The inventors have developed a scalable laser aperture that emits light perpendicular to the surface. The aperture can, in principle, scale to arbitrarily large sizes, offering a universal architecture for systems in need of small, intermediate, or high power.
The technology is based on photonic crystal apertures, nanostructured apertures that exhibit a quasi-linear dispersion at the center of the Brillouin zone together with a mode-dependent loss controlled by the cavity boundaries, modes, and crystal truncation. Open Dirac cavities protect the fundamental mode and couple higher-order modes to lossy bands of the photonic structure. The technology was developed with an open-Dirac electromagnetic aperture, known as a Berkeley Surface Emitting Laser (BKSEL).
The inventors demonstrate a subtle cavity-mode-dependent scaling of losses. For cavities with a quadratic dispersion, detuned from the Dirac singularity, the complex frequencies converge towards each other based on cavity size. While the convergence of the real parts of cavity modes towards each other is delayed, going quickly to zero, the normalized complex free-spectral range converges towards a constant solely governed by the loss rate of Bloch bands. The inventors show that this unique scaling of the complex frequency of cavity modes in open-Dirac electromagnetic apertures guarantees the single-mode operation of large cavities.
The technology demonstrates scaled-up single-mode lasing and is confirmed from far-field measurements. By eliminating limits on electromagnetic aperture size, the technology will enable groundbreaking applications for devices of all sizes, operating at any power level.
Single aperture cavities are bounded by higher-order transverse modes, fundamentally limiting the power emitted by single-mode lasers, as well as the brightness of quantum light sources. Electromagnetic apertures support cavity modes that rapidly become arbitrarily close with the size of the aperture. The free-spectral range of existing electromagnetic apertures goes to zero when the size of the aperture increases. As a result, scale-invariant apertures or lasers have remained elusive until now.
Surface-emitting lasers have advantages in scalability over commercially widespread vertical-cavity surface-emitting lasers (VCSELs). When a photonic crystal is truncated to a finite cavity, the continuous bands break up into discrete cavity modes. These higher-order modes compete with the fundamental lasing mode and the device becomes more susceptible to multimode lasing response as the cavity size increases.
Current lasers all fail at a relatively small scale on the order of tens of microns by tens of microns, necessitating multimode systems. In contrast, this technology offers a single, arbitrarily scalable aperture laser with many advantages.
- efficient, because power is emitted from all material in the aperture
- the fundamental mode depletes gain for other modes
- can be pumped both electrically and optically
- can be manufactured with conventional fabrication techniques such as CMOS nanofabrication; the technology contains structures on the order of the wavelength or smaller
- more scalable than any other single aperture lasers, offering a singular solution for small size, weight, and power (SWAP) devices
- can be implemented in any frequency, ranging from microwaves, terahertz, infrared, optics, and beyond
Name: Laleh Shayesteh