Cavity Enhanced Reflection of a DBR for High Power Laser Applications

Distributed Bragg reflectors (DBRs) have been developed as an effective way for reflecting light in several applications. In this work, a cavity medium is introduced between the DBR and substrate to increase the reflection by stimulating the cavity modes. The DBR has been designed carefully based on the quarter-wavelength rule utilizing the transfer matrix method (TMM). The thickness, number of layers, and material composition have been optimized, and the surface reflectance of a DBR-coated substrate with and without a cavity layer is compared. Employing FDTD simulations, the optimal thickness of the cavity layer for the incident wavelength of the interest is obtained. The results show a significant enhancement in the reflection by introducing the cavity in the design.