No abstract

We demonstrate a new, to the best of our knowledge, method of generating mid-infrared pulses by difference frequency mixing the Stokes pulse generated by four-wave mixing in a photonic crystal fiber with the remaining pump pulse. The Stokes pulses generated by four-wave mixing are inherently overlapped temporally and spatially with the pump pulse at the output of the fiber. Focusing this output into a nonlinear crystal phase matched for difference frequency generation between the pump and Stokes pulses results in a simple method of generating mid-infrared pulses. With a pump source at 1.064 µm, and a photonic crystal fiber engineered to generate Stokes pulses at approximately 1.65 µm, we generate 160 mW of mid-infrared light at approximately 3 µm through difference frequency generation.

We report a seeded optical parametric generator (OPG) producing tunable radiation from 4.2-4.6 µm. The seeded OPG employs a 13 mm long CdSiP 2 (CSP) crystal cut for non-critical phasematching, pumped by a nanosecond pulsed, MHz repetition rate Raman fiber amplifier system at 1.24 µm. A filtered, continuouswave fiber supercontinuum source at 1.72 µm is used as the seed. The source generates up to 0.25 W of MIR idler power with a total pump conversion of 42% (combined signal and idler).

Anita Chandran reviews Power Failure: the Rise and Fall of General Electric by William D Cohan.

Having spent more than 40 years working in optical communications, Michael Robertson is one of the world’s longest-serving experts in the field of fibre-optics. To mark his retirement, he talks to Anita Chandran about cross-disciplinary research, the breakthroughs he made and the good and bad sides of fibre optics in the UK.