Compact Ring Resonator Research Articles

Ring resonator of surface modes based on photonic crystals

We design a compact ring resonator of surface modes based on photonic crystals (PCs). The structure is formed by sandwiching a surface mode ring waveguide (SMRW) into two parallel surface mode waveguide (SMW) based on two dimensional (2D) PCs. The SMRW is created on the surface of a circular photonic crystal (CPC) structure, where the wave propagates with high transmission efficiency. As a fundamental mode is introduced in the input SMW, at certain frequencies, the SMRW modes are enhanced because of resonance and the light-waves are coupled to the output SMW. It is demonstrated by the simulation results that the surface mode ring resonator has a low radiation loss with a very small size because of the good wave-guiding of surface mode based on PCs, and can be used in the future wavelength division multiplex (WDM) optics communication systems.

Band-pass filters using high-permittivity ceramics substrate

The miniaturization of ring band-pass filters by employing high-permittivity ceramic substrates (with respective dielectric constants of 9.7 and 23.5) are investigated. Microwave dielectric ceramics with high-permittivity are commonly applied in several microwave communication components. With the advantages of compact size, high-permittivity ceramics can be used as the substrate for band-pass filters. Moreover, the fundamental characteristics of newly developed compact ring resonators have also been described and applied to the design of band-pass filters. In this article, the designed ring resonators structures are simulated using an HFSS simulator. The responses of the fabricated band-pass filters using Al2O3 (εr = 9.7, tanδ = 0.0001) and 0.875Mg0.95Zn0.05TiO3-0.125Ca0.8Sm0.4/3TiO3 (εr = 23.5, tanδ = 0.000083) ceramic substrates are designed at the center frequency of 2.4 GHz. This compact size, low loss band-pass filter should be useful in many wireless communication systems. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2344–2347, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25439

Ultrafast All-Optical Switching in a Silicon-Nanocrystal-Based Silicon Slot Waveguide at Telecom Wavelengths

We demonstrate experimentally all-optical switching on a silicon chip at telecom wavelengths. The switching device comprises a compact ring resonator formed by horizontal silicon slot waveguides filled with highly nonlinear silicon nanocrystals in silica. When pumping at power levels about 100 mW using 10 ps pulses, more than 50% modulation depth is observed at the switch output. The switch performs about 1 order of magnitude faster than previous approaches on silicon and is fully fabricated using complementary metal oxide semiconductor technologies.

High-speed modulation of a compact silicon ring resonator based on a reverse-biased pn diode

High speed modulation based on a compact silicon ring resonator operating in depletion mode is demonstrated. The device exhibits an electrical small signal bandwidth of 19 GHz. The device is therefore a candidate for highly compact, wide bandwidth modulators for a variety of applications.

Design of a compact dual-mode ring resonator bandpass filter with harmonic suppression

An approach to suppress the harmonic responses in a dual-mode circular ring resonator bandpass filter is presented. Feed lines with one-sided coupling arms are suitably relocated around the ring resonator to introduce phase interference between two degenerate modes for simultaneously suppressing the second and third harmonics. Three open loop resonators at the rim of the ring are adopted to further suppress the second harmonic. By fabricating on a FR4 glass-epoxy base, this approach is demonstrated to have effectiveness in broadening the filter's rejection band in both simulations and measurements without affecting the fundamental response or increasing the device size.

Proposal of an OADM configuration with ultra-large FSR combining ring resonators and photonic bandgap structures

Optical Add-Drop Multiplexers (OADMs) allow extracting and inserting data channels in WDM, user access and interconnection applications. A great interest is focused on building small footprint integrated OADMs, which can be achieved using compact ring resonators (RR). Free spectral range (FSR) values up to some tens of nanometers can be obtained by using RR with small radius or multi-stage configurations, but structural parameters are pushed to the limit in these configurations leading to very tight fabrication requirements. We propose and numerically study a novel configuration of RR-based OADM where the FSR is hugely increased to values higher than 140nm by combining RRs with photonic bandgap structures, which remove the non-desired resonances inside the RR. Moreover, this structure can be hitless reconfigured, what is difficult to achieve in actual configurations.

159 W, single-frequency, continuous-wave optical parametric oscillator based on MgO:sPPLT

A watt-level, single-frequency, continuous-wave (cw) singly resonant optical parametric oscillator (OPO) based on MgO:sPPLT is described. Pumped in the green by a frequency-doubled cw diode-pumped Nd:YVO(4) laser at 532 nm, the OPO can provide up to 1.59 W of single-frequency idler output with a linewidth of ~7 MHz at pump depletions of as much as 67%. Using a compact ring resonator and optimized focusing in a 30 mm crystal, a singly resonant oscillation threshold of 2.84 W has been obtained under single-pass pumping. With a single grating period of 7.97 microm, continuous signal and idler coverage over 852-1417 nm is obtained by temperature tuning between 61 degrees C and 236 degrees C. The influence of thermal lensing on idler output power across the SRO tuning range is also verified.

Design of compact ring resonator and Mach-Zehnder interferometer with air trenches

We discuss the design of a compact ring resonator (RR) and Mach-Zehnder interferometer (MZI) in a low-refractive-index-contrast waveguide material system through the use of air trenches. A narrow air trench at the intersection of one input and two output waveguides can function as a high-efficiency splitter, while wider air trenches operate as waveguide bends. We first discuss the design of individual splitters and bends and then show how they can be used to realize a compact MZI and RR. The RR has a footprint of only 70×100 µm, and its optical efficiency at the drop wavelengths is 86%. The free spectral range and full width at half maximum are 7.2 and 0.5 nm, while the Q factor is >3,000. The MZI occupies only 165×130 µm, and its calculated optical efficiency is 90%.

Novel oscillator incorporating a compact tunable resonant cell with high efficiency and superior harmonic characteristics

This paper presents a novel microwave oscillator incorporating a simple microstrip ring-type resonant cell as its terminating resonance component. Reduced chip size, higher DC-AC power efficiency, and superior harmonic characteristics can be achieved from the introduction of this type of compact microstrip ring resonator cell. The oscillator provides a second harmonic suppression of 26.51 dB and an output power of 2.046 dBm, with 28% efficiency at an oscillation frequency of 2.11 GHz. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 413–415, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21366

Compact ring resonators using negative‐refractive‐index microstrip line

AbstractA compact ring resonator using a negative‐refractive‐index microstrip line is presented. It is demonstrated that the ring structure resonates even with an inner diameter of zero. The total circumference of the proposed resonator is reduced by 84%, as compared to a conventional ring resonator at 1.2 GHz. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 294–295, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20799

Low-Loss SOI Photonic Wires and Ring Resonators Fabricated With Deep UV Lithography

We demonstrate single-mode photonic wires in silicon-on-insulator with propagation loss as low as 2.4 dB/cm, fabricated with deep ultraviolet lithography and dry etching. We have also made compact racetrack and ring resonators functioning as add-drop filters, attaining Q values larger than 3000 and low add-drop crosstalk.

Enhanced linear and nonlinear optical phase response of AlGaAs microring resonators.

We have constructed and characterized several optical microring resonators with scale sizes of the order of 10 microm. These devices are intended to serve as building blocks for engineerable linear and nonlinear photonic media. Light is guided vertically by an epitaxially grown structure and transversely by deeply etched air-clad sidewalls. We report on the spectral phase transfer characteristics of such resonators. We also report the observation of a pi-rad Kerr nonlinear phase shift accumulated in a single compact ring resonator evidenced by all-optical switching between output ports of a resonator-enhanced Mach-Zehnder interferometer.