Square-wave oscillations in semiconductor ring lasers with delayed optical feedback

by Mashal, L., Van der Sande, G., Gelens, L., Danckaert, J. and Verschaffelt, G.
Abstract:
We analyze experimentally and theoretically the effects of delayed optical cross-feedback in semiconductor ring lasers. We show that under appropriate conditions, feeding of only one directional mode back into the counter-propagating mode leads to square-wave oscillations. In this regime, the laser switches regularly between the two counter-propagating modes with a period close to twice the roundtrip time in the external feedback loop. We find that these oscillations are robust and appear for a wide range of parameters as long as a small asymmetry in the linear coupling between both modes is present. We show that by increasing the feedback strength or the injection current, the square-wave oscillations gradually disappear. Due to noise, mode-hopping between stable lasing in one directional mode and square wave oscillations is observed in this transition region.
Reference:
Square-wave oscillations in semiconductor ring lasers with delayed optical feedback Mashal, L., Van der Sande, G., Gelens, L., Danckaert, J. and Verschaffelt, G., Optics Express, volume 20, pp. 22503–22516, 2012.
Bibtex Entry:
@article{mashal_square-wave_2012,
	title = {Square-wave oscillations in semiconductor ring lasers with delayed optical feedback},
	volume = {20},
	copyright = {© 2012 OSA},
	issn = {1094-4087},
	url = {http://www.osapublishing.org/abstract.cfm?uri=oe-20-20-22503},
	doi = {10.1364/OE.20.022503},
	abstract = {We analyze experimentally and theoretically the effects of delayed optical cross-feedback in semiconductor ring lasers. We show that under appropriate conditions, feeding of only one directional mode back into the counter-propagating mode leads to square-wave oscillations. In this regime, the laser switches regularly between the two counter-propagating modes with a period close to twice the roundtrip time in the external feedback loop. We find that these oscillations are robust and appear for a wide range of parameters as long as a small asymmetry in the linear coupling between both modes is present. We show that by increasing the feedback strength or the injection current, the square-wave oscillations gradually disappear. Due to noise, mode-hopping between stable lasing in one directional mode and square wave oscillations is observed in this transition region.},
	language = {EN},
	number = {20},
	urldate = {2016-11-07},
	journal = {Optics Express},
	author = {Mashal, L. and {Van der Sande}, G.  and Gelens, L. and Danckaert, J. and Verschaffelt, G.},
	month = sep,
	year = {2012},
	pages = {22503--22516},
	file = {Full Text PDF:/home/jan/.zotero/zotero/djuw86a6.default/zotero/storage/Q8Q49FEZ/Mashal et al. - 2012 - Square-wave oscillations in semiconductor ring las.pdf:application/pdf;Snapshot:/home/jan/.zotero/zotero/djuw86a6.default/zotero/storage/W8EVT47G/abstract.html:text/html}
}