We study and demonstrate the nonlinear frequency conversion of broadband optical pulses from 1053 nm to 351 nm using sum-frequency generation with a narrowband pulse at 526.5 nm. The combination of angular dispersion and noncollinearity cancels out the wave-vector mismatch and its frequency derivative, yielding an order-of-magnitude increase in spectral acceptance compared to conventional tripling. This scheme can support the nonlinear frequency conversion of broadband spectrally incoherent nanosecond pulses generated by high-energy lasers and optical parametric amplifiers to mitigate laser−plasma instabilities occurring during interaction with a target. The experimental results obtained with KDP crystals are in excellent agreement with modeling, demonstrating the generation of spectrally incoherent pulses with a bandwidth larger than 10 THz at 351 nm.

We demonstrate and optimize a high-energy laser amplifier for broadband, spectrally incoherent pulses based on optical parametric amplification, reaching pulse energies close to 400 mJ in the near infrared.

Broadband frequency conversion of nanosecond spectrally incoherent pulses from 1053 nm to 351 nm is demonstrated in a novel sum-frequency-generation noncollinear angularly dispersed scheme, yielding spectrally incoherent pulses with bandwidth greater than 10 THz.