DBR‐free Optically Pumped Semiconductor Disk Lasers

Summary

This chapter discusses a new alternative that does away with distributed Bragg reflector (DBR) altogether. Departing from the traditional vertical external‐cavity surface‐emitting laser design, optically pumped semiconductor disk lasers without DBRs are investigated. Due to the high thermal resistance and optical losses of the growth substrates, the fabrication of DBR‐free semiconductor disk lasers typically requires substrate transfer and adhesive‐free bonding. In the DBR‐free transmission geometry, to date, continuous‐wave (CW) laser operation has been demonstrated with sapphire, silicon carbide, and single‐crystalline diamond substrates. The highest thermal conductivity heatspreader – single‐crystalline diamond – is only available in relatively small pieces, requiring separate processing and bonding of every laser chip. Silicon carbide is available in relatively large wafers with excellent surface quality and, despite the smaller thermal conductivity, has produced the highest CW output powers reported to date.