Title :
Transverse mode structure and output stability of the p-Ge terahertz laser
Author :
Hovenier, J. Niels ; Orlova, Ekaterina E. ; Klaassen, Tjeerd O. ; Wenckebach, W. Tom
Author_Institution :
Dept. of Appl. Phys., Delft Univ. of Technol., Netherlands
fDate :
4/1/2002 12:00:00 AM
Abstract :
The p-Ge terahertz laser with flat external cavity mirrors exhibits intensity modulations at well-defined nonequidistant frequencies in the 8-80-MHz range, resulting from beating of transverse modes. A theoretical description of the mode structure of this cavity is given. Results compare well with experimental data on beat frequencies and far-field beam profiles obtained using a metal mesh out-coupling window. Based on calculations, a cavity with a reduced size back mirror is proposed to suppress higher order transverse modes. Experiments prove that a reduction of the mirror to about 70% of the end-face surface leads to an effective suppression of the intensity modulations. Such a cavity exhibits a strongly improved pulse-to-pulse stability of the output and a much better shape of the micro pulse train under mode-locked operation
Keywords :
elemental semiconductors; gallium; germanium; intensity modulation; laser cavity resonators; laser mirrors; laser mode locking; laser modes; laser stability; laser theory; optical pulse shaping; semiconductor lasers; submillimetre wave lasers; 8 to 80 MHz; Ga-doped Ge laser crystal; Ge:Ga; beat frequencies; end-face surface; far-field beam profiles; flat external cavity mirrors; higher order transverse modes; intensity modulations; metal mesh out-coupling window; micro pulse train shape; mode-locked operation; nonequidistant frequencies; output stability; p-Ge terahertz laser; pulse-to-pulse stability; reduced size back mirror; transverse mode beating; transverse mode structure; Frequency; Intensity modulation; Laser beams; Laser mode locking; Laser modes; Laser stability; Laser theory; Mirrors; Pulse shaping methods; Shape;
Journal_Title :
Quantum Electronics, IEEE Journal of
