Design,Fabrication And Application On Biological Detection Of The V-coupled Cavity Laser Based On GaAs/AlGaAs Material

In the modern society, high-fat, high-calorie and high-salt eating habits and sedentary life style contribute a lot to the increasing rate of cardiovascular and cerebrovascular diseases. Prevention, diagnosis and treatment of those diseases impose a heavy burden on both individuals and goverment. Early and accurate prediction and prevention is the most cost-effective solution to these problems. Tunable laser based on GaAs/AlGaAs material system, with its output wavelength corresponding to the life-detection optical band, excellent single longitudinal mode and wavelength tunable performance, ease of integration, can be used to monitor some important parameters in human blood regardless of place and time, which is a key components against those disease. This paper studied the structure design, fabrication, testing and blood parameters detection of the V-coupled-cavity laser based on GaAs/AlGaAs material system.We first introduced the basic structure and the working principle of the V-coupled cavity laser, derived the threshold condition of the laser. Designed a quantum well structure and the wafer layer structure for the V-coupled cavity laser based on GaAs/AlGaAs material system.Optimized the waveguide structure and the V cavity structure to obtain the maximum wavelength tuning range, optimized the size of the coupler to obtain the best performance of output side mode suppression ratio (SMSR).After that we described the fabrication processes of the V cavity laser based on GaAs/AlGaAs material system in detail. The step such as photolithography process, etching process for waveguide and deep etching aera, the planarization process, the front and back electrode, wafer backside thinning and polishing process are analyzed, in particular for the etching process, for which the choice of the mask, dry and wet etching process selection, dry etching recipe selection and optimization of a detailed analysis. Finally, we successfully fabricated the V-coupled cavity laser based on GaAs/AlGaAs material system.Then we described the laser performance tests, introduced the configuration and equipment constitutes of the test system. Through the FP laser testing, informed the IV/IP characteristics of GaAs/AlGaAs material based laser and the phenomenon of the catastrophic optical mirror destruction (COMD), analyzed the role of wet etching process on the COMD phenomenon. Introduced the tuning mechanism of the V cavity laser based on carrier injection effect and thermal effect. Under the carrier injection effect, the laser output SMSR is31dB, with the temperature control, the laser can be tuned27channels, the tuning range is8.2nm, under the thermal effect, the laser output SMSR is36dB, he laser can be tuned31channels on single stable temperature, with the temperature control,60channels tunable with tuning range of22.4nm is achieved.We proposed a reflective human blood detection system, introduced the principle to detect oxygen saturation and blood flow velocity, the V-cavity lasers is used in this system, and some results was obtained. Proposed a method to detect the concentration of blood glucose with frequency modulated continuous wave (FMCW) technology, builded a validation experiment testing system, some results was obtained and analyzed.Finally, we discussed the future research plans fot the laser design, fabrication and applications in biological detection.