study on high quality InGaAsSb/AlGaAsSb MQWs grown by molecular beam epitaxy

In this work, the Type I InGaAsSb/AlGaAsSb multiple-quantum-wells (MQWs) has been grown by molecular beam epitaxy (MBE). The comprised five InGaAsSb quantum wells are embedded in AlGaAsSb barriers, the barriers/QWs periodicity matches to GaSb substrates, and satellite peaks indicate a good crystalline quality. The central peak emission wavelength is around 2.0 µm at room temperature by photoluminescence (PL), with a full-width at half-maximum (FWHM) of 39 meV.

High performance blue light-emitting diodes on patterned Si substrate

High quality crack-free GaN layers were successfully grown and the InGaN/GaN based blue LEDs fabricated on patterned Si (111) substrates. In addition to using the patterned growth technique, thin AlN and SiNx interlayers grown at high temperatures were also employed to partially release the residual stress and to further improve the crystalline quality. 300 µm square blue LEDs fabricated on the islands, without thinning and package, exhibited a high output power of around 0.68 mW at a drive current of 20 mA.