| 摘要 |
PCT No. PCT/GB89/00212 Sec. 371 Date Aug. 13, 1990 Sec. 102(e) Date Aug. 13, 1990 PCT Filed Mar. 1, 1989 PCT Pub. No. WO89/08340 PCT Pub. Date Sep. 8, 1989.A laser amplifier in which the effective refractive index of the active region for the TE and TM modes is sufficiently different to provide multiple mode ripple beat frequency overlap within a 3dB gain envelope peak. The active region is made highly asymmetric with an aspect ratio of at least 10:1 and preferably 20:1 in order to provide the effective refractive index difference. Steps, grading or uniform difference in the material refractive index may also be used. The confinement factor ratio is made as high as possible by providing different material refractive index in the orthogonal dimensions of the active region cross section.
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