Applications for this technology are currently found in telecommunications, spectroscopy, laser printing, biological tissue analysis, and meteorology.
This invention exhibits a photonic-crystal surface-emitting laser (PCSEL) with an accidental Dirac point. PCSELs include a gain medium
electromagnetically coupled to a photonic crystal; however, in this invention, the energy band
structure exhibits a Dirac cone of linear dispersion at the center of
the photonic crystal's Brillouin zone. Because the Dirac point is at the Brillouin zone center, it is
called an accidental Dirac point. This is of great importance because tuning the photonic crystal's band
structure (e.g., by changing the photonic crystal's dimensions or
refractive index) to exhibit an accidental Dirac point increases the
photonic crystal's mode spacing by orders of magnitudes and reduces or
eliminates the photonic crystal's distributed in-plane feedback. Thus,
the photonic crystal can act as a resonator that supports single-mode
output from the PCSEL over a larger area than is possible with
conventional PCSELs, which have quadratic band edge dispersion. Because
output power generally scales with output area, this increase in output
area results in higher possible output powers.
Distributed feedback (DFB) lasers and vertical-cavity surface-emitting lasers (VCSELs) rely on one-dimensional feedback structures to provide relatively high-power, single-mode beams. Unfortunately, these lasers suffer from intrinsic drawbacks: DFB lasers and other edge-emitting sources tend to suffer from catastrophic optical damage at their facets, and the VCSELs' output powers are usually limited by their small cavity sizes.
On the other hand, conventional photonic-crystal surface-emitting lasers (PCSELs), have a higher functionality than the previously mentioned lasers. However, the lasing areas of PCSELs are limited by two fundamental constraints.
First, the mode spacing decreases as the cavity area increases, which
promotes multi-mode lasing. Second, the distributed in-plane feedback
localizes the lasing fields to individual sections, which promotes
multi-area lasing. Since the output power scales with the lasing area,
these constraints limit the maximum output power of a single-mode beam
emitted by a PCSEL.
- Increased orders of magnitude in photonic crystal mode spacing
- Reduction in the crystal's distributed in-plane feedback
- Greater output power and output area