Stable, High-quality, and Tunable Frequency Combs

Tunable Low-noise Simpler stabilization method than conventional alternatives

Multi-heterodyne spectroscopy Data harvesting Pattern recognition Optical arbitrary waveform generation Analog-to-digital conversion Optical time-domain multiplexing

This invention consists of a commercially available semiconductor optical amplifier in an external fiber ring cavity and a Mach-Zehnder intensity modulator driven at the desired pulse repetition rate and frequency comb spacing for the intended application, both acting as polarization discriminating devices. Further, the method involves the use of two couplers for laser output and injection input, with multiple polarization controllers and an optical isolator to ensure unidirectional operation. The inventorsΓÇÖ prototype, for example, incorporates a continuous wave (CW) narrow linewidth (~1 kHz) laser at 1550 nm as the injection seed source, and a variable optical attenuator for injected power control. The injected tone experiences a phase shift while interacting with the cavity. Signals are then rotated via polarization controller(s) to interfere with both outputs of a fiberized polarization beam splitter. A balanced photodetector takes the difference between the two signals to produce an error signal.

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