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Complex External Optical Feedback Distributed Feedback Laser Self-mixing Interference Theory

Posted on:2009-02-11Degree:MasterType:Thesis
Country:ChinaCandidate:Y G ZhangFull Text:PDF
GTID:2208360245976879Subject:Physical Electronics
Abstract/Summary:PDF Full Text Request
When a portion of light emitted from a laser source is reflected or scattered back into the laser cavity by an external target, the reflected light will mix with the light inside the cavity, causing a modulation of the laser output power. This phenomenon is called as self-mixing interference. Compare with the conventional interference, self-mixing interference have similar phase sensitivity, modulation depth ratio, and the movement direction can be discriminated through the self-mixing interference signal. These factors reveal self-mixing interference for optical sensing applications have good prospect.Because of the effects of self-mixing interference, the spectrum linewidth of laser will be squeezed or unfolded. This phenomenon can be used in linewidth squeeze. In optical fiber communication, the linewidth will be affected by multiple factors. So, in this paper, we analyzed the self-mixing interference effect to linewidth in the LD with multiple external reflectors and multiple feedback.In the first, we analyzed the self-mixing interference in gain-coupled (GC) distributed-feedback (DFB) lasers. According to the thin film optics theory, the optical beam reflected by two facets of the film form thin film interference. Extending this theory, the self-mixing interference of multiple external cavities system can be predigested. According to the general expressions of the threshold gain, frequency and linewidth in the DFB lasers, we made some simulation analysis at different conditions. Secondly, the self-mixing interference effects with multiple optical feedbacks are researched. The theory of the self-mixing effect has been analyzed. This theory is useful to the study of double fringe frequency. At last, we analyzed the self-mixing interference in DBR semiconductor lasers. Under the condition of weak feedback, the theory of the self-mixing effect has been analyzed. According to the expressions of gain and frequency in compound laser cavity, we made some simulation analysis at different conditions.
Keywords/Search Tags:self-mixing, multiple external reflectors, linewidth, multiple feedback
PDF Full Text Request
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