Design validation for ICESat-2 space-based laser transmitter

Abstract

Fibertek is under contract from NASA Goddard to build four space qualified laser transmitters for the ICESat-2 (Ice, Cloud, and Land Elevation Satellite) program, a second generation orbiting laser altimeter. Pertinent laser parameters driving the design included laser wall plug efficiency, laser reliability, a relatively narrow linewidth with wavelength tunability, high beam quality (M 2 <1.6), short pulsewidths (<1.5ns), and energy scalable from 250 µJ to 900µJ in predefined steps. The laser design employs fiber coupled 880nm diodes and end-pump Nd:YVO4 slabs as the gain medium in a master oscillator/power amplifier (MOPA) architecture with an LBO second harmonic generator (SHG). Following the SHG is a telescope that sets the final beam size and divergence requirements. The first laser built will be the Integration and Test Laser (ITL) used for qualification of the design. The ITL will set the baseline parameters for the flight laser builds. The ITL will also validate the design for the telescope and will be subjected to the full environmental testing required for a space hardened flight laser. Environmental testing includes vibration, thermal vacuum conditions, and electromagnetic interference (EMI).Our presentation will address the measured laser parameters from ITL as compared to the as designed laser.

Solid state multi-wavelength laser development for planetary science laser mass spectrometer

“…The PLASMA ETU packaging design is currently in progress and targeting to meet NASA designated TRL6 (technology readiness level) subsystem maturity. The TRL6 qualification process is a necessary step in qualifying an instrument for space, requiring demonstration of a prototype that meets the form, fit, and function of a flight design under relevant environmental conditions [14]. All laser components will be prepared according to the approved processes for flight builds.…”

Three-year aging of prototype flight laser at 10 kHz and 1 ns pulses with external frequency doubler for ICESat-2 mission

“…One of the most critical reliability item is the degradation of pulse energy through degradation of the second harmonic in the frequency doubler. It is speculated that one of the ICESat-1 mission laser lifetime limitation came from a limited lifetime of frequency doubler [6]. A couple of early laser prototype demo units for ICESAT-2 (also interchangeably called Engineering Design Units or EDUs in this presentation; these were similar in design to that of used in this study) delivered to NASA from the vendor (Fibertek Inc.) in 2011 for demonstration and short life-aging tests, showed a substantial degradation of 532 nm energy and power, while insignificant changes in 1064 nm laser sub-systems.…”

“…The conceptual design considerations for the laser can be found in [2]. The technological development and qualification of various aspects of the laser can be found in [3,4,5,6]. The optical design of the laser is a master oscillator/power amplifier (MOPA) that includes an actively Q-switched short-pulse oscillator, a pre-amplifier, and a dual-stage power amplifier.…”