We link the output spectra of a Ti:sapphire and a Cr:forsterite femtosecond laser phase coherently to form a continuous frequency comb with a wavelength coverage of 0.57–1.45 μm at power levels of 1 nW to 40μW per frequency mode. To achieve this, the laser repetition rates and the carrier-envelope offset frequencies are phase locked to each other. The coherence time between the individual components of the two combs is 40 μs . The timing jitter between the lasers is 20 fs. The combined frequency comb is self-referenced for access to its overall offset frequency. We report the first demonstration to our knowledge of an extremely broadband and continuous, high-powered and phase-coherent frequency comb from two femtosecond lasers with different gain media.
© 2004 Optical Society of America
(120.3940) Instrumentation, measurement, and metrology : Metrology
(190.2620) Nonlinear optics : Harmonic generation and mixing
(320.7090) Ultrafast optics : Ultrafast lasers
(320.7160) Ultrafast optics : Ultrafast technology
Albrecht Bartels, Nathan R. Newbury, Isabell Thomann, Leo Hollberg, and Scott A. Diddams, "Broadband phase-coherent optical frequency synthesis with actively linked Ti:sapphire and Cr:forsterite femtosecond lasers," Opt. Lett. 29, 403-405 (2004)