An overview is presented of the current state-of-the-art in silicon nanophotonic ring resonators. Basic theory of ring resonators is discussed, and applied to the peculiarities of submicron silicon photonic wire waveguides: the small dimensions and tight bend radii, sensitivity to perturbations and the boundary conditions of the fabrication processes. Theory is compared to quantitative measurements. Finally, several of the more promising applications of silicon ring resonators are discussed: filters and optical delay lines, label-free biosensors, and active rings for efficient modulators and even light sources.

/pdf/silicon-microring-resonators-3fzr4lpxbh.pdf

Silicon microring resonators

The nonlinearities in silicon are diverse. This Review covers the wealth of nonlinear effects in silicon and highlights the important applications and technological solutions in nonlinear silicon photonics. The increasing capability for manufacturing a wide variety of optoelectronic devices from polymer and polymer–silicon hybrids, including transmission fibre, modulators, detectors and light sources, suggests that organic photonics has a promising future in communications and other applications.

Nonlinear silicon photonics

Silicon lasers have long been a goal for semiconductor scientists, and a number of important breakthroughs in the past decade have focused attention on silicon as a photonic platform. Here we review the most recent progress in this field, including low-threshold silicon Raman lasers with racetrack ring resonator cavities, the first germanium-on-silicon lasers operating at room temperature, and hybrid silicon microring and microdisk lasers. The fundamentals of carrier transition physics in crystalline silicon are discussed briefly. The basics of several important approaches for creating lasers on silicon are explained, and the challenges and opportunities associated with these approaches are discussed. Silicon lasers have long been a goal for semiconductor scientists. This Progress Article reviews the most recent developments in this field, including silicon Raman lasers, the first germanium-on-silicon lasers operating at room temperature, and hybrid silicon microring and microdisk lasers. Challenges and opportunities for the present approaches are also discussed.

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Recent progress in lasers on silicon

Integrated optical circuits based on silicon-on-insulator technology are likely to become the mainstay of the photonics industry. Over recent years an impressive range of silicon-on-insulator devices has been realized, including waveguides1,2, filters3,4 and photonic-crystal devices5. However, silicon-based all-optical switching is still challenging owing to the slow dynamics of two-photon generated free carriers. Here we show that silicon–organic hybrid integration overcomes such intrinsic limitations by combining the best of two worlds, using mature CMOS processing to fabricate the waveguide, and molecular beam deposition to cover it with organic molecules that efficiently mediate all-optical interaction without introducing significant absorption. We fabricate a 4-mm-long silicon–organic hybrid waveguide with a record nonlinearity coefficient of γ ≈ 1 × 105 W−1 km−1 and perform all-optical demultiplexing of 170.8 Gb s−1 to 42.7 Gb s−1. This is—to the best of our knowledge—the fastest silicon photonic optical signal processing demonstrated. A silicon–organic hybrid slot waveguide with a strong optical nonlinearity is demonstrated to perform ultrafast all-optical demultiplexing of high-bit-rate data streams. The approach could form the basis of compact high-speed optical processing units for future communication networks.

/pdf/all-optical-high-speed-signal-processing-with-silicon-2nxlva6l54.pdf

All-optical high-speed signal processing with silicon–organic hybrid slot waveguides

In this paper III-V on silicon-on-insulator (SOI) het- erogeneous integration is reviewed for the realization of near infrared light sources on a silicon waveguide platform, suitable for inter-chip and intra-chip optical interconnects. Two bonding technologies are used to realize the III-V/SOI integration: one based on molecular wafer bonding and the other based on DVS- BCB adhesive wafer bonding. The realization of micro-disk lasers, Fabry-Perot lasers, DFB lasers, DBR lasers and mode- locked lasers on the III-V/SOI material platform is discussed. Artist impression of a multi-wavelength laser based on micro- disk cavities realized on a III-V/SOI heterogeneous platform and a microscope image of a realized structure.

III‐V/silicon photonics for on‐chip and intra‐chip optical interconnects

A compact, electrically driven light source integrated on silicon is a key component for large-scale integration of electronic and photonic integrated circuits. Here we demonstrate electrically injected continuous-wave lasing in InP-based microdisk lasers coupled to a sub-micron silicon wire waveguide, fabricated through heterogeneous integration of InP on silicon-on-insulator (SOI). The InP-based microdisk has a diameter of 7.5 mum and a thickness of 1 mum. A tunnel junction was incorporated to efficiently contact the p-side of the pn-junction. The laser emits at 1.6 mum, with a threshold current as low as 0.5 mA under continuous-wave operation at room temperature, and a threshold voltage of 1.65 V. The SOI-coupled laser slope efficiency was estimated to be 30 muW/mA, with a maximum unidirectional output power of 10 muW.

http://pcphotonics.intec.ugent.be/download/pub_2116.pdf

Electrically pumped InP-based microdisk lasers integrated with a nanophotonic silicon-on-insulator waveguide circuit.

We present an InP-based membrane p-i-n photodetector on a silicon-on-insulator sample containing a Si-wiring photonic circuit that is suitable for use in optical interconnections on Si integrated circuits (ICs). The detector mesa footprint is 50 μm2, which is the smallest reported to date for this kind of device, and the junction capacitance is below 10 fF, which allows for high integration density and low dynamic power consumption. The measured detector responsivity and 3-dB bandwidth are 0.45 A/W and 33 GHz, respectively. The device fabrication is compatible with wafer-scale processing steps, guaranteeing compatibility toward future-generation electronic IC processing.

/pdf/inp-ingaas-photodetector-on-soi-photonic-circuitry-1xq7lmc8f4.pdf

InP/InGaAs Photodetector on SOI Photonic Circuitry

We propose and demonstrate a photonic interconnect layer consisting of heterogeneous microdisk lasers and microdetectors integrated with a nanophotonic silicon waveguide circuit. The photonic layer is fabricated using waferscale processes and a die-to-wafer molecular bonding process.

/pdf/a-photonic-interconnect-layer-on-cmos-1egluiaie4.pdf

A photonic interconnect layer on CMOS

We present the design, fabrication and characterization of an InP-based membrane photodetector on an SOI wafer containing a Si-wiring photonic circuit. Measured detector responsivity and 3 dB bandwidth are 0.45 A/W and 33 GHz, respectively. The photonic device fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic IC processing.

/pdf/inp-ingaas-photodetector-on-soi-circuitry-h6tbudh5lq.pdf

InP/InGaAs photodetector on SOI circuitry

We present the design, fabrication, and characterization of a membrane coupler processed on an indium phosphide membrane layer on a silicon-on-insulator wafer, that is used for applications in optical interconnects on silicon. Measured coupler efficiency is 50%. The photonic device fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic integrated circuit processing.

C Lagahe

Papers

Electrically pumped InP-based microdisk lasers integrated with a nanophotonic silicon-on-insulator waveguide circuit.

InP/InGaAs Photodetector on SOI Photonic Circuitry

A photonic interconnect layer on CMOS

InP/InGaAs photodetector on SOI circuitry

InP-Based Membrane Couplers for Optical Interconnects on Si