We present a high-efficiency silicon optical switch utilizing a silicon-GSST hybrid integrated waveguide. Optical wave propagating in the hybrid waveguide is modulated through the phase change of GSST. This phase change is triggered by electro-thermal heating from a PIN diode located beneath the GSST strip. We employ the hybrid integrated waveguide as a phase shifter and incorporate a Mach-Zehnder Interferometer (MZI) structure to serve as an optical switch. The device supports over 1000 effective switching events. Additionally, multi-level switching is achieved on a single waveguide, offering 128 non-volatile transmission levels. Our research indicates significant potential applications in optical switching, computing, and storage.
We demonstrate a high-efficiency silicon optical phase shifter based on a silicon-Sb2Se3 hybrid integrated waveguide. The optical field has large confinement in the Sb2Se3 material, leading to high optical wave modulation efficiency upon phase change of Sb2Se3. The phase change is initiated by electro-thermal heating generated by a highly durable graphene microheater positioned between the Sb2Se3 strip and the silicon slab of the hybrid waveguide. To effectively couple the phase shifter with single-mode silicon waveguides, we design a two-layer taper structure as a mode spot size converter. Utilizing this phase shifter, we implemented a Mach–Zehnder interferometer structure to function as an optical switch. The number of effective switching events exceeds 30,000, and 66 non-volatile switching levels are obtained. Our work provides an effective solution for introducing highly durable graphene microheaters on silicon-based phase-change platforms.
In this paper, we demonstrate a reconfigurable device that could realize modulation on TE0 polarization or TM0 polarization selectively. The device consists of a pair of TM0-TE1/TE1-TM0 mode converters, two TE0-TE1 mode exchangers, and a TE1 mode micro-ring modulator. 32 Gb/s on-off keying modulation is successfully demonstrated both for TE0 polarization and TM0 polarization.
Soliton microcombs, relying on the double balance of dispersion and nonlinearity, as well as gain and cavity loss, are formed in the mode-locked regime of a high-quality micro-resonator. Various soliton microcomb states can provide frequency components with different repetition rates and power, satisfying a variety of applications. Programmable switching of the soliton states increases operational flexibility. Here, we report the programmable switching of soliton microcomb states in a Si3N4 micro-resonator with anomalous dispersion by using an auxiliary laser. Red-detuned pump entrance is implemented to support the reliable judgement of state switching. Single-soliton state was realized in a small frequency tuning range of the auxiliary laser while multi-soliton states can be achieved under a wide range. The achievable soliton state number is related to the relative frequency position of the auxiliary laser. We can realize more number of the soliton states when the auxiliary laser is in the middle of the tuning range.
We present a programmable universal Si3N4 optical filter that can be reconfigured to various filter functions. The basic compositive structure is the Mach-Zehnder interferometer (MZI) with each arm coupled with a ring resonator. The input and output couplers in the MZI and the ring couplers are all tunable with coupling ratio varying from zero to one, making the device highly flexible. We theoretically investigate six configurations using the transfer function, revealing that the device can produce versatile filtering shape. Experimental demonstration of three configurations agree with the theoretical prediction. With a careful control of the ring coupling ratio, the filter can successfully generate sub-GHz passband that allows for high spectral-resolution microwave signal processing.
A novel silicon reconfigurable optical processor (SROP) is proposed based on a self-coupled optical waveguide (SCOW) resonant architecture. The SCOW is formed by a single meandering waveguide self-coupled to form directional couplers at the input and output ends. The SROP consists of three-stages of SCOW resonators, where the directional couplers are replaced by Mach-Zehnder interferometers (MZIs) to work as tunable couplers. Both phase shifters and variable optical attenuators (VOAs) are integrated in the device for active phase and amplitude tuning, respectively. By reconfiguring the states of tunable couplers, phase shifters and VOAs, the SROP is implemented as ring resonator, MZI, and Fabry-Perot cavity-based optical structures for versatile optical processing applications.
We report our recent progress on high-throughput 16×16 silicon non-blocking optical switches based on Mach- Zehnder interferometers (MZIs) and dual-ring assisted MZIs (DR-MZIs). TiN microheaters and p-i-n diodes are both integrated in each switch element for thermo-optic phase error correction and GHz-speed electro-optic switching, respectively. The MZI switch exhibits a broad optical bandwidth and low crosstalk. The DR-MZI switch exhibits low electrical switching power but with a narrower optical bandwidth. The two types of switches are designed to have a chip size of 12.1 mm × 4.6 mm mainly restricted by the chip package requirement. The DR-MZI chip can potentially have a smaller footprint due to its much more compact switch element, suitable for high-density on-chip optical data exchange.
We report our recent progress on reconfigurable optical true time delay lines (RTTDL) and optical switches. The
RTTDL is composed of 8 stages of MZIs connected by 7 waveguide pairs with an incremental length difference.
Variable optical attenuators are inserted in the delay waveguides to suppress crosstalk caused by the residual signals
from noise paths. Transmission of a 25 Gbps PRBS signal confirms the signal fidelity after a maximum of 1.27 ns
delay. The optical switch is based on a Benes architecture with Mach-Zehnder interferometers (MZI) as the
switching elements. Both p-i-n diodes and silicon resistive micro-heaters are integrated in the MZI arms for
electrical tuning and phase correction, respectively. The measured on-chip insertion loss of the 4×4 switch is < 8 dB.
Transmission of a 50 Gb/s quadrature phase shift keying (QPSK) optical signal verifies its switching functionality.
We present our recent work on integrated silicon photonic devices for optical filter and delay applications. A microdisk
resonator integrated with interleaved p-n junctions is demonstrated. The resonance can be both blue- and red-shifted by applying a forward current or a negative voltage, respectively. A MZI-nested microring resonator is shown capable of
coupling tuning, enabled by a p-i-p junction based thermal heater across the waveguide. We also investigate cascaded
self-coupled optical waveguide (SCOW) resonators. Electromagnetically-induced transparency (EIT)-like resonances are
generated featuring a narrow lineshape and a high group delay. Finally, we present an athermal lattice filter made up of 10 cascaded Mach-Zehnder interferometer (MZI) units and show that the temperature sensitivity can be considerably
reduced.
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