Research And Manufacture Of Broad-stripe Second-order Metal Grating Distributed Feedback Semiconductor Lasers

Recently, high power broad-stripe lasers are widely used in many fields, such asindustry, laser medicine, military, pump, information processing, optical frequencyconversion, phase array radar, and free-space optical communication, especially usedas pump sources for solid state lasers, fiber lasers and fiber amplifiers. Theseapplications require high power, small far field angles, narrow spectral linewidth,and stable lasing frequency, higher and higher. However, conventional broad-stripelasers have clearly deficiencies in their performance, such as multimode operation,large spectral linewidth (2~3nm), poor wavelength stability (0.2~0.3nm/K), highdivergence angle with differences in slow axis and fast axis, which badly limit manydirect applications of broad-stripe lasers. So, how to narrow spectrum linewidth,stabilize emission wavelength, reduce divergence angle, and improve beam qualityand spectral characteristics becomes an important problem urgent to be solved.In this paper, the second-order metal gratings are integrated into the cap layer orp-cladding layer of broad-stripe lasers, and based on the special diffraction effect andsurface plasma enhancement effect existing in the metal-semiconductor interface, thebroad-stripe second-order metal grating distributed feedback end-emittingsemiconductor lasers (DFB-LD) and surface-emitting lasers (SEDFB-LD) can befabricated to obtain high power, small far-field angles, narrow spectral linewidth, high wavelength stability and stable single mode operating output, so as to meet thedemand of many fields for lasers with high power and beam quality. The mainwork and innovative achievements of the thesis are as follows:The first one: the paper shows systematically the basic principles and thefundamental aspects of DFB-LD and broad-stripe second-order metal gratingDFB-LD and SEDFB-LD, and analyzes distributed feedback theory and diffractioneffect of second-order metal gratings, surface plasma enhancement effect and thereflection of p-side ohmic electrode.The second one: the paper shows systematically the main methods to fabricatemetal/semiconductor gratings, including electron beam lithography (EBL),holographic lithography, nano-imprint lithography, ion beam lithography (IBL) andother lithography technology, and dry etching and wet etching techniques.The third one: we optimized and adjusted the fabrication technology ofsemiconductor lasers, combining with the fabrication technology of holographicgratings, and had a trial on IQE wafer emitting at940nm. We fabricated surfacesecond-order metal grating DFB-LD emitting at940nm successfully for the firsttime. Under room temperature continuous-wave (CW) conditions without anytemperature-control device, the uncoated laser achieves high powers400mW/facet,small spectral linewidth0.5nm and lateral far-field angle2.7o at1.5A (CW), andoperate in a stable longitudinal mode with wavelength-shift only4.13nm/A (CW)，and the beam quality and spectral characteristics are improved greatly. In pulsedoperation, at2.28A, output power is above600mW/facet, with11%wallplugefficiency.The fourth one: we designed, optimized the wafer structure and device structureof broad-stripe second-order metal grating SEDFB-LD emitting at980nm, andfinally did the eptaxial grown.The last one: we explored a whole set of fabrication process for broad-stripesecond-order metal grating DFB-LD and SEDFB-LD, and fabricated broad-stripesecond-order metal grating DFB-LD and SEDFB-LD emitting at980nm for the first time.