Catastrophic Optical-Damage in High-Power, Broad-Area Laser-Diodes
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1195-B01-01
Catastrophic Optical-Damage in High-Power, Broad-Area Laser-Diodes Aland K. Chin1, Rick K. Bertaska2, Martin A. Jaspan3, Allen M. Flusberg3, Steve D. Swartz3, Maciej T. Knapczyk3, Israel Smilanski3 and Jonah H. Jacob3 1
Aland Chin, LLC, 45 Manomet Rd, Sharon, MA USA 02067; New England Analytical, LLC, 1 Chestnut St., Suite 3A, Nashua, NH USA 03060; 3 Science Research Laboratory, Inc., 15 Ward St., Somerville, MA USA 021431 2
ABSTRACT A detailed description of the phenomenon of catastrophic optical-damage (COD) in short (380µm cavity-length), 12µm aperture, proton-bombarded, double-heterostructure laser-diodes with uncoated facets was first presented in 1974. In these devices, COD generally initiates at the facets due to high optical-power density and propagate along transverse-mode filaments. To achieve reliable operation at high optical-power, broad-area laser-diodes have evolved to long (several-millimeter cavity-length), wide-aperture (50-200µm), dielectric-defined, broadenedwaveguide, separate-confinement, double-heterostructure, quantum-well laser-diodes with coated, passivated facets. COD in these devices involve both transverse modes and ring-cavity modes. INTRODUCTION COD description For modern, high-power laser-diodes, the remaining failure-mode is reported to be catastrophic optical-damage (COD). A brief description of the COD phenomena is as follows [1, 2]. A local region of the laser diode, generally at the front facet, is heated by absorption of the laser light so that the material melts. Since heat is generated by absorption of the laser light, the molten region is substantially confined to the active layer of the laser cavity. The surface of the molten region is optically reflective. Lasing is sustained in the optical cavity defined by the surface of the molten region and the back facet. The molten region propagates towards the back facet as the material exposed to the laser light continues to melt whereas the material on the opposite side, no longer heated by laser light, solidifies. Propagation of the molten region continues until there is insufficient gain in the optical cavity to maintain a liquid state. COD refers to the track of melted-resolidified material which is highly non-radiative because it contains a high density of material defects. This track of defective material appears dark in any image that maps the minority-carrier lifetime, e.g. photoluminescence imaging, electroluminescence imaging, electron-beam induced-current. While COD of single-mode lasers involves only transverse modes, we recently discovered [3, 4] that COD of modern, broad-area, multi-mode laser-diodes involves both transverse modes and ring-cavity modes. The presence of the ring-cavity modes accounts for many of the unusual features of COD, some of which have been reported but not explained [5-8]. This report provides a description of COD formation and propagation, with and without ring cavity modes, in broad-area laser-diodes.
Device structures COD formation and propagation depends on the device struct
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