To expand the span of the optical frequency comb (OFC), we generated the second harmonics of an OFC at 1.55µm , using a multiperiod periodically poled lithium niobate (PPLN) crystal. A coupled-cavity OFC generator with an average output power of 0.2 mW was amplified and expanded with a fiber amplifier and a dispersion-flattened fiber. The fundamental OFC average power and span were 100 mW and 45 THz, respectively. The second-harmonic comb’s span was 3.2 THz; however, we tuned the center frequency over 30 THz by changing the poling period. We also demonstrated that the second-harmonic comb can be used for frequency-difference measurement.
© 1999 Optical Society of America
(120.3930) Instrumentation, measurement, and metrology : Metrological instrumentation
(190.0190) Nonlinear optics : Nonlinear optics
(190.2620) Nonlinear optics : Harmonic generation and mixing
(230.4320) Optical devices : Nonlinear optical devices
(300.6210) Spectroscopy : Spectroscopy, atomic
B. Widiyatmoko, K. Imai, M. Kourogi, and M. Ohtsu, "Second-harmonic generation of an optical frequency comb at 1.55 µm with periodically poled lithium niobate," Opt. Lett. 24, 315-317 (1999)