| Summary: | 博士 === 國立中山大學 === 物理學系研究所 === 103 === This research investigated the feasibility of employing beam-profile-adapted optical feedback to conduct commercial multitransverse-mode vertical-cavity surface-emitting lasers (VCSELs) to emit a single transverse mode with a wide tuning range. The fundamental transverse mode could be conducted to lase with a tuning range of about 1285 GHz and side-mode suppression ratios (SMSRs) of around 20 dB.
Furthermore, this work presents a simple method using a linearly feedback mechanism. A stable fundamental-mode lasing was achieved within a tuning range as wide as 1000 GHz, or 2.6 nm, and SMSR around 20 dB. The beat note was not appeared for the laser’s current from 2 to 20 mA, and revealing a low-noise output.
Finally, a ring path or linear path controlled single-mode-fiber optical feedback, which were conducted to characterize the stable fundamental-mode operation of a donut-like multitransverse-mode Laguerre–Gaussian laser. All the single-mode-fiber cavities are prefer the circular symmetric beam-profile to other unsymmetrical VCSELs. The single-mode-fiber cavity can operate the more experiments of alternative current, orthogonal optical feedback, and temperature control in heat sink. Our laser systems are established a wide tuning of current and a low divergent angle single mode. These discoveries assist in the application of the semiconductor lasers.
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