A frequency comb spanning more than one octave has been achieved by injecting the second-harmonic generation (780 nm) of a mode-locked fiber laser (1.56 μm) into a photonic crystal fiber. We propose and realize a novel interferometric scheme for observing the carrier-envelope offset frequency of the frequency comb. Frequency noise has been observed on the measured carrier-envelope offset frequency, which has been confirmed to be generated in the photonic crystal fiber by comparing the measured beat frequencies between cw lasers and frequency combs before and after the photonic crystal fiber. The mode-locked fiber laser is considered to be an important candidate for the light source used in realizing a compact optical frequency measurement system including applications in the telecommunication bands.
© 2003 Optical Society of America
(140.3510) Lasers and laser optics : Lasers, fiber
(320.7110) Ultrafast optics : Ultrafast nonlinear optics
(320.7140) Ultrafast optics : Ultrafast processes in fibers
(320.7160) Ultrafast optics : Ultrafast technology
Feng-Lei Hong, Kaoru Minoshima, Atsushi Onae, Hajime Inaba, Hideyuki Takada, Akiko Hirai, Hirokazu Matsumoto, Toshiharu Sugiura, and Makoto Yoshida, "Broad-spectrum frequency comb generation and carrier-envelope offset frequency measurement by second-harmonic generation of a mode-locked fiber laser," Opt. Lett. 28, 1516-1518 (2003)