Simultaneous direct holographic fabrication of photonic cavity and graded photonic lattice with dual periodicity, dual basis, and dual symmetry

Abstract

For the first time, to the authors' best knowledge, this paper demonstrates the digital, holographic fabrication of graded, super-basis photonic lattices with dual periodicity, dual basis, and dual symmetry. Pixel-by-pixel phase engineering of the laser beam generates the highest resolution in a programmable spatial light modulator (SLM) for the direct imaging of graded photonic super-lattices. This technique grants flexibility in designing 2-D lattices with size-graded features, differing periodicities, and differing symmetries, as well as lattices having simultaneously two periodicities and two symmetries in high resolutions. By tuning the diffraction efficiency ratio from the SLM, photonic cavities can also be generated in the graded super-lattice simultaneously through a one-exposure process. A high quality factor of over 1.56 × 10 for a cavity mode in the graded photonic lattice with a large super-cell is predicted by simulations.

Generation of over 1000 Diffraction Spots from 2D Graded Photonic Super-Crystals

“…Multiple-beam laser interference lithography has been used for the holographic fabrication of GPSCs [12][13][14]. Here the interference pattern is used to design the pattern for the electron-beam lithography and also as an input for the FDTD simulation of E-field intensity and reflection from the GPSC.…”

“…Very recently, graded photonic super-crystals (GPSCs) have been fabricated through the interference lithography by two sets of multiple beams arranged in a cone geometry [12][13][14]. The GPSC has two sets of lattices: the rod size (or hole size) increases gradually along one direction in one set of lattices while the other set decreases their sizes gradually.…”

“…The GPSC has two sets of lattices: the rod size (or hole size) increases gradually along one direction in one set of lattices while the other set decreases their sizes gradually. GPSC has dual period and even dual symmetry: The square lattices in GPSC have a small period while graded regions have their own symmetry and period [12][13][14]. GPSCs can be used to enhance the broadband light trapping in an Si solar cell, broadband light extraction from organic light emitting diode, and to form a resonance cavity at the boundary of graded and less-graded regions [15][16][17].…”

Extraordinary Light-Trapping Enhancement in Silicon Solar Cell Patterned with Graded Photonic Super-Crystals

“…The appearance of many photonic bands, up to 144, below the photonic band gap or cavity mode [25] indicates a large density of optical states in the GPSC. When light is coupled into the structure, we expect resonance modes in the GPSC, waveguide modes in the horizontal plane in the silicon and ITO regions without GPSC, and leaky resonance modes in the vertical direction.…”

“…As shown in Figure 1a, a glass slide covered with a 300 nm layer of indium-tin oxide (ITO) (n = 1.8) was spin-coated with a positive resist, then patterned with the newly discovered GPSC [25,26], as shown in Figure 1b, and finally etched to a depth of 200 nm. A gold film was then deposited, and the positive resist was lifted off.…”