1results about How to "Reduce line width" patented technology

The disclosure provides an external cavity quantum cascade laser testing device and method, the device comprising: an external cavity quantum cascade laser, comprising: a gain chip for generating a first light beam; a diffraction grating for diffracting the first light beam to obtain a first diffracted light beam and a second diffracted light beam, the first diffracted light beam propagating to the gain chip along a second direction for increasing the resonance strength of the gain chip; an infrared spectrometer for testing the second diffracted light beam to obtain a test result; wherein the side of the gain chip away from the diffraction grating is a back cavity surface, the side of the gain chip close to the diffraction grating is a front cavity surface, the back cavity surface and the front cavity surface have a first electric field, the back cavity surface and the diffraction grating have a second electric field, and the relative electric field strength of the second electric field relative to the first electric field is at a maximum value. The disclosure determines the optimal length of the external cavity in the device through the relationship between the relative electric field strength and the distance between the back cavity surface and the diffraction grating, and significantly reduces the output laser linewidth.