Liu Shaoqing

Influence of window layer thickness on double layer antireflection coating for triple junction solar cells

The optimization of a SiO2/TiO2, SiO2/ZnS double layer antireflection coating (ARC) on Ga0.5In0.5P/In0.02Ga0.98As/Ge solar cells for terrestrial application is discussed. The Al0.5In0.5P window layer thickness is also taken into consideration. It is shown that the optimal parameters of double layer ARC vary with the thickness of the window layer.

Design and fabrication of a high-performance evanescently coupled waveguide photodetector

In this paper, we present the design, fabrication, and measurement of an evanescently coupled waveguide photodetector operating at 1.55 μm, which mainly comprises a diluted waveguide, a single-mode rib waveguide and a p—i—n photodiode with an extended optical matching layer. The optical characteristics of this structure are studied by using a three-dimensional finite-difference time-domain (3D FDTD) method. The photodetector exhibits a high 3-dB bandwidth of more than 35 GHz and a responsivity of 0.291 A/W at 1550 nm directly coupled with a cleaved fiber. Moreover, a linear response of more than 72-mW optical power is achieved, where a photocurrent of more than 21 mA is obtained at a reverse bias voltage of 3 V.

Tunable Metamorphic Resonant Cavity Enhanced InGaAs Photodetectors Grown on GaAs Substrates

Tunable metamorphic InGaAs partially depleted absorber photodiodes with resonant cavity enhanced structure are fabricated on GaAs substrate. Dark-current densities of 7.2 × 10−7 A/cm2 at 0 V and 3.6 × 10−4 A/cm2 at −5 V, a high quantum efficiency of 74.4% at 1546 nm, and a 3-dB bandwidth up to 12 GHz are achieved. The full width at half maximum of the detector is about 16 nm. Furthermore, through thermal tuning, the peak wavelength red shifts from 1527 nm to 1544 nm, and a tuning range of 17 nm is realized without fabricating extra tuning electrodes.

High Quality Pseudomorphic In 0.24 GaAs/GaAs Multi-Quantum-Well and Large-Area Transmission Electro-Absorption Modulators

The good quality of 200 pairs of highly strained In0.24GaAs/GaAs multi-quantum-well (MQW) structure is demonstrated by the x-ray diffraction and photoluminescence curves. Large-area modulators based on the pseudomorphic In0.24GaAs/GaAs MQW are designed and fabricated successfully, where the diameters are not less than 3 mm and the working wavelength is extended to 1064 nm. The single pass modulation depth is demonstrated to be 0.34 at 1064 nm at a reverse voltage of 80 V.