Font Size: a A A

Designs And Fabrications Of The 720 Nm Band V-coupled Cavity Laser For Biomedical Detection And The Perovskite Laser

Posted on:2018-06-27Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y F FengFull Text:PDF
GTID:1318330542951802Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
With the rapid development of times,human beings are increasingly concerned about health care.With the increasingly advanced level of science and technology,people's health concept has begun to gradually shift from passive treatment to active monitoring and prevention.The rapid development of intelligent wearable medical technology greatly cater to people's daily medical and health testing needs,making physical signs test more convenient and quick.In the field of biomedical sensing,semiconductor play a vital role due to their superior performance,small size,low cost and easy integration.However,little research has been done about the visible tunable laser in the field of biomedical sensing.Therefore,in this paper,we propose a single-laser-based sensing method for measuring both blood oxygenation and blood flow and we experimentally demonstrate the proposed method by using the laser we fabricated successfully.At the last part of the paper,we design an optically pumped edge-emitting perovskite distributed feedback(DFB)laser,and optimize the corresponding fabrication process.Firstly,based on Beer-Lambert's law and photon diffusion equation,we introduced the principle to detect oxygen saturation and obtained the expression of oxygen saturation SpO2.Then,we proposed and demonstrated a single-laser-based sensing method for measuring both blood oxygenation and blood flow.When the laser has a wavelength tuning range of 14nm and the initial wavelength of the laser is between 700 nm to 720 nm,the single-laser-based method is feasible.Based on the Doppler effect,the laser can also be used to measure blood flow.Then we designed a 720-nm-band widely tunable V-cavity laser(VCL)based on AlGaAs multiple quantum well.The structure of the quantum well is Al0.18GGa0.82As/Al0.45Ga0.55 with a well width of 4nm.After describing the operation principle of the VCL,we designed and optimized the structure of the VCL,including the waveguide and half-wave coupler.After that we decribed the fabrication process of the VCL in detail.The process steps such as photolithography process,etching process,planarization process,electrode proces and wafer backside thinning and polishing process are analyzed and optimized.Finally,we successfully fabricated the VCL.Then we performed a series of performance tests on the VCLs and FP lasers,such as the IV and IP characteristics.We introduced the tuning mechansm of the VCL based on carrier injection effect and thermal effect.Under the thermal effect,the VCL can be tunned 42 channels and the tuning range is 14.1 nm,which meets the requirement of the proposed single-laser-based method.We developed an emission-detection system of the reflective oximeter and fowmeter by employing the fabricated VCL.After calibrating the proposed system,we performed a breath holding experiment to test the system.We measured the SpO2 of a subject who holds the breath and the measuring result has an accuracy of 3.3%.Additionally,by occluding the upper arm with a pressurized cuff,we measured the blood flow of the finger.The measuring result from the VCL system agrees well with the commercial LDF,which confirms that the blood flow has been successfully measured by the proposed system.In the last part of the thesis,the current research status of perovskites are outlined.Then,we designed an optically pumped distributed feedback laser with perovskite active media and optimized the corresponding fabrication process.
Keywords/Search Tags:oxygen saturation, blood flow, quantum well, tunable lasers, wavelet transform, perovskite
PDF Full Text Request
Related items