Fabrication by means of x-ray lithography of two-dimensional GaAs/AlGaAs photonic crystals with an unconventional unit cell

Abstract

Two-dimensional photonic crystals have been fabricated by x-ray lithography and reactive ion etching on an air/GaAs/AlGaAs asymmetric waveguide. The shape of the lattice unit cell has been varied by exploiting x-ray diffraction effects and nonlinear response of resists during the development process. Rings with or without a central pillar have been fabricated with a resolution down to 50 nm. Lithographic details are described to show the accuracy of this fabrication technique. Optical characterization has been performed showing the presence of a well defined photonic band structure as well as band anti-crossing. The results are discussed and compared with theoretical calculations of the photonic band dispersion. Structures with high dielectric fraction are shown to yield photonic modes with small line widths and low propagation losses. The reliability and the precise control of the fabricated sample structures make this lithographic method useful for a full investigation of optical properties on the dependence of the lattice unit cell shape.

Resonant second-harmonic generation in a GaAs photonic crystal waveguide

“…The fabrication procedure consists of epitaxial growth, electron-beam and x-ray lithography, and reactive-ion etching. 19 A scanningelectron micrograph of the sample is shown in the inset to Fig. 1; the etch depth is about 1 m. Variable-angle linear reflectance on this sample yielded the dispersion of photonic bands in the 0.5-1.1 eV energy range.…”

Ultra-low power generation of twin photons in a compact silicon ring resonator

“…Silicon ring resonators [10,12] are excellent candidates for such sources. In fact, they can have several modes in the telecom band with extremely sharp line widths (on the order of tens of µeV) and they are fabricated using top down approaches [13,14] compatible with CMOS technology [15,16]. Furthermore, they are well suited to optical fiber butt-coupling.…”

Stimulated and spontaneous four-wave mixing in silicon-on-insulator coupled photonic wire nano-cavities

“…A common way to enhance optical nonlinearities is to use optical confinement to increase the overlap between the electromagnetic field and the nonlinear material. In these regards, photonic crystals (PhCs) [7], and in particular PhC nano-cavities [8], allow for the confinement of light to volumes comparable to the cube of their wavelength in the material and can be fabricated using several top-down approaches [9,10] compatible with CMOS technology [11,12]. PhC cavities have been employed to enhance basic cavity quantum electrodynamics effects [13,14], to demonstrate ultra-low threshold lasing [15,16] and to enhance optical nonlinear effects in silicon [17][18][19][20].…”