This is in contrast to channel waveguides for which in-guide reflections always propagate back toward the source.
#On fisheye lens free#
The fact that these beams are free to propagate in in-plane directions allows for diagonally set features to generate oblique reflections and thereby direct the scattered radiation away from its originating direction. Nagatsuma, “ Half–Maxwell fisheye lens with photonic crystal waveguide for the integration of terahertz optics,” Opt. With in-slab beamforming techniques and integrated optics, this mode can propagate as a well-defined collimated beam. Teich, Fundamentals of Photonics ( John Wiley & Sons, 2019).
The fundamental TE 0 slab-mode exhibits no cutoff or leakage at lower frequencies, and hence, it is highly broadband and of low dispersion. Both are enabled by oblique in-slab reflections that are collected at a location other than the originating lens, which is not attainable using ordinary single-mode channel waveguides.Ī dielectric slab waveguide supports infinite in-plane propagating modes, and although this presents complexities in comparison to single-mode channel waveguides, there are also several advantages. We present two prototype systems to demonstrate the versatility of this concept, namely, a diagonally set distributed Bragg reflector as a frequency-division diplexer for terahertz communications and an attenuated total reflection-based liquid sensor.
#On fisheye lens manual#
Terahertz technology will benefit from such broadband slab-confined beams to replace free-space optics toward compact, mass-producible systems that do not require manual optical alignment. Although it is challenging to match to the low-index focus of the lens while maintaining adequate field confinement for a close approximation of a point source, integrated dielectric slot waveguides prove highly suitable, yielding collimators of 90% efficiency and bandwidth greater than one octave.
We present a paradigm for integrated photonic devices based on broadband slab-confined collimated beams that are launched with half-Maxwell fisheye lenses.