Dynamics and pulse-package oscillations in broad-area semiconductor lasers with short optical feedback

Abstract

Pulse-package oscillations in broad-area semiconductor lasers subjected to short optical feedback are experimentally observed. The pulse-package oscillation consists of a frequency component that corresponds to an external optical feedback loop with an envelop of periodic low-frequency fluctuations. However, the periodicity induced by optical feedback does not always improve the time-averaged beam profiles of the laser oscillations. We also investigated time-averaged near-field beam profiles in relation with the optical feedback dynamics.

Dynamic behaviors of a broad-area diode laser with lateral-mode-selected external feedback

“…The noise spectra and time series for the non-perfect alignment observed here show the regular LFFs consist of frequency components of external-cavity loop. This is the same as the pulse-package oscillation obtained for both narrow-stripe edge-emitting diode laser 11 and BALs 16,19 . To our knowledge, this is the first time that pulse-package oscillation is observed in diode laser with the external feedback in long-cavity regime.…”

“…Irregular LFFs have been observed frequently in diode lasers (both narrow stripe diode lasers and BALs) subjected to both conventional and phase-conjugate external feedback 9,10,14,17 . Regular LFFs have also been observed in diode laser (both narrow stripe diode lasers and BALs) with external optical feedback, but mainly in the short-cavity regime (i.e., the beating frequency of the external cavity modes is larger than the laser relaxation oscillation frequency) 11,16,19 , and rarely with long-cavity feedback (the beating frequency of the external cavity modes is less than the relaxation oscillation frequency) 9 . In the short-cavity regime, the regular LFF is named as pulse-package oscillation 11,16,19 , where periodic oscillation of the output power with the frequency of external-cavity loop is modulated by periodic LFFs; in the long-cavity regime, the regular LFF is named as synchronous Sisyphus effect 9 , where irregular fast pulses are modulated by periodic LFFs.…”

“…The complex dynamic behaviors have been studied intensively for both narrow-stripe diode lasers [8][9][10][11] and BALs [12][13][14][15][16][17][18][19] with either a conventional mirror or a phase conjugator external feedback. The dynamic behaviors of BALs have been studied with short-cavity feedback 15,16,19 , long-cavity feedback 14,17 , and tilt mirror feedback 12,18 . Different dynamic behaviors, such as low frequency fluctuations (LFFs) 14,17 , pulse-package oscillations 16,19 , have been observed in BALs subjected to external feedback.…”

“…The dynamic behaviors of BALs have been studied with short-cavity feedback 15,16,19 , long-cavity feedback 14,17 , and tilt mirror feedback 12,18 . Different dynamic behaviors, such as low frequency fluctuations (LFFs) 14,17 , pulse-package oscillations 16,19 , have been observed in BALs subjected to external feedback. Wolff et al investigated the time-resolved lateral near-and far-field distribution of BAL with lateral-modeselected external-cavity feedback numerically, and a self-Q-switched-like mode was observed in a BAL, which was operated high above the threshold 1 .…”

Spectral properties of a broad-area diode laser with off-axis external-cavity feedback

“…[1][2][3][4]6 The beam quality factor M 2 of the output beam of a BAL in slow axis can be improved up to 100 times by the off-axis external-cavity feedback technique. 4 When an external-cavity feedback (both with a conventional mirror or a phase conjugate mirror) is applied to a semiconductor laser, both narrow-stripe ridge-waveguide laser 11,12 and BALs, [13][14][15][16][17][18][19] external-cavity modes may be induced, and complex dynamics of the output beam from the laser system may take place. The spectral behavior and dynamics of BALs have been studied with short-cavity feedback, 15,16,19 long-cavity feedback, 14,17 and tilt mirror feedback, 13,18 but all these kinds of feedbacks are not the off-axis external-cavity feedback as we described previously, i.e., no spatial mode selection is achieved in these research.…”