Transition of optical regime in miniaturized optical systems: light interactions beyond the refraction limit

We investigate the transition of optical regimes of miniaturized optical systems using two canonical examples, where the refraction of light limits the system performance. A ball-lens and a solid immersion lens (SIL) are considered, whose refractive responses can be intuitively described by ray optics when the system size is relatively large. For miniaturized systems, the optical response differs from that of conventional large systems. Since such new responses occur when the refractive response of light start to disappear, this boundary is called the refraction limit. Our intension is to bring insights into new phenomena beyond such a boundary.. First, the refraction limit of the ball-lens is identified with three different criteria: the focal length, the spot size, and the amount of depolarization. The light confinement effect of nanoscale SILs, which have an intentionally deformed shape, demonstrates the diminishing effect of the refractive response of light. Likewise, beyond the refraction limit of the miniaturized systems, the signature of refractive degradations vanishes, and the shape errors of elements become negligible.