.980 Nm Diode-pumped Laser Structure Design

Semiconductor lasers that emit at a wavelength of 980nm are currently the subject of considerable interest because they are capable of high power emission and are promising candidate sources for pumping Er-doped fiber amplifiers (EDFA). This application requires high output, long life and stable fundamental transverse mode operation. The performance characteristics of 980nm semiconductor have investigated in various kinds structures in the world, many advances have achieved. But there are still several problems: 1) Enhance the output of laser. Now the output of 980nm semiconductor laser have reached 400-500mW, higher power output may cause catastrophic optical damage (COD) and multimode appearance, which shorten laser's life time and destroy the stabilization of the fundamental mode. 2) Prolong the life time. It is more important to 980nm semiconductor when they are applied to fiber amplifier under sea ground. 3) Enhance the laser-to-fiber coupling efficiency. Since the severe asymmetry of optical field and beam divergence degrade the coupling efficiency, the waveguide structure optimizing needed. In order to improve the performance characteristics of 980nm semiconductor laser, my work have done as following:· Select GalnAs/GalnAsP as strained quantum structure, GalnAsP as confinement layer, GalnP as cladding layer and GaAs as substrate. This Al -free 980nm pump laser have many merits, such as improved catastrophic optical damage (COD) level; no degradation due to oxidation of aluminium during fabrication process and laser operation, which is desirable characteristic for multi-step growth; lower electrical and thermal resistance with GalnP cladding; better carrier confinement with GalnAsP confinement layers; Selective chemical etching between GaAs and GalnP maks precisely control for fabrication of stripe geometry lasers.· Calculated the physical parameters of ternary and quaternary III - V compoundsby interpolation formulas based on curve fits or on a linear regression, such aslattice parameter, band gap, and refractive index.· Using luttinger-kohn Hamiltonian-based propagation-matrix method presentedby S.L.Chuang, calculated band structure of GaxIm1-xAs/GainAsP strainedquantum wells, which can be chose as an active layer of 980nm pump laser foroptical communication. The energy levels of electrons and holes inGaxIni-xAs/GaInAsP strained quantum wells and their dispersion relations arealso obtained.· Using effective refractive index method, calculated the propagation constant ofmulti-waveguide. Optical confinement factor and lateral transverse modes alsoestimated.· Have a well study in Gas Source Molecular Beam Epitaxy (GSMBE) equipmentand epitaxy theory.