Study On Performance Improvement Of 9×× High Power Semiconductor Laser

High power semiconductor laser is a kind of widely used optoelectronic devices,has advantages of small volume,long service life,cheap price.In mechanical processing,materials processing,weapons,and laser display,and other industries have a wide range of applications.The electro-optical conversion efficiency is the important measure of high power semiconductor laser performance good or bad.Lower threshold current,smaller loss and series resistance is one of the important measures to improve the efficiency of electro-optical conversion.General test when not directly measuring electro-optical conversion efficiency of the device,but is measured by laser power-current(P-I)curve,through its slope(i.e.,external differential quantum efficiency or slope efficiency)to qualitatively evaluate the quality of the semiconductor laser.In pursuit of larger power,semiconductor laser cavity length needs to be enough to make the photon in full within the cavity oscillation of gain,but the device along with the increase of the cavity length of impurities and defects also corresponding increase,affect the exterior differential quantum efficiency.Loss is divided into internal loss and the surface of the cavity loss,including loss including active zone free carrier absorption loss and overflow photon loss of the active region.In order to ensure the device performance,can design late extensional structure and process to reduce the loss of the device,the threshold current density and the series resistance.Which reduce the wastage of the device is to improve the method of differential quantum efficiency main.In order to optimize the above limit the output power factor,this paper proposes a large optical cavity wide asymmetric waveguide component gradient structure of semiconductor lasers:(1)the large optical cavity structure can effectively increase the lateral size spot,reduce the cavity surface optical power density,reduce loss of photons of end face and improve the disastrous cavity surface damage(COMD)threshold,due to increased after the waveguide layer thickness at the same time,the light field development,in the heterojunction interface between source area and limiting layer of light field density smaller,reducing the photon scattering,diffraction and impurity absorption at the interfaces of photon absorption loss.(2)asymmetric waveguide structure can inhibit the neglected maser,improve the far-field beam quality,at the same time as P type carrier optical absorption coefficient is N type 3 ~ 4 times that of the carrier,so the asymmetric waveguide can reduce the overlap of light field with heavily doped area,reduce loss of free carrier absorption of light and heat saturation effectively suppresses the device.P at the same time zone waveguide is the main source of series resistance,on the basis of the total thickness of the waveguide,decrease the P type waveguide thickness,increase the N type waveguide thickness will reduce the overall series resistance.(3)by optimizing the thickness of the waveguide layer of doping,reducing the thickness of the waveguide layer near the quantum well mixed,further reduce the free carrier absorption caused by heavy doping,the cavity surface at the same time be free carrier absorption,too,fell,improve device COMD resistance level.(4)to increase component gradient layers can optimize the heterojunction interface state,reduce the level of the resulting voltage loss and scattering,diffraction loss can be optimized at the same time the heterojunction interface quality,optimize the device performance.In waveguide layer and restrictions between 17 nm of doping elements to the gradient layer,the doping can reduce free carrier absorption,at the same time can prevent the spread of impurity influence on internal quantum effect,at the same time reduce the leakage current p-type restricted layer.Semiconductor laser single tube test results as follows: the slope efficiency is 0.64 W/A,40 A electric shed maximum output power can reach 21.06 W,spectral line width 0.4 nm,internal quantum efficiency is 92.59%,the loss of 1.14 cm-1.Later in the process of lateral deep trench structure,lateral through Comsol software simulation current limitations,found etching depth than deep trench structure of the epitaxial layer for improving the efficiency of the injection of current effect is remarkable.Long test with 4 mm cavity semiconductor laser threshold current density of the single tube can reach 78.95 A/cm2,the threshold current can be up to 0.3 A.30 A current into the output power can reach 16.8 W.