Catastrophic Optical Bulk Damage Research Articles

Failure mode characterizations of semiconductor lasers

Catastrophic optical mirror damage (COMD) and catastrophic optical bulk damage (COBD) are the main factors that affect the reliability of semiconductor lasers. In this paper, we characterize the COMD and COBD failure modes by examining the voltage changes at the current point where failure occurs, as well as by using the electroluminescent technique. Our study reveals that the voltage has an increase at the failure current point for COMD samples, in which failure occurs due to the damage to the facet mirrors; for COBD samples, in which failure occurs inside the laser cavity, the voltage exhibits a decrease and the amount of voltage decrease is roughly proportional to the size of the damaged area.

Catastrophic Optical Bulk Damage – A New Failure Mode in High-Power InGaAs-AlGaAs Strained Quantum Well Lasers

ABSTRACTHigh-power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well (QW) lasers with emission wavelengths of 910 − 980 nm are extensively used in various fiber lasers and amplifiers for both telecom and defense applications. In particular, underseas and satellite communication systems require stringent reliability from these lasers. Since these lasers predominantly fail by catastrophic and sudden degradation due to COD, it is crucial especially for space satellite applications to investigate reliability, failure modes, and degradation mechanisms of these lasers. Catastrophic optical mirror damage (COMD) was known to be the only failure mode until our group reported a new failure mode in MM and SM InGaAs-AlGaAs strained QW lasers in 2009 and 2016, respectively. Our group reported that bulk failure due to catastrophic optical bulk damage (COBD) has become the dominant failure mode of both SM and MM lasers. Since there have been limited reports on COBD compared to COMD, the intent of this paper is to introduce our studies on COBD that have spanned the last decade. We investigated reliability, failure modes, and degradation processes in SM and MM InGaAs-AlGaAs strained QW lasers by performing short-term step-stress tests and long-term accelerated life-tests as well as failure mode analyses using various nondestructive and destructive micro-analytical techniques including electron beam induced current (EBIC), time-resolved electroluminescence (EL), deep level transient spectroscopy (DLTS), focused ion beam (FIB), and high-resolution TEM. EBIC and EL techniques were employed to study dark line defects generated in degraded lasers stressed under different test conditions. Time-resolved EL techniques were employed to study initiation and progressions of dark spots and dark lines in real time as lasers were aged. DLTS techniques were employed to study electron traps in both pristine and degraded lasers. Lastly, FIB and high-resolution TEM were employed to prepare cross sectional and plan view TEM specimens to study DLD areas in post-aged lasers. We also report our current understanding on degradation mechanisms responsible for COBD in both SM and MM lasers.

Catastrophic Optical Bulk Damage in High-Power InGaAs-AlGaAs Strained Quantum Well Lasers

High-power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well lasers are critical components for terrestrial and space satellite communications systems. Thus, it is crucial to understand reliability, failure modes, and degradation mechanisms of these lasers for the high-reliability applications. However, a little has been reported on failure modes and degradation mechanisms of state-of-the-art SM and MM InGaAs-AlGaAs strained quantum well (QW) lasers. This study addresses the aforementioned issues by performing long-term life tests, failure mode analysis (FMA), and physics of failure (root causes) investigation. We performed long-term accelerated life tests on SM and MM InGaAs-AlGaAs strained QW lasers. Our life tests have accumulated over 25 000 test hours for SM lasers and over 35 000 test hours for MM lasers. FMA was performed on degraded lasers using electron-beam-induced current, electroluminescence, focused ion beam, and high-resolution TEM. All the SM failures showed catastrophic and sudden degradation and all of these failures were bulk failures. Our group previously reported that bulk failure or catastrophic optical bulk damage (COBD) is the dominant failure mode of MM InGaAs-AlGaAs strained QW lasers. To the best of our knowledge, we are the first group demonstrating that the dominant failure mode of both SM and MM InGaAs-AlGaAs strained QW lasers is bulk failure. Since degradation mechanisms responsible for COBD are still not well understood, we also employed other techniques for the physics of failure investigation including deep level transient spectroscopy, time-resolved electroluminescence, and time-resolved photoluminescence to investigate COBD processes in SM and MM lasers.

Catastrophic optical bulk damage in InP 7xx emitting quantum dot diode lasers

Catastrophic optical bulk damage occurs in broad-area MOCVD-grown InP/(Al)GaInP 7xx emitting quantum dot diode lasers operated at high power with single, high-current pulses of 5–20 A, in contrast with quantum well devices, which undergo catastrophic optical mirror damage at similar power densities at the facet. After damage the quantum dot devices show a reduction in the nearfield emission intensity across the width of the facet. Panchromatic cathodoluminescence of the active region shows a decrease in intensity and reveals dark, non-radiative spots which enlarge as pulse length increases. The areal density of the spots, also present in unprocessed material from similar structures, is of the order of 106 cm−2, five orders of magnitude lower than the dot populations at 1011 cm−2. Increasing pump current pulse length to 500 ns and beyond did not increase the dark spot size, which depended on the duration of the lasing action, but decreased the cathodoluminescence intensity of both the spots and background regions inside the emitter stripe, while reference regions outside the stripe remained unchanged. These features can be used to characterize improvements in structures and growth in order to improve the performance of InP based quantum dot structures at high powers.