Vertical-cavity surface-emitting lasers (VCSELs)
Fig. 4: A typical VCSEL device formed by an active layer of semiconductor material between two Bragg reflectors
VCSELs are a type of semiconductor lasers with the beam emission perpendicular to the top surface (see Figure 4), contrary to conventional edge-emitting semiconductor lasers. Their main advantages are the extremely small dimensions and the high output power. A single-emitter of a VCSEL can be as small as a few microns wide and tens of microns tall, leading to practical sizes less than 100 microns in all dimensions. Practical VCSELs made of hundreds of emitters can reach multiple Watts of output power. VCSELs are used in various laser products, including computer mice, fiber-optic communications, laser printers, face recognition and even smart-glasses.
Recent work in the CNQO has focused on VCSELs with frequency selective feedback in collaboration with Thorsten Ackemann’s group at Strathclyde. For example we have shown that laser cavity solitons that have been discovered at Strathclyde in 2008, can interact with each other and reveal unexpected locking behaviour (see Fig. 5). More recently we reported on the experimental observation of mode-locked spatial laser solitons in a VCSEL with frequency-selective feedback from an external cavity. These spontaneously emerging and long-term stable spatiotemporal structures have a pulse length shorter than the cavity round-trip time (see Figure 6) and paved the way to completely independent cavity light bullets.
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| Fig. 5: Interference fringe visibility (black) and phase (green) between two laser cavity solitons (spots in the inset) | Fig. 6: Example of harmonic mode locking. Left panels: Time series, Pulses, rf spectra. Right panel: long-time vs cavity-time representations of the dynamics, |
Recent References
P. V. Paulau, C. McIntyre, Y. Noblet, N. Radwell, W. J. Firth, P. Colet, T. Ackemann and G.-L. Oppo, Adler Synchronization of Spatial Laser Solitons Pinned by Defects, Phys. Rev. Lett, 108, 213904 (2012).
F. Gustave, N. Radwell, C. McIntyre, J. P. Toomey, D. M. Kane, S. Barland, W. J. Firth, G.-L. Oppo, and T. Ackemann, Observation of Mode-Locked Spatial Laser Solitons, Phys. Rev. Lett 118, 044102 (2017).