Thermally Controlled Onset of Spatially Incoherent Emission in a Broad-Area Vertical-Cavity Surface-Emitting Laser

• Published in: IEEE journal of selected topics in quantum electronics Vol. 15; no. 3; pp. 555 - 562
• Main Authors: Craggs, G., Verschaffelt, G., Mandre, S.K., Thienpont, H., Fischer, I.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2009; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bias; Chirp; Emission; Emission analysis; Holes; Laser theory; Lasers; Lenses; Optical control; Optical pulses; Pulse measurements; Pulse modulation; Semiconductor laser; spatial coherence; Surface emitting lasers; thermal effects; Thermal expansion; Thermal lensing; Vertical cavity surface emission lasers; Vertical cavity surface emitting lasers; vertical-cavity surface-emitting laser (VCSEL)
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2009.2016355

We present an experimental study of the physical process that leads to spatially incoherent, nonmodal emission in broad-area vertical-cavity surface-emitting lasers. We show that this special emission regime that occurs in pulsed operation of these lasers is due to a combination of a spatially distributed thermal or refractive index gradient (thermal lens) and thermal expansion of the cavity during the pulse (thermal chirp). Our measurements are based on preinstalling a thermal lens through a current bias, and subsequently, modulating a pulse onto the bias. This approach allows us to independently investigate the role of both thermal effects in the onset of nonmodal emission.