Abstract
Far‐infrared radiation tunable between 93 and 100 cm−1 has been produced by difference frequency mixing between the 944.2‐cm−1 pump and the tunable frequency‐shifted Stokes radiation from an InSb spin flip Raman (SFR) laser. Mixing occurs in a separate crystal of InSb using the strong nonlinearity of the electron spins. Since operation of both SFR laser and mixer require the same geometry and magnetic field, they are mounted together in the superconducting magnet.