Red Diode Lasers for Photodynamic Therapy

Present high-power red (630- 700 nm) diode lasers do not fully meet medical instrumentation marketbecause both power and lifetime are limited by catastrophic- optical-mirror-damage (COMD). Proposedmeans of overcoming this problem to provide a transparent, lattice- matched, semiconductor window lalaser cavity mirrors. This will be done by modifying the atomically ordered GA(1- x)ln(x)P used as tdisordered form in the passivation layer. Key to this is the claim that the disordered material canhigher than ordered material of the same composition. It is claimed that this can make the facet winwhile preserving their ability to decrease the facet surface-state density. Phase I will address thepassivation concept by fabricating cleaved-facet red diode lasers (lambda about 680-690 nm) and complimit with those using (a) uncoated facets and (b) conventional dielectric-coated facets. In Phase Iwafer-scale facet etching and passivation schemes which eliminate the risks of damaging the delicatebars; this will greatly increase laser yield and reduce production costs. Another innovation to be dreplacement of AL(x)Ga(1-x-y)in(x)P with AI(x)(Ga(1-x)As cladding layers to reduce bulk heating probthermal and electrical conductivity. They also plan to fabricate and fiber -couple one- dimensionaland to make them available to commercial users for evaluation. All of the above-mentioned improvemenapplied to shorter wavelength (about 630 nm) lasers by adding aluminum to the active and facet-passi