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Spectrally resolved optical frequency comb from a self- referenced 5 GHz femtosecond laser



Albrecht Bartels, Raphael Gebs, Matthew S. Kirchner, Scott A. Diddams


We report a mode-locked Ti:sapphire femtosecond laser with 5 GHz repetition rate and 1.15 W of average power. Spectral broadening of the 24 fs pulses in a microstructured fiber yields an octave-spanning spectrum and permits self-referencing and active stabilization of the emitted femtosecond laser frequency comb (FLFC). The individual elements of the 5 GHz FLFC are resolved with a high-resolution spectrometer based on a virtually imaged phased array (VIPA) spectral disperser. The two-dimensional distribution of the modes within the image plane of the spectrometer is recorded on a digital camera, and a pinhole can be used to isolate individual modes (2 microwatts power) from their neighbors with contrast greater than 20 dB. The expected spatial distribution of adjacent modes is verified by measuring their frequencies. The combination of the high-power, frequency-stabilized 5 GHz laser and the straightforward resolution of its many modes will benefit applications in direct frequency comb spectroscopy. Additionally, such a stabilized FLFC should serve as a useful tool for direct mode- by-mode Fourier synthesis of arbitrary optical waveforms.
Optics Letters


femtosecond laser, frequency comb, waveform generation


Bartels, A. , Gebs, R. , Kirchner, M. and Diddams, S. (2007), Spectrally resolved optical frequency comb from a self- referenced 5 GHz femtosecond laser, Optics Letters, [online], (Accessed July 15, 2024)


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Created September 1, 2007, Updated February 17, 2017