Dresden 2014 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 97: Semiconductor laser II: Microcavities and quantum-dot laser
HL 97.4: Talk
Thursday, April 3, 2014, 16:15–16:30, POT 051
Timing jitter reduction in a mode-locked laser subject to optical feedback — •Lina Jaurigue1, Christian Otto1,2, Eckehard Schöll1, and Kathy Lüdge1 — 1Institut f. Theo. Physik, Sekr. EW 7-1, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany — 2Potsdam Institute for Climate Impact Research, Telegrafenberg A26, 14412 Potsdam, Germany
Passively mode-locked (ML) lasers have a relatively large timing jitter due to the absence of an external reference clock. We investigate the effect of optical feedback (FB) on the timing stability of a passively ML laser. To model the ML laser we use a set of three coupled delay differential equations (DDE) describing a ring cavity, consisting of a gain section and a saturable absorber section. Optical FB is modeled by coupling the ring cavity to an external cavity. In the absence of FB the free running laser produces ultra-short pulses which have an internal cavity round trip time of TISI,0. When FB is added there is a second important time scale, the external cavity round-trip time τ. FB is resonant when p TISI,0 = qτ, where p and q are integers. Through resonant FB the timing jitter of the ML laser can be reduced and it has been shown that longer external cavities lead to a greater reduction in the timing jitter. This is, however, not always the case. For example, with non-zero α-factors (linewidth enhancement factors) resonant FB can give rise to destabilized pulse streams. For non-resonant FB the timing jitter is dramatically increased.