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Proceedings Paper

Pump modulated suppression of self pulsing in a pulsed fibre amplifier
Author(s): I. Khan; B. Srinivasan; A. Prabhakar
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Paper Abstract

We present an experimental study on the suppression of self pulsing in a single stage pulsed master oscillator power amplifier (MOPA), using pump modulation. Many applications require pulsed lasers operating at low repetition rate. Leaving the pump on for long duration without a seed pulse leads to accumulation of amplified spontaneous emission (ASE) and generation of a self-pulse that can damage the laser. For this experiment, the amplifier was fed with peak seed power of 500 mW having a pulse width and repetition rate of 100 ns and 10 kHz respectively. To study the effect of pump modulation on self-pulsing, we carried out the experiment with both a continuous pump and with a pulsed pump. The output was characterized using a constant fractional discriminator (CFD) that generated TTL pulses, in turn fed to a frequency counter. In case of a continuous pump of 2.4 W, with a low repetition rate of 10 kHz for the seed, we noticed self-pulsing of the MOPA. We obtained a maximum amplified signal output peak power of 162 W, or a pulse energy of 7.91 μJ. A further increase in pump power could lead to permanent damage to the system. In case of pulsed pump, the generated pump pulses were synchronized with the seed laser and had a 50 % duty cycle. The resulting output was again characterized with a CFD and counter. We were able to increase the pump power to 6.5 W with an output peak power of 160 W and pulse energy of 9.37 μJ without any sign of self-pulsing. Thus, using a simple method of pump modulation, we were able to reduce the accumulation of ASE and suppressed the phenomenon of self-pulsing at low repetition rates of the seed laser.

Paper Details

Date Published: 17 May 2018
PDF: 6 pages
Proc. SPIE 10683, Fiber Lasers and Glass Photonics: Materials through Applications, 1068339 (17 May 2018); doi: 10.1117/12.2307474
Show Author Affiliations
I. Khan, Indian Institute of Technology Madras (India)
B. Srinivasan, Indian Institute of Technology Madras (India)
A. Prabhakar, Indian Institute of Technology Madras (India)

Published in SPIE Proceedings Vol. 10683:
Fiber Lasers and Glass Photonics: Materials through Applications
Stefano Taccheo; Jacob I. Mackenzie; Maurizio Ferrari, Editor(s)

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