Raman shifting a tunable ArF laser to wavelengths of 190–240 nm

Tunable radiation at far-ultraviolet wavelengths is produced by Raman shifting a modified (285 mJ at 1–100 Hz repetition rate) ArF excimer laser. Multiple Stokes outputs are observed in H2(20%), CH4(22%), D2(53%), N2(21%), SF6(2.1%), and CF4(0.35%). Numbers in parentheses are the first vibrational Stokes energy conversion efficiencies. We can access 70% of the frequency range 42 000–52 000 cm−1 (190–240 nm), with Stokes pulse energies that vary from 0.2 μJ to 58 mJ inside the Raman cell. One of our better results, using 110 mJ of pump energy and D2, is an energy conversion efficiency of 53% and a tunable Stokes energy that varies over the range 29–58 mJ/pulse for the wavelength range 204–206 nm.