Order Microring Research Articles

Compact Wavelength Selective Crossbar Switch with Cascaded First Order Micro-Ring Resonators

We demonstrate a compact 4×4 wavelength selective switch with 50% fewer electrical signal pads as compared with our previous generation. We report loss and crosstalk for different paths of the switch. We measure median loss of 5.32 dB and worst case crosstalk of −35 dB. The microring resonators tune by more than one free spectral range, which is an improvement over our previous generation of switches. This switch can support 8 channels at 400 GHz spacing. We conclude that it is possible to drive both microring resonators with the same voltage and separate control is not required if the fabrication variation reduces in the future.

Automatic Resonance Alignment of High-Order Microring Filters

Automatic resonance alignment tuning is performed in high-order series coupled microring filters using a feedback system. By inputting only a reference wavelength, a filter is tuned such that passband ripples are dramatically reduced compared to the initial detuned state and the passband becomes centered at the reference. The method is tested on 5th order microring filters fabricated in a standard silicon photonics foundry process. Repeatable tuning is demonstrated for filters on multiple dies from the wafer and for arbitrary reference wavelengths within the free spectral range of the microrings.

Low-voltage and compact polymeric optical switches using a Mach–Zehnder interferometer and N side-coupled electro-optic microrings

Universal structure and thorough analysis were proposed for a kind of polymer optical switch using N-th order microring resonator side-coupled Mach–Zehnder interferometer (MRR-SC-MZI). Formulation and expression of output power, insertion loss and crosstalk were derived, and detailed design and optimization were carried out. Analytical results indicate that all devices for N≥1 can perform normal switching function, and 8≥N≥2 is preferred for dropping the driving voltage below 5V. For the seven MRR-SC-MZI EO switches (N=2–8) whose cross-state voltages are within 0–2.32V, their bar-state voltages are within 0.96–4.83V and their insertion losses are within 0.35–0.85dB at bar state, whereas those within 0.14–1.70dB at cross state; their crosstalk are within −20.79 to −31.11dB at bar state, whereas those are within −13.86 to −20.36dB at cross state; their 3-dB electrical bandwidths are within 18.5–28.0GHz, and 3-dB optical bandwidths for the two output ports are within 18.1–40.0GHz and 32.0~55GHz, respectively. Comparison indicates that the driving voltages of the proposed MRR-SC-MZI switching devices are 10–250 times smaller than those of the traditional MZI EO switches with the same EO region length, device length and structural parameters. Therefore, due to small footprint size and low driving voltage, this switching configuration can be densely integrated onto optoelectronic chips.

4$\,\times\,$44 Gb/s Packet-Level Switching in a Second-Order Microring Switch

We demonstrate simultaneous switching of wavelength-division-multiplexed (WDM) data consisting of four 44-Gb/s channels (176 Gb/s total) through an electro-optically active second-order microring switch with a 0.7-ns rise and a 3.4-ns fall time. The higher order microring device allows fast simultaneous switching of multiple high data rate WDM channels. We verify the correct active switching operation and low resultant power penalties on both switch output ports. The ability to switch multiple high data rate channels simultaneously at high speed with low power consumption makes higher order ring switches attractive components for silicon photonic switching fabrics.

Theoretical analysis of a thermal-optical tunable filter based on Vernier effect of cascade microring resonators

A thermal-optical tunable filter based on the Venier effect of cascade microring resonator, which can expand the Free-Spectrum-Range (FSR) and the tuning range, is designed and simulated. The FSR of the filter with a radius of 48 m for the first order and 50 m for the second order microring can be expanded to 76.5 nm, which is at present the largest FSR to our best knowledge. A tuning range covering all of the above mentioned FSR can be reached under 103.1 mW heating power, which is also the largest one for silicon based thermal-optic tunable microring resonator filers. The response time, calculated by finite-element-method, of the designed tunable filter with 50 m radius ring is 3.5 s for the rise edge and 0.8 s for the fall edge.

A 320 Gb/s-Throughput Capable 2$\,\times\,$2 Silicon-Plasmonic Router Architecture for Optical Interconnects

We demonstrate a 2 × 2 silicon-plasmonic router architecture with 320 Gb/s throughput capabilities for optical interconnect applications. The proposed router platform relies on a novel dual-ring Dielectric-Loaded Surface Plasmon Polariton (DLSPP) 2 × 2 switch heterointegrated on a Silicon-on-Insulator (SOI) photonic motherboard that is responsible for traffic multiplexing and header processing functionalities. We present experimental results of a Poly-methyl-methacrylate (PMMA)-loaded dual-resonator DLSPP waveguide structure that uses two racetrack resonators of 5.5 μm radius and 4 μ m-long straight sections and operates as a passive add/drop filtering element. We derive its frequency-domain transfer function, confirm its add/drop experimental spectral response, and proceed to a circuit-level model for dual-ring DLSPP designs supporting 2 × 2 thermo-optic switch operation. The validity of our circuit-level modeled 2 × 2 thermo-optic switch is verified by means of respective full vectorial three-dimensional Finite Element Method (3D-FEM) simulations. The router setup is completed by means of two 4 × 1 SOI multiplexing circuits, each one employing four cascaded second order micro-ring configurations with 100 GHz spaced resonances. Successful interconnection between the DLSPP switching matrix and the SOI circuitry is performed through a butt-coupling design that, as shown via 3D-FEM analysis, allows for small coupling losses of as low as 2.6 dB. The final router architecture is evaluated through a co-operative simulation environment, demonstrating successful 2 × 2 routing for two incoming 4-wavelength Non-Return-to-Zero (NRZ) optical packet streams with 40 Gb/s line-rates.

Si micro-ring MUX/DeMUX WDM filters

We demonstrate 3rd order micro-ring filters, 100 GHz-spaced 16 channels and 50 GHz-spaced 32 channels. Fabrication-induced resonant wavelength errors, σ = 0.237 nm, and temperature-dependent wavelength shift, 0.043 nm/°C tolerable to ΔT>10 °C, has been measured on filters based on the fundamental TM mode. The problem of CMOS-compatible photolithography is solved, while maintaining a small radius, R = 9 μm. As some dummy channels are arranged, it is shown that an on-chip optical network for many cores CPU can be constructed by 16 channel ring filters with the currently available technology.

Group delay and dispersion analysis of compound high order microring resonator all-pass filter

In this paper, we propose a novel compound high order microring resonator all-pass filter employing two cascaded microrings and an assistant microring. It improves the dispersion compensation ability and provides a wide bandwidth. The group delay range is effectively extended, which provides flexibility in choosing the geometrical parameters of the microring for technical convenience and bend loss improvement. The careful design of coupling coefficients can optimize the group delay response. This device is able to provide dispersion compensation to systems such as the high speed dense wavelength division multiplexer (DWDM) optical fiber links.