A monolithic optical frequency comb generator

A monolithic optical frequency comb (OFC) generator was realized by coating high reflection films on the facets of a LiNbO
₃
crystal used for an electro-optic (EO) phase modulator. The optical round-trip loss in the monolithic OFC generator was reduced to extend the span of an OFC. It is confirmed that the envelope of the OFC extended to a span as wide as 48 nm (or 6.1 THz) around 1.5 μm. The maximum measurable frequency difference, which was defined as the sideband frequency with the signal-to-noise ratio of 0 dB, was estimated to be also 6.1 THz.