Abstract
Chromatic dispersion control plays an underlying role in optoelectronics and spectroscopy owing to its enhancement to nonlinear interactions by reducing the phase mismatching. This is particularly important to optical frequency combs based on quantum cascade lasers which require negligible dispersions for efficient mode locking of the dispersed modes into equally spaced comb modes. Here, we demonstrated a dispersion compensated mid-IR quantum cascade laser frequency comb with high power output at room temperature. A low-loss dispersive mirror has been engineered to compensate the device’s dispersion residue for frequency comb generation. Narrow intermode beating linewidths of 40 Hz in the comb-working currents were identified with a high power output of 460 mW and a broad spectral coverage of 80 cm-1. This dispersion compensation technique will enable fast spectroscopy and high-resolution metrology based on QCL combs with controlled dispersion and suppressed noise.
Highlights
Chromatic dispersion is a naturally phenomenon that the velocity of light travelling in an optical medium changes with the light frequency.[1]
For frequency combs based on mode-locked lasers,[8] the dispersion introduced by the gain medium and other optical components in the laser resonator is always not desirable, because it tends to broaden and chirp the generated pulses, and destroys the spacing uniformity of the cavity modes
Frequency combs were demonstrated when Quantum cascade laser (QCL) were engineered with a broadband gain and a low dispersion so that the dispersed Fabry–Perot (FP) cavity modes were able to be locked into evenly spaced comb modes via four wave mixing.[12,14]
Summary
Chromatic dispersion is a naturally phenomenon that the velocity of light travelling in an optical medium changes with the light frequency.[1]. Dispersion compensated mid-infrared quantum cascade laser frequency comb with high power output
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