Impact of diode facet reflectivity on the fiber grating external cavity semiconductor laser

The scattering matrix method is used to analyze the multiple reflection effect between the laser diode facet and the fiber grating facet by considering the fiber grating external cavity laser diode (FGECL) as a four-mirror cavity laser. When neglecting other important parameters such as butt-coupling distance between the diode and the fiber facets, coupling efficiency, external cavity length, it is shown that low reflectivity is not a crucial factor for the laser characteristics such as SMSR. Experimentally high SMSR fiber grating external cavity laser is fabricated with a relatively large residual facet reflectivity (about 1%), which is coincident with our simulation results.

High performance resonant tunneling diode on a new material structure

A new material structure with Al0.22Ga0.78As/In0.15Ga0.85As/GaAs emitter spacer layer and GaAs/In0.15Ga0.85As/GaAs well for resonant tunneling diodes is designed and the corresponding device is fabricated. RTDs DC characteristics are measured at room temperature. Peak-to-valley current ratio (PVCR) is 7.44 for RTD Analysis on these results suggests that the material structure will be helpful to improve the quality, of RTD.

Low-threshold diode-pumped CW passively mode-locked Nd:YVO4 lase

A low-threshold passively continuous-wave (CW) mode-locked Nd:YVO4 solid-state laser was demonstrated by use of a semiconductor saturable absorber mirror (SESAM). The threshold for continuous-wave mode-locked is relatively low, about 2.15 W. The maximum average output power was 2.12 W and the optical to optical conversion efficiency was about 32%. The pulse width was about 15 ps with the repetition rate of 105 MHz. (C) 2008 Elsevier GmbH. All rights reserved.

Evaluating 0.53 eVGaInAsSbthermophotovoltaic diode based on an analytical absorption model

Radiant heat conversion performance dominated by the active layer of Ga0.84In0.16As0.14Sb0.86 diode has been systematically investigated based on an analytic absorption spectrum, which is suggested here by numerically fitting the limited experimental data. For the concerned diode configuration, our calculation demonstrates that the optimal base doping is 3-4 x 10(17) cm(-3), which is less sensitive to the variation of the external radiation spectrum. Given the scarcity of the alloy elements, an economical device configuration of the 0.2-0.6 mu m emitter and the 4-6 mu m base would be particularly acceptable because the corresponding conversion efficiency cannot exhibit discouraging degradation in comparison to the one for the optimal structure, the thickness of which may be up to 10 mu m. More importantly, the method we suggested here to calculate alloy absorption can be easily transferred to other composition, thus bringing great convenience for design or optimization of the optoelectronic device formed by these alloys.

An asymmetric broad waveguide structure for a 0.98-μm high-conversion-efficiency diode laser

A novel asymmetric broad waveguide diode laser structure was designed for high power conversion efficiency (PCE). The internal quantum efficiency, the series resistance, and the thermal resistance were theoretically optimized. The series resistance and the thermal resistance were greatly decreased by optimizing the thickness of the P-waveguide and the P-cladding layers. The internal quantum efficiency was increased by introducing a novel strain-compensated GaAs_0.9P_0.1/InGaAs quantum well. Experimentally, a single 1-cm bar with 20% fill factor and 900 μm cavity length was mounted P-side down on a microchannel-cooled heatsink, and a peak PCE of 60% is obtained at 26.3-W continuous wave output power.The results prove that this novel asymmetric waveguide structure design is an efficient approach to improve the PCE.

Design of a Frequency Divider with Reduced Complexity Based on a Resonant Tunneling Diode

A novel edge-triggered D-flip-flop based on a resonant tunneling diode (RTD) is proposed and used to construct a binary frequency divider. The design is discussed in detail and the performance of the circuit is verified using SPICE. Relying on the nonlinear characteristics of RTD, we reduced the number of components used in our DFF circuit to only half of that required using conventional CMOS SCFL technology.

Gain Switch of an AlGaInP Red Light Semiconductor Laser Diode

We solve the single mode coupled rate equations by computer, simulate the behavior of a gain switch of an AlGalnP red light semiconductor laser diode, and find the characteristic of FWHM of pulses changing with the amplitude of modulation signal, the bias current, and the modulated frequency. On this basis, we conduct experiments. The experiment results accord with the simulations well.