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Title: Transverse mode control in high gain, millimeter bore, waveguide lasers

Abstract

A technique is presented for assuring TEM/sub 00/ transverse mode operation in visible wavelength lasers with bore diameters of 0.1 to 1.0 mm. This then is a solution to the problem of obtaining TEM/sub 00/ mode output from pulse pumped dye lasers which have high and non-uniform gain. The desired mode control is achieved by confining the lasing medium in a waveguide and placing each resonator mirror so that its focal plane, rather than its center of curvature, lies at the nearest waveguide opening. Thus, the far-field pattern of the field distribution emerging from the waveguide opening is focused by the mirror back into the waveguide. For the proper choice of mirror curvature, the width of the central lobe of the far-field pattern is such that over 99 percent of the energy couples into the two lowest order modes of the waveguide. Analysis of the resonator shows that a TEM/sub 00/ mode having a curved wavefront at the waveguide opening couples primarily to both the EH/sub 11/ and EH/sub 12/ waveguide modes. The amplitudes of the EH/sub 11/ and EH/sub 12/ modes, however, have a complex phase difference which results in a refocussing of the field distribution when both propagatemore » in a hollow waveguide. The refocusing is shown to be a periodic function of the length of the waveguide. In addition, it is shown that as a result of gain or propagation loss differences for the two waveguide modes, the phase radius of curvature of the TEM/sub 00/ mode of a waveguide resonator does not in general match the mirror curvatures. This model of TEM/sub 00/ mode coupling to the EH/sub 11/ plus EH/sub 12/ modes results in a clearer physical insight into the interaction between the waveguide and free space portions of the resonator.« less

Authors:
;
Publication Date:
Research Org.:
Univ. of Southern California, Los Angeles
OSTI Identifier:
5182210
Resource Type:
Journal Article
Journal Name:
IEEE J. Quant. Electron.; (United States)
Additional Journal Information:
Journal Volume: QE-13:10
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; CARBON DIOXIDE LASERS; MODE CONTROL; DYE LASERS; HELIUM-NEON LASERS; WAVEGUIDES; GAS LASERS; LASERS; 420300* - Engineering- Lasers- (-1989)

Citation Formats

Roullard, III, F P, and Bass, M. Transverse mode control in high gain, millimeter bore, waveguide lasers. United States: N. p., 1977. Web. doi:10.1109/JQE.1977.1069239.
Roullard, III, F P, & Bass, M. Transverse mode control in high gain, millimeter bore, waveguide lasers. United States. doi:10.1109/JQE.1977.1069239.
Roullard, III, F P, and Bass, M. Sat . "Transverse mode control in high gain, millimeter bore, waveguide lasers". United States. doi:10.1109/JQE.1977.1069239.
@article{osti_5182210,
title = {Transverse mode control in high gain, millimeter bore, waveguide lasers},
author = {Roullard, III, F P and Bass, M},
abstractNote = {A technique is presented for assuring TEM/sub 00/ transverse mode operation in visible wavelength lasers with bore diameters of 0.1 to 1.0 mm. This then is a solution to the problem of obtaining TEM/sub 00/ mode output from pulse pumped dye lasers which have high and non-uniform gain. The desired mode control is achieved by confining the lasing medium in a waveguide and placing each resonator mirror so that its focal plane, rather than its center of curvature, lies at the nearest waveguide opening. Thus, the far-field pattern of the field distribution emerging from the waveguide opening is focused by the mirror back into the waveguide. For the proper choice of mirror curvature, the width of the central lobe of the far-field pattern is such that over 99 percent of the energy couples into the two lowest order modes of the waveguide. Analysis of the resonator shows that a TEM/sub 00/ mode having a curved wavefront at the waveguide opening couples primarily to both the EH/sub 11/ and EH/sub 12/ waveguide modes. The amplitudes of the EH/sub 11/ and EH/sub 12/ modes, however, have a complex phase difference which results in a refocussing of the field distribution when both propagate in a hollow waveguide. The refocusing is shown to be a periodic function of the length of the waveguide. In addition, it is shown that as a result of gain or propagation loss differences for the two waveguide modes, the phase radius of curvature of the TEM/sub 00/ mode of a waveguide resonator does not in general match the mirror curvatures. This model of TEM/sub 00/ mode coupling to the EH/sub 11/ plus EH/sub 12/ modes results in a clearer physical insight into the interaction between the waveguide and free space portions of the resonator.},
doi = {10.1109/JQE.1977.1069239},
journal = {IEEE J. Quant. Electron.; (United States)},
number = ,
volume = QE-13:10,
place = {United States},
year = {1977},
month = {10}
}