15 February 2018 High-peak power fiber amplifier for deep-space laser communications
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Fiber amplifiers have been used in many laser communication applications due to their compactness and high efficiency. However, fiber amplifiers for free space laser communications have been limited to low peak power communication formats due to nonlinear effects such as Self Phase Modulation (SPM). At high peak powers, SPM can broaden the spectrum of free space laser communication signals to an unacceptable degree, moving much of the transmitted power outside the receiver’s designed bandwidth. The Laser Communication Relay Demonstration (LCRD) needed a fiber amplifier that could amplify a 3.5 GHz wide signal to peak powers of nearly a kilo-Watt with little to no spectral broadening due to SPM. We tested several different commercial amplifiers and found an Er-doped, Very Large Mode Area (VLMA) fiber amplifier, pumped by a 1480 nm Raman fiber laser, met the needs for both high peak power and minimal spectral broadening. The high peak power performance of the VLMA amplifier is enabled by the large effective area of ~ 1100 μm2 . We will present a detailed analysis of the effects of SPM on the amplified signal spectrum for both pulse position modulation (PPM) and differential phase shift keyed (DPSK) communication formats at peak powers up to 1 kW. Additionally, Bit Error Ratio (BER) performance data taken with the LCRD modem showed the signal did not suffer a measureable penalty from amplification with the VLMA amplifier. The ability to reach the required high peak power with this fiber amplifier makes it possible to consider its use for deep space laser communication, e.g. with high order M-ary PPM formats where such high peak powers are needed.
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Robert E. Lafon, Robert E. Lafon, Scott Merrit, Scott Merrit, Graham Allan, Graham Allan, Jeff Nicholson, Jeff Nicholson, Anand Hariharan, Anand Hariharan, Anthony DeSantolo, Anthony DeSantolo, Armand Green-Wade, Armand Green-Wade, } "High-peak power fiber amplifier for deep-space laser communications", Proc. SPIE 10524, Free-Space Laser Communication and Atmospheric Propagation XXX, 105241C (15 February 2018); doi: 10.1117/12.2290864; https://doi.org/10.1117/12.2290864

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