Fiber MOPA Pulsed Pump Timing for Constant Output Energy

The pump source is configured to operate in pulsed mode rather than continuous wave mode. The pump pulses are synchronized with the signal pulse repetition rate, creating a periodic pumping action that matches the signal pulse train. This periodic pumping ensures that the gain medium is refreshed at the same rate as the signal pulses arrive, maintaining constant gain and constant output energy regardless of changes in the pulse repetition interval. The harmful amplified spontaneous emission is reduced because the pump energy is delivered in discrete pulses rather than continuously, limiting the time window for ASE accumulation.

The pump source operates periodically with pulses synchronized to the signal pulse train. When the pulse repetition interval is varied to adapt to different survey conditions, the pump source automatically adjusts its pulse timing to remain synchronized with the signal pulses. This maintains the periodic refresh of the gain medium at the correct rate, ensuring constant gain and constant output energy even as the pulse repetition interval changes. The adaptability of the pulse repetition interval is preserved while the output energy constancy is maintained through the synchronized periodic pumping action.

Instead of continuously increasing pump energy to compensate for gain depletion, the system uses periodic pump pulses that are synchronized with the signal pulse train. Each pump pulse delivers the necessary energy to refresh the gain medium just in time for the next signal pulse arrival. This periodic delivery of pump energy maintains constant gain and constant output pulse energy without the need for continuous high pump power. The synchronized timing ensures that pump energy is delivered efficiently only when needed, minimizing the total pump energy required and reducing amplified spontaneous emission compared to continuous wave pumping.