Microstar cavities: An alternative concept for the confinement of light

Abstract

In this Rapid Communication we report on an alternative concept to confine light in a microcavity. The traditional approaches are either based on total internal reflection at a dielectric interface or utilize a photonic band gap in a periodic structure such as Bragg mirrors or photonic crystals. In contrast, the concept presented here completely avoids these mechanisms. The light confinement is rather based on rays that are sequentially transmitted perfectly at the cavity's interface using Brewster's angle. These rays leave and reenter the cavity on closed periodic orbits without loss of intensity. Accordingly, in wave optics, high-quality modes with fascinating properties arise.

Whispering-Gallery Sensors

“…There is still significant progress to be made in the development of WGM microresonator structures, such as deformed microresonators, 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 endoscopic sensing probes, 145 , 146 and WGM sensors in chip-based microfluidics channels. 147 Not only will these lead to further improvement in device sensitivity but they will also allow for the detection of analytes that are beyond the reach of current techniques.…”

Ray–Wave Correspondence in Microstar Cavities

“…As in the wave regime discussed in ref. [ 31 ], the most long-lived mode localizes along the stable periodic orbit passing through the spikes of the microstar; see Figure 9 d. However, additional long-lived modes exist in the semiclassical regime that also pass through the spikes but have more intensity maxima in radial direction; see Figure 9 a–c. Thus, a classification of these modes with a radial mode number l is suitable.…”

“…A microstar is a quasi-two-dimensional cavity with homogeneous refractive index n [ 31 ]. It is characterized by the number of spikes .…”

“…In a former article [ 31 ], an alternative concept for light confinement was introduced which is completely different from the traditional whispering-gallery design. The perfect transmissions at Brewster’s angle are utilized such that a ray can leave (and reenter) the cavity without partial back reflection.…”