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


Wunderer, T., Jeschke, J., Yang, Z., Teepe, M., Batres, M., Vancil, B., & Johnson, N. (2017). Resonator-length dependence of electron-beam-pumped UV-A GaN-based lasers. IEEE Photonics Technology Letters, 29(16), 1344-1347.


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.

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