Sensitive control of broad-area semiconductor lasers by cavity shape
Abstract
The ray dynamics of optical cavities exhibits bifurcation points: special geometries at which ray trajectories switch abruptly between stable and unstable. A prominent example is the Fabry–Perot cavity with two planar mirrors, which is widely employed for broad-area semiconductor lasers. Such cavities support lasing in a relatively small number of transverse modes, and the laser is highly susceptible to filamentation and irregular pulsations. Here, we demonstrate experimentally that a slight deviation from this bifurcation point (planar cavity) dramatically changes the laser performance. In a near-planar cavity with two concave mirrors, the number of transverse lasing modes increases drastically. While the spatial coherence of the laser emission is reduced, the divergence angle of the output beam remains relatively narrow. Moreover, the spatiotemporal lasing dynamics becomes significantly more stable compared to that in a Fabry–Perot cavity. Our near-planar broad-area semiconductor laser has higher brightness, better directionality, and hence allows shorter integration times than an incandescent lamp while featuring sufficiently low speckle contrast at the same time, making it a vastly superior light source for speckle-free imaging. Furthermore, our method of controlling spatiotemporal dynamics with extreme sensitivity near a bifurcation point may be applied to other types of high-power lasers and nonlinear dynamic systems.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 01, 2022
- Source ID
- 10.1063/5.0087048
Entities
People
- Hui Cao
- Kyungduk Kim
- Ortwin Hess
- Qi Jie Wang
- Stefan Bittner
- Stefano Guazzotti
- Yongquan Zeng
- Yuhao Jin
Organizations
- CentraleSupélec
- European Regional Development Fund
- Fondation CentraleSupélec
- Ministry of Higher Education and Research
- Nanyang Technological University
- Office of Naval Research
- Science Foundation Ireland
- Trinity College Dublin
- Yale University