NASA's requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

NASA’s mission requirements for spaceborne laser diode arrays lead to a set of tests peculiar to space flight. The goal of these tests is to determine if vibration, radiation, or vacuum will impair the operation or lifetime of nominally 100W quasicontinuous wave 808nm laser diode arrays. To simulate the stresses expected during a mission, terrestrial tests involve mechanical vibration, simulating the acceleration of launch, exposure to the equivalent doses of ionizing radiation, and operation in a vacuum. Three sets of devices were tested: one set with random vibration up to 20 g root-mean-square (grms) applied along three axes, a second set of devices was irradiated with γ radiation (1.17 and 1.33MeV) at 744rad(Si)∕min up to 200krad(Si), and the third set was exposed to a flux of 5×1011 or 1012p∕cm2 of 200MeV protons up to 60krad total dose. Only the proton irradiated devices showed any effect attributable to the test: a slight rise in lasing threshold, which recovered over time with self-annealing. A selection of the devices were then operated in vacuum for a further 1400h accumulating 500×106 pulses without any signs of degradation. Similar results were obtained in a parallel test, conducted in air, accumulating over 109 pulses on a selection of the remaining devices.

No abstract

No abstract

In the recent past, NASA's space-borne laser missions have been dominated by low repetition rate (<100Hz), Qswitched Nd:YAG lasers pumped by quasi-continuous wave (QCW) 808 nm laser diode arrays (LDA). QCW LDA reliability data is limited and their mechanisms of failure is poorly understood. Our group has been working in gathering statistically significant data on these devices and have developed testing strategies to achieve mission success in a costeffective manner. In this paper, we present our approach for qualifying the LDAs for the Lunar Orbiter Laser Altimeter (LOLA) instrument scheduled to launch aboard the Lunar Reconnaissance Orbiter (LRO) mission. We describe our strategy to mitigate risk due to LDA failure given cost and schedule constraints. The results from extended testing of multiple LDAs in air and in vacuum are also presented.