Tech Briefs

A High-Repetition-Rate Seeded Optical Fiber Amplifier (SOFiA) for the LIST Mission and Next-Generation Satellite Laser Ranging

A document describes a fiber/solid-state hybrid seeded regenerative amplifier capable of achieving high output energy with tunable pulse widths for satellite laser ranging (SLR) applications. The diode-pumped solid-state (DPSS) regenerative amplifier cavity utilizes a pair of Nd:YAG zigzag slabs oriented orthogonally to one another in order to circularize thermal lensing effects and simplify optical correction schemes. The short-pulsed seed laser is a fiber-coupled 1,064-nm narrow-band (<0.02 nm) diode laser that is intensity modulated by a fiber Mach-Zehnder electro-optic modulator, enabling continuously tunable seed pulse widths in the 0.2-to-2.0-ns range.

Even though discretely pulsed diode-seeded regenerative amplifiers have been periodically pursued and published for various applications, this is a relatively unique application in its installation of a photon-counting SLR installation. The dual-head gain module, high-brightness diode arrays, and a 1064- nm gain-switched, short-pulsed diode laser seeder make this system unique. Also, the integration of fiber-coupled, gain-switched diode seeds means that one can easily incorporate several pulse widths in a single SLR system by adding multiple seed lasers tuned to various pulse shapes. The operator can cycle between seed sources electronically with no realignment or changes in optical configuration. Effectively, this SOFiA laser design can produce > 60 dB of optical gain in a single stage amplifier, with temporal jitter around 40 ps shot-to-shot.

This work was done by Donald Coyle of Goddard Space Flight Center; Demetrios Poulios and Richard B. Kay of American University; and Gordon W. Blalock of Sigma Space Corporation. GSC-16361-1