Signature of Wave Chaos in Spectral Characteristics of Microcavity Lasers

We report an experimental investigation on the spectra of fully chaotic and nonchaotic microcavity lasers under continuous-wave operating conditions. It is found that fully chaotic microcavity lasers operate in single mode, whereas nonchaotic microcavity lasers operate in multimode. The suppression of multimode lasing for fully chaotic microcavity lasers is explained by large spatial overlaps of the resonance wave functions that spread throughout the two-dimensional cavity due to the ergodicity of chaotic ray orbits.

Figure 1

(a) Stadium cavity and (b) elliptic cavity. (c),(d) Optical microscope images of the fabricated lasers, where both cavities have an area $S=8748\mu {\mathrm{m}}^2$ and an aspect ratio $p=0.5$.

Figure 2

Spectra of the stadium cavity laser with a cavity area $S=8748\mu {\mathrm{m}}^2$ and an aspect ratio $p=0.5$ for various current values. The threshold current is approximately 74 mA.

Figure 3

Spectra of the elliptic cavity laser with a cavity area $S=8748{\mu \mathrm{m}}^2$ and an aspect ratio $p=0.5$ for various current values. The threshold current is approximately 34 mA.

Figure 4

Injection current dependence of the number of peaks in the spectra of (a) the stadium cavity lasers and (b) the elliptic cavity lasers with various cavity areas $S$. In both (a) and (b), the aspect ratio is $p=0.5$.

Figure 5

Injection current dependence of the number of peaks in the spectra of (a) the stadium cavity lasers and (b) the elliptic cavity lasers with various aspect ratios $p$. In (a), the radius $R$ is fixed as $25\mu \mathrm{m}$, (i.e., the area for $p=0.5$ is $S=4463\mu {\mathrm{m}}^2$). In (b), the areas of the elliptic cavities are the same as that of the stadium cavity with $p=0.5$.

Figure 6

(a),(b) Spatial intensity patterns of low-loss modes in a quarter of the stadium cavity, where (b) is a scarred mode with localization along a rectangular ray orbit. (c),(d) Spatial intensity patterns of whispering-gallery modes in a quarter of the elliptic cavity, where the radial mode number is $n_r=1$ for (c) and $n_r=5$ for (d).

Figure 7

Histogram of overlap $C$ defined by Eq. (1) between two low-loss modes for the stadium cavity (solid) and elliptic cavity (dotted).