Dual optical frequency combs generation with frequency-shifted feedback laser, method, and applications

Generation of dual-combs in frequency shifted feedback laser seeded only with optical amplifier spontaneous emission and containing single frequency shifting loop with single acousto-optic tunable filter as the frequency shifter is demonstrated. It is also shown that it is possible to obtain a pair of dual-combs simultaneously and to implement further down-conversion achieving the frequency spacing between the spectral components of the resulting optical comb equal to the frequency difference of these dual-combs and amounting to several tens of kHz. The OFC with 40 kHz frequency spacing containing more than 5000 spectral lines was observed. It is demonstrated that the generated dual-combs may be applied for optical materials refraction coefficient measurements.