Multi-level diffractive optics for single laser exposure fabrication of telecom-band diamond-like 3-dimensional photonic crystals

Abstract

We present a novel multi-level diffractive optical element for diffractive optic near-field lithography based fabrication of large-area diamond-like photonic crystal structure in a single laser exposure step. A multi-level single-surface phase element was laser fabricated on a thin polymer film by two-photon polymerization. A quarter-period phase shift was designed into the phase elements to generate a 3D periodic intensity distribution of double basis diamond-like structure. Finite difference time domain calculation of near-field diffraction patterns and associated isointensity surfaces are corroborated by definitive demonstration of a diamond-like woodpile structure formed inside thick photoresist. A large number of layers provided a strong stopband in the telecom band that matched predictions of numerical band calculation. SEM and spectral observations indicate good structural uniformity over large exposure area that promises 3D photonic crystal devices with high optical quality for a wide range of motif shapes and symmetries. Optical sensing is demonstrated by spectral shifts of the Gamma-Zeta stopband under liquid emersion.

Holographic fabrication of 3D photonic crystals using silicon based reflective optics element

“…So far, holographic lithography has been successful in fabricating large-volume PhC templates at sub-micro/nanoscales [9][10][11][12][13][14][15][16][17]. It is an adaptive method because the structure and symmetry of 3D PhC templates can be controlled by the beam propagating directions, the number of the interfering beams, the beam intensities, their respective polarizations, and their relative phases [18,19].…”

“…Very recently, a single diffractive [11][12][13][14] or reflective [15][16][17] optical element has been used for laser holographic fabrication of 3D PhC structures in order to reduce the complexity of the optical setup and improve the optical stability. A flat-top prism and multi-layer phase mask have been demonstrated to fabricate diamond-like PhC templates by introducing a phase difference among the diffracted beams [12][13][14][15][16][17][18][19]. Using a flat-top prism, our previous paper has fabricated a woodpile PhC template by introducing a phase shift π of a single side beam relative to others using a glass cover slip as a phase modulation [16].…”

Five beam holographic lithography for simultaneous fabrication of three dimensional photonic crystal templates and line defects using phase tunable diffractive optical element

“…a flat-top prism [10,11]) or a diffractive optical element (e.g. a phase mask [12][13][14][15][16]) has recently been used for the laser holographic fabrication of photonic crystal structures. A flat-top prism has been used for the fabrication of diamond-like or woodpile photonic crystal templates, using a polarization effect with a configuration consisting of four linearly polarized side beams arranged symmetrically around a circularly polarized central beam [11].…”

“…A flat-top prism has been used for the fabrication of diamond-like or woodpile photonic crystal templates, using a polarization effect with a configuration consisting of four linearly polarized side beams arranged symmetrically around a circularly polarized central beam [11]. Multi-layer phase masks [13,14] have been demonstrated for the fabrication of diamond-like photonic crystal templates by introducing a phase difference among the diffracted beams by changing the distance between two orthogonally oriented gratings. However the phase difference is not adjustable once the phase mask is fabricated [13,14].…”

“…Multi-layer phase masks [13,14] have been demonstrated for the fabrication of diamond-like photonic crystal templates by introducing a phase difference among the diffracted beams by changing the distance between two orthogonally oriented gratings. However the phase difference is not adjustable once the phase mask is fabricated [13,14]. Overall the single-beam and single-exposure processes using a single optical element in holographic lithography have drastically reduced the fabrication complexity and produced the complex diamond-like photonic lattice where there is a larger photonic bandgap compared to a simple face-centered-cubic (FCC) structure [13,14].…”