Resonator-length dependence of electron-beam-pumped UV-A lasers

The dependence of resonator length on the threshold power and emission wavelength of electron-beam-pumped UV-A edge-type emitting lasers is demonstrated. The lowest pump power thresholds are achieved for 100-200 m long resonators where there is good overlap of the focused e-beam spot with the resonator cavity. For longer resonator lengths the focused circular e-beam spot excites only a segment of the resonator cavity, yet lasing is observed. Absorption of the e-beam generated photons in the un-pumped sections of the resonator results in increased absorption losses and, consequently, higher laser thresholds. In addition, a significant wavelength shift from 375 nm for the 50 m resonators to 385 nm for the 600 m resonators is observed due to absorption of the higher energy photons and re-emission at longer wavelengths in the un-pumped sections.

Citation

Wunderer, T.; Jeschke, J.; Yang, Z.; Batres, M.; Teepe, M. R.; Vancil, B.; Johnson, N. M. Resonator-length dependence of electron-beam-pumped UV-A lasers.