Direct laser writing of three-dimensional photonic-crystal templates for telecommunications

Abstract

The past decade has witnessed intensive research efforts related to the design and fabrication of photonic crystals. These periodically structured dielectric materials can represent the optical analogue of semiconductor crystals, and provide a novel platform for the realization of integrated photonics. Despite intensive efforts, inexpensive fabrication techniques for large-scale three-dimensional photonic crystals of high enough quality, with photonic bandgaps at near-infrared frequencies, and built-in functional elements for telecommunication applications, have been elusive. Direct laser writing by multiphoton polymerization of a photoresist has emerged as a technique for the rapid, cheap and flexible fabrication of nanostructures for photonics. In 1999, so-called layer-by-layer or woodpile photonic crystals were fabricated with a fundamental stop band at 3.9 microm wavelength. In 2002, a corresponding 1.9 microm was achieved, but the important face-centred-cubic (f.c.c.) symmetry was abandoned. Importantly, fundamental stop bands or photonic bandgaps at telecommunication wavelengths have not been demonstrated. In this letter, we report the fabrication--through direct laser writing--and detailed characterization of high-quality large-scale f.c.c. layer-by-layer structures, with fundamental stop bands ranging from 1.3 to 1.7 microm.

Polarization Stop Bands in Chiral Polymeric Three‐Dimensional Photonic Crystals

“…[11] In this report, we fabricate high-quality polymeric 3D spiral photonic crystals via direct laser writing. [12][13][14] The measured transmittance spectra of these low-index-contrast structures reveal spectral regions where the transmittance is below 5 % for one circular incident polarization and above 95 % for the other-for just eight lattice constants along the propagation direction. The experimental data are compared with scattering-matrix calculations [15,16] for the actual finite structures, leading to good agreement.…”

“…[12][13][14] Details of our process based on the commercial thick-film resist SU-8 can be found in the Experimental section and in earlier work. [13] Our structures are mechanically supported by a 2D network of bars at, or close to, the top of the 3D crystal. As the spirals are not at all mechanically connected to their neighbors, very unstable low-quality structures would result without this grid.…”

“…1a), which aims at reducing the effects of strain on the 2D grid caused by photoresist shrinkage during development. Here, we use a round (rather than a rectangular [13] ) wall in order to evenly distribute strain inside the wall. Through numerical calculations (see below), we have confirmed that the distortion of the optical properties by the 2D network is only marginal.…”

Twisted optical metamaterials for planarized ultrathin broadband circular polarizers

“…An exciting possibility in this context is provided by direct laser writing 22,23 , which ensures large flexibility in the shape of the realizable 3D metamaterial inclusions. Broadband infrared circular polarizers based on gold helical metamaterials 1 have been recently demonstrated using this technique; however, realizing these structures in the visible is hindered by the minimum realizable features imposed by the diffraction limit.…”

Mask-Directed Multiphoton Lithography

“…By scanning the fabrication voxel through reagent solution, complex three-dimensional microscale objects 1,5 have been produced with lateral feature sizes as small as ∼120 nm using synthetic materials 1 and ∼250 nm using proteins. 4 Figure 1A demonstrates our approach for mask-directed multiphoton lithography.…”