High density ultrahigh resolution patterning with desired shape and size is a crucial requirement in nanotechnology and its applications. Electron beam lithography (EBL) is the most widely used lithography tool for these applications. However, achieving cost-effective patterning with sub-10-nm critical dimension has been challenging due to the inherent tradeoff between resolution and throughput. In this paper, we present cost-effective new processes associated with EBL technique, which include optimized resist selection and processing as well as sonicated cold development process. Using this process, we demonstrate sub-10-nm diameter metal dots at a pitch of ~34 nm and sub-15 nm wide metal lines. Based on the same processes, we demonstrate the fabrication of u-shaped split ring resonator array of different metals with smallest fabricated resonator with ~60 nm size and v-shape SRRs with the smallest gap spacing of ~30 nm. By adjusting the SRR gap spacing through its arm length and opening angle, we have successfully demonstrated magnetic and electric resonances across the visible and ultraviolet range.
We propose a scheme based on two-ring resonator system that can realize flat delay and transmission response with
delay-bandwidth product (DBP) higher that those achieved in previously proposed schemes. The spectrum flatness and
DBP are two key parameters that characterize the maximum number of bits that can be buffered without distortion for
certain signal operating bandwidth. Simple time domain simulation shows that our scheme can achieve the same
buffering time with 2 to 4 times smaller number of modules, which indicates DBP of 2 to 4 times larger than those of
side-coupled ring structure and coupled resonator optical.
We propose a finesse enhancement scheme by a simple two-ring system, in which the resonance finesse is dependent on
the relative intensity buildup of the second ring with respect to the first. In lossless case, it is possible to obtain finesse
two orders of magnitude higher than that of the single ring system. The two-ring system is fabricated in silicon-on-insulator
using deep UV (DUV) lithography and shown to exhibit the finesse of 100 to 300. The associated finesse
enhancement of 20 is in a good agreement with the theory.
In this proceeding, we present for the first time, a nested-ring Mach-Zehnder interferometer (NRMZI) on SOI (Silicon-on-
insulator), realized using a CMOS based process. We show that the device operates in two propagating resonance
modes: (1) The inner-loop resonant mode due to strong build-up inside the inner-ring and (2) the double Fano-resonance
mode due to strong light interaction with the outer loop. The experimental data shows that the inner-loop resonance is
highly sensitive to the MZI arm imbalance as compared to the double-Fano resonance mode. With such considerations, a
good fit is acquired between theory and experiment.
We present a transfer matrix analysis of a 2-D filter to study its frequency response functions. The (M × N) array consists of N independent columns of micro-ring resonators side-coupled to two channel bus waveguides, with equal spacing between columns and each column consisting of M coupled resonators. We show that the bandgap of the 2-D structure is a superposition of the non-overlapping bandgap of the two 1-D arrays. This non-overlapping property can be
used to realize the "near-ideal" filter with flat and sharp passband, negligible sidelobes in the stop bands, and linear
phase response over 80% of the passband. The existence of defect mode in linear and lossless ring resonator arrays is also demonstrated. The defect can be introduced by removing one ring or by making one ring bigger or smaller. Defect states within the photonic bandgaps behave like either donor or acceptor modes similar to other photonic crystals. The results based on transfer matrix model shows reasonable agreement with finite difference time domain (FDTD) simulations.