Command-shaping based on impulse response function for dynamic-mode control of internal and external cavities in external-cavity diode laser.

An external-cavity diode laser (ECDL) generally includes low-frequency tuning capability. As the tuning frequency increases, the mechanical vibration of the external-cavity inherent in the ECDL is enhanced, disrupting the mode-matching of the internal and external cavities and considerably reducing the mode-hop-free (MHF) tuning range. In order to implement a wide MHF range with high-frequency tuning, we present an active internal-cavity mode control method with an impulse response function (IRF) shaper for the dynamic mode-matching of the internal and external cavities. After introducing the IRF shaper, experimental results indicate significant improvement in the MHF range with high-frequency tuning. In addition, a maximum wavelength tuning rate of 7.56 THz/s is obtained using an uncoated laser diode with a central wavelength of 785 nm.