PCF Based High Reliability Arbitrary Pulse Pattern Laser Amplifier

A very diverse set of applications from lasers for accelerator applications to defense, to industrial to scientific and biomedical applications need to achieve pulsed laser beams that have both high energy per pulse and high average power.In current lasers systems only one or the other is achievable.As with networking equipment, the search is on for a “Software Defined Laser”, where a nearly arbitrary pulse patter can be cleanly and smoothly amplified to the kW level.Such a device would be very useful in a wide variety of Lidar applications where for both coherent and incoherent scenarios arbitrary pulse pattern generation that is easy to change and implement is very important and useful.In many cases the overall laser dynamics can be high impacted by the pulsing regime so understanding the relationship between the pulse format and the gain dynamics is crucial and the ability to tailor these dynamics to the input pulse profile and the pumping profile is very important The work being done at the Fermi National Laboratory by David Johnson and his co-workers is really one of the main centers of research on laser-based H- beam control applications and Optical Engines has a 7 year collaboration with FNL, providing PCF based pulse amplifiers that in their system have provided over 30% higher beam luminosity over previous methods.During the Phase 1 program OEI has met several times with FNL staff to fully understand the H- applications including pulsing formats and power requirements.These applications include notching, and momentum collimation.To meet these requirements, OEI has also developed and demonstrated a novel dual pass amplifier arbitrary seed source and has demonstrated operation at a wide array of pulse formats.This new design achieves an over 80% reduction in the number of components used in past systems which is the leading method for increasing the overall reliability of the system.In addition, OEI has amplified this output in a PCF based amplifier system to demonstrate the pulse leveling capabilities of this system.During the program OEI has worked with FNL to develop a transmitter-based system that would work with all the major H- beam control and diagnostics system.This design is modular such that the multiple applications can be addressed through a single product, and provide a robust means of going beyond the FNL applications to beam control and diagnostics applications around the world.The single transmitter has the arbitrary modulated seed source, key mid stage fiber amplifiers and a power fiber amplifier stage.Fiber amplifiers are much preferred to bulk Diode Pumped Solid State (DPSS) lasers for their high average power capability without having to cryogenically cool the DPSS system.While the average power during the 50us pulse is quite high the overall average power is low due to the 15Hz repetition rate of the particle beam.This allows for very high-density packaging of the laser diode pumps as for this application the diodes need to be heated to allow them to wavelength lock.Depending on the cost targets, average powers during the pulse can be from 2kW to 6kW.These transmitters (or a common transmitter and multiple amplifiers) can be ganged together to create the 20kW necessary for the momentum collimation application.Scientific, Industrial and Biomedical applications will benefit greatly by having access to the devices being developed here allowing software defined lasers to move into more parts of our lives.