Synchronous tuning method for external-cavity diode lasers without antireflection coating based on nonlinearity correction model for internal and external cavities

Abstract

Synchronous tuning can extend the mode-hop-free (MHF) tuning range of external-cavity diode lasers (ECDLs) without antireflection coating. However, due to nonlinearities in the internal and external cavities of ECDLs, the synchronous tuning ratio is not constant, causing detuning, which limits the MHF tuning range. To solve the nonlinearity mismatch between the two cavities, the nonlinearity of the internal cavity is identified and a correction model for the both cavities based on a mapping method is established. Further, the zero-vibration-derivative (ZVD) method is applied to optimize the dynamic response of the system. Experimental results show that MHF tuning in the full scanning period is achieved, and the optical frequency shows good linearity.