Fabrication And Key Properties Study Of 1.3?m Band Superluminescent Diodes

Superluminescent diodes(SLDs)are kinds of semiconductor light sources with luminescence characteristics between lasers and light emitting diodes.SLDs are attractive for fiber-optic gyroscopes,optical time-domain reflectometers and optical coherence tomography systems due to their high output power,wide spectrum and weak temporal coherence characteristics.In recent years,the rapid development of high-precision sensing systems has placed higher demands on the high-power and wide-spectrum characteristics of SLDs emitting at 1.3?m band.Effective suppression of light oscillation plays a crucial role to achieve such characteristics,which is achieved by the waveguide structure and mainly affected by the waveguide's geometric parameters such as its corresponding width,length and tilted angle.Therefore,the systematic analyze of the influence of waveguide with different geometric parameters on the SLDs' performance makes great sense to further improve SLD's emitting output power and spectral width.Based on active region of InP-based multiple quantum wells and GaAs-based quantum dots,this thesis systematically analyze the influence of J-shaped waveguide with different parameters on the SLD's performance and improve the SLD's fabrication process in our lab to achieve the fabrication of high-power and wide-width SLDs.The main work and achievements are listed as follows:1.Based on the optical waveguide theory,the key geometric parameters of J-shaped waveguide which has great influence on SLD's performance has been limited:waveguide width of lO?m and 20?m,length of 2mm and 3mm and tilted angle of 6°,8° and 10°.To achieve the fabrication of high-power and wide-width SLDs,the effects of different waveguide parameters on the performance of SLDs have been analyzed and appropriate waveguide parameter combinations were selected for different epitaxial wafers(GaAs-based SLDs:10?m width,2mm cavity length,60°tilted angle;InP-based SLDs:10?m width,2mm cavity length,100°tilted angle).2.The fabrication process of SLDs' metal electrode has been improved.(1)We have simplified the electrode stripping process by reducing p-side electrode thickness from 400nm to 300nm.(2)Au/Ge/Ni and Ti/Pt/Au are adopted as n-type and p-type electrode materials.To reduce SLDs' contact resistance,thermal annealing temperature of 460 ?is adopted for electrode on GaAs wafer and its annealing time is 50s,while thermal annealing temperature of 350? is adopted for electrode on InP wafer and its annealing time is 60s.3.InGaAsP/InP multiple quantum wells(MQWs)superluminescent diodes are successfully fabricated by utilizing J-shaped ridge waveguide structure.For SLDs without anti-reflection coatings on the facets,when the cavity length of 2 mm,waveguide width of 10?m and tilted angle of 10°are adopted,the spectral full width at half maximum(FWHM)value of 27.1 nnm(centered at 1.34?m)and the output power of 37.6mW are simultaneously obtained under room temperature at 650mA continuous wave inj ection.4.InAs/GaAs quantum dots(QDs)superluminescent diodes are also successfully fabricated by utilizing J-shaped ridge waveguide structure.When the cavity length of 2mm,waveguide width of 10?m and tilted angle of 10° are adopted,the spectral full width at half maximum(FWHM)value of 28 nm(centered at 1.3?m)and the output power of 28.9mW are simultaneously obtained under room temperature at 600mA continuous wave injection.