Young Mo Kang

Realization of a narrowband single wavelength microring mirror

We present a small footprint narrowband on-chip mirror made by integration of a distributed Bragg reflector (DBR) inside a microring resonator. The DBR covers half of the ring’s circumference and is only reflective at one of the ring resonances. Design, fabrication, and characterization of the proposed device are presented. A single reflection peak with maximum power reflectivity of 92.3% and full width at half maximum of 0.4 nm is demonstrated. The device has potential application as an in-line mirror for low-threshold, narrow linewidth single mode laser diodes.

Engineering the spectral reflectance of microring resonators with integrated reflective elements

We present analysis and design of microring resonators integrated with reflective elements to obtain custom wavelength-selective devices. We introduce a graphical method that transforms the complicated design problem of the integrated structure into a simple task of designing a reflective element possessing an appropriate reflection profile. Configurations for obtaining a comb mirror, a single peak mirror, an ultranarrow band transmission filter, and a sharp transition mirror are presented as examples.

Quasicontinuous refractive index tailoring of SiNx and SiOxNy for broadband antireflective coatings

A broadband antireflective coating for silicon was fabricated by tailoring the compositions of SiNx and SiOxNy during conventional plasma enhanced chemical vapor deposition. The coating’s refractive index was quasicontinuously graded, e.g., from 3.22 to 1.44 at 1550 nm. Over the 280–3300 nm wavelength range, the reflectance was below 8% peak and 4.3% average. The deposited stack was composed of dense dielectric materials. This enables patterning and processing into robust devices after coating deposition. Using single layer ellipsometry data, the transfer matrix method was applied to predict the multilayer coating’s reflectance spectra. The results showed good agreement with experimental data.

Cylindrical Coordinates Coupled Mode Theory

We present a cylindrical coordinates coupled mode formulation for coupling between two degenerate modes of a traveling wave resonator. The resonator is assumed to have rotational symmetry and therefore two degenerate modes propagating in opposite directions. We analyze coupling of the resonance modes in space due to a perturbation in the resonator and derive first-order coupling equations. We also present an application of the method in modeling the mode coupling in a ring resonator with an integrated distributed Bragg reflector. For the presented structure, the results from coupled mode analysis agree with the finite elements method simulation results, and the method dramatically reduces the simulation time from 2 h to less than 5 min.

Semi-analytical modeling of microring resonators with distributed Bragg reflectors

A semi-analytical method for fast simulation of microring resonators with distributed Bragg reflectors (DBR-MRR) is presented. Under the low loss condition, the structure exhibits a spectral response similar to that of a sampled-grating distributed Bragg reflector (SGDBR). However, the DBR-MRR can achieve higher reflectivity with significantly fewer gratings due to multiple reflection encounters with the same DBR gratings.

Fast and accurate finite element analysis of large-scale three-dimensional photonic devices with a robust domain decomposition method

A fast and accurate full-wave technique based on the dual-primal finite element tearing and interconnecting method and the second-order transmission condition is presented for large-scale three-dimensional photonic device simulations. The technique decomposes a general three-dimensional electromagnetic problem into smaller subdomain problems so that parallel computing can be performed on distributed-memory computer clusters to reduce the simulation time significantly. With the electric fields computed everywhere, photonic device parameters such as transmission and reflection coefficients are extracted. Several photonic devices, with simulation volumes up to 1.9×10(4) (λ/n(avg))3 and modeled with over one hundred million unknowns, are simulated to demonstrate the application, efficiency, and capability of this technique. The simulations show good agreement with experimental results and in a special case with a simplified two-dimensional simulation.