Optical Parametric Amplifier
Amplifies picoJoule laser diode pulses to the milliJoule level (10^9 gain)
An OPA system was designed to pulse amplify the output pulses from the Intensus-DFB fiber laser system. The OPA has the capability of amplifying the injected idler (signal) pulse (C or L band) as well as generating the corresponding signal (idler) depending on the configuration and end usage. For example, injecting the idler at 1600 nm, generates a signal at 800 nm, with 532 nm pumping. With 1064 nm pumping and the injection of a 1600 nm signal, 3.2 microns is generated as the idler. Advantages that the OPA technology provides:
- Generate high energy, short pulses in the eyesafe and mid-IR regions
- High peak powers without deleterious non-linear effects as seen in fiber amplifiers
- Preservation of the seed signal spectrum
- Extremely low jitter of the amplified pulses (on the order of the system clock)
- Capability of sum-frequency mixing to DUV and VUV regions
The 1599nm seed light is derived from a temperature stabilized DFB laser diode, which is pulse-modulated with a fast 2-ns current pulse. The energy of this pulsed diode is in the picojoule regime; it is amplified by two stages of fiber amplification to the microjoule level. In order to scale the pulse further to the millijoule regime, a two-stage optical parametric amplifier (OPA) is used. This is a crystalline device that receives the microjoule pulses from the fiber amplifier, and through a process driven by a high energy pulsed Nd:YAG laser, the OPA boosts the 1599-nm pulse energy to tens of millijoules. The advantages of this approach are a highly stable wavelength, a low temporal jitter of the resulting amplified pulse, and the preservation of the short pulse duration originally generated by the diode.
Temporal Jitter: approximately 100 ps
The OPA pulse jitter (yellow trace) is shown below.