Transient response of wavelength switching in multicavity mode-locked laser diodes

Abstract

We report the transient response of wavelength switching in multicavity laser diodes. Spatially separated Bragg gratings embedded in a single fiber are used to map optical emission wavelength to photon round-trip time in an external cavity mode-locked laser diode. Transient emission wavelength and mode-locked pulse formation are explored by switching applied radio frequency modulation. Initial conditions are found to dominate transient response. A hot photon cavity has a characteristic rise time corresponding to approximately two photon cavity round trips. A cold photon cavity exhibits significant turn-on delay and rise time that depends on applied radio frequency signal power and is independent of above threshold steady-state current bias.

Longitudinal mode-switching dynamics in a dual external-cavity laser diode [optical neural network]

“…Olsson and Tsang [10] reported a transient time of a few external-cavity round trips when an external-cavity laser diode was driven with a step current excitation. A similar experiment was carried out by Kanjamala and Levi [11] for a laser diode that is coupled to a fiber grating external cavity.…”

Wavelength switching in multi-cavity laser diodes

“…We tentatively ascribe the discrepancy to the simplistic model used which does not take into account the effects of modelocking and the residual reflectivity of the AR coated facet. 4 FIG. 5.…”

“…The lasing wavelength prior to switching is HOT and the corresponding photoncavity is the hot cavity. 4 The nonlasing wavelength and the corresponding cavity are the cold wavelength, COLD , and cold cavity, respectively. It is to be noted that HOT can either be longer or shorter than COLD .…”