We prepare top-emitting 850 nm vertical-cavity surface-emitting laser (VCSEL) with a large oxide-aperture of 11 µm. The temperature-dependence of the output characteristics such as optical output power, threshold current, differential resistance and small-signal modulation bandwidth (f3dB) are investigated. At room temperature, the VCSEL achieves a maximum optical output power of 12.62 mA and a maximum f3dB of 18.5 GHz. With the increase of temperature, the thermal rollover current and the maximum optical output power both decrease. When the temperature rises to 55℃, the f3dB of the device remains above 18 GHz. Finally, the modulation current efficiency factor (MCEF) at different temperatures is extracted by linear fitting of the f3dB and the square root of the bias current above the threshold.
Beam steering devices are widely used in laser radar, optical communication, free space optical interconnection and other fields. But at present, most beam steering devices are large in size, complex in structure and low in reliability, and then integration, portability and low power consumption of beam steering devices are the urgent problems to be solved in modern photoelectric system. This paper introduces a two-dimensional beam steering chip that integrates the liquid crystal optical phased array on the in-phased coupled Vertical Cavity Surface Emitting Laser (VCSEL) array. The theoretical model of beam steering chip is used finite difference time domain method to set up and simulate. The beam steering chip can theoretically achieve two-dimensional beam steering, with a max deflection range of 4.96°.
Semiconductor lasers with good fundamental transverse mode stability have important applications in optical communications, light sources, biomedical and other fields. For Fabry-Perot (FP) lasers, lateral mode control is an important issue. In this paper, the influence of the side double-trench ridge waveguide structure of the semiconductor FP laser on the output mode characteristics is analyzed theoretically. The device is modeled and calculated using matlab software. FP laser with different ridge width and trench width are designed and fabricated using the double-trench ridge waveguide structure. The influence of the leakage loss of the double-trench waveguide structure on the mode output characteristics is analyzed.
A single layer of tightly arranged silicon oxide nanospheres was formed on GaAs substrate by gas-liquid interface self-assembly method. The silicon oxide nanospheres were used as the etching barrier layer, and the GaAs nanocolumn array was prepared by dry etching with Inductively Coupled Plasma (ICP) of SiCl4/Ar gas. The results show that the morphology of GaAs nanocolumns can be optimized by controlling the technological conditions in the preparation process, such as reaction gas flow, sample chamber pressure and RF power. The optimal technological parameters are obtained, and the GaAs nanocolumn arrays with smooth and steep sidewalls are prepared.
Vertical-cavity surface-emitting lasers (VCSELs) with single-mode, single-polarization emission at a wavelength of 894.6 nm was demonstrated for miniaturized atomic clocks. Utilizing the direct-etched surface grating on the surface of VCSELs, the state of polarization of VCSELs was controlled and pinned over the whole current range. The Modal properties of VCSELs with grating structures was studied using a finite difference time domain (FDTD) method. We investigate modal loss behavior with respect to the variation of grating structural parameters for the optimization of VCSELs polarization characteristics.
In this paper, the far-field characteristic of the vertical-cavity surface-emitting laser (VCSEL) incorporating a highcontrast subwavelength grating (HCG) is analyzed by finite-difference time-domain (FDTD) method. Full three-dimensional simulations are carried out by utilizing FDTD solutions software. We study the parameters of HCG made from GaAs/AlOx which is defined by wet oxidation of an Al0.98Ga0.02As spacer layer. We have simulated HCG-VCSELs with different HCG periods and oxide aperture diameters. Various far-field patterns including single-lobe, double-lobe, triple-lobe shapes are obtained with the designed HCG-VCSEL. More interestingly, by tuning the HCG periods and the oxide aperture diameter, the far-field emission patterns transform from double-lobe to single-lobe shapes. By proper design of the two parameters, one can obtain Gaussian-like beam outputs, double-lobe or multi-lobe beams. The fullwidth half-maximum (FWHM) of the far-field divergent angle of the Gaussian-like fundamental mode obtained with grating periods of 23 and oxide aperture diameter of 8 μm is less than 5 degree. This opens a new path for engineering a VCSEL’s emission properties and provides guideline for actual device fabrication.
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