Lifetime data is presented for ruggedized commercial NPRO lasers used in the Tropospheric Emission Spectrometer (TES) Instrument on NASA's Aura Earth-orbiting spacecraft, including 20 years of data from two life test units on the ground, 12 years of on-orbit data from TES Laser A, and 2 years of on-orbit data from TES Laser B. The TES lasers are diode-pumped Non-Planar Ring Oscillator (NPRO) lasers using Nd:YAG crystals. Since accelerated life testing was not possible on the complete laser, early prototype lasers that had gone through thermal cycling and vibration testing were placed on non-accelerated life tests with the hope of gathering at least a couple of years of data before launch. Long-term lifetime data for hybrid laser systems in space applications is not abundant, and out of necessity, accelerated reliability testing is usually done over a relatively short time with a large number of devices. The data presented in this paper is unique as it tracks the optical power output over time of a total of four lasers on the order of decades rather than months or years. Two of the lasers have each been on life test for over 20 years on the ground and are still operating, and the other two lasers have been on-orbit for 14 years. TES Laser A was still operating when the TES Instrument was decommissioned in January 2018. Therefore, the data presented covers over 450,000 non-accelerated device-hours, with 23% of those hours being in space.

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The success of interferometry in space depends on the development of lasers that can survive launch conditions and the challenging space environment during missions that could last five years or more. This paper describes the fabrication of a rugged, laser-welded package for a 200mW, monolithic diode-pumped solid-state Nd:YAG laser operating at 1319nm. Environmental testing shows that the laser withstands non-operational thermal cycles over a temperature range from -20ºC to 55ºC, and 22.3 g-rms of random vibration, with little or no degradation of laser output power or performance. The novel packaging method employs a specially designed housing to which multi-mode or single-mode polarization-maintaining fiber pigtails can be aligned and laser-welded into place. To further enhance reliability, a redundant pumping system called the Multi-Fiber Pump Ferrule (MFPF) was developed and implemented. The MFPF allows multiple laser diode pump modules to be aligned to the laser crystal simultaneously, in order to accommodate either parallel or standby pump redundancy. This compact, lightweight design is well suited for space flight applications and the laser-welded technique can easily be adapted to a number of other fiber optic and electro-optic devices in which critical optical alignments must be maintained in a harsh environment.