3D integration of photonic crystal devices: vertical coupling with a silicon waveguide (original) (raw)

Slow-wave effect and mode-profile matching in photonic crystal microcavities

Physical Review B, 2005

Physical mechanisms involved in the light confinement in photonic crystal slab microcavities are investigated. We first present a full three-dimensional numerical study of these microcavities. Then, to gain physical insight into the confinement mechanisms, we develop a Fabry-Perot model. This model provides accurate predictions and sheds new light on the physics of light confinement. We clearly identify two mechanisms to enhance the Q factor of these microcavities. The first one consists in improving the mode-profile matching at the cavity terminations and the second one in using a slow wave in the cavity. PACS : 42.55.Sa Microcavity and microdisk lasers 42.70.Qs Photonic bandgap materials 42.55.Tv Photonic crystal lasers 42.50.Pq Cavity quantum electrodynamics 1 Electromagnetic resonant cavities, which trap light within a finite volume, are essential components of many important optical devices and effects. Besides standard applications of these structures as lasers or frequency filters, they can potentially be used in solid-state quantum electrodynamics experiments to enhance or reduce the spontaneous emission rate 1 and in related applications to quantum information studies. 2 An ideal cavity would show infinitely narrow resonances at discrete frequencies and would confine light indefinitely.

Design of Ultrahigh- $Q$ 1-D Photonic Crystal Microcavities

IEEE Journal of Quantum Electronics, 2009

Waveguide based 1-D photonic crystal (PC) microcavities in silicon-on-insulator are investigated by 2-D finite-difference time-domain method. Values up to 6 7 10 6 for the quality factor () are feasible if the cavities are properly designed. The factors that govern are analyzed in both real space and momentum space. Etching down into the SiO 2 layer is found to give more than 20% improvement in compared to the structure in which etching is stopped at the oxide layer. Short air gap mirrors are used to reduce the vertical scattering loss. The addition to the Bragg mirrors of tapered periods optimized to produce a cavity mode with a near Gaussian shaped envelope results in a major reduction in vertical loss. A new tapered structure with varying Si block width demonstrates an ultrahigh-and relieves the fabrication constraints compared to the conventional air slots tapered structure.

Hybrid add-drop filter based on one-dimensional photonic crystal Fabry-Perot resonator

Journal of Nanophotonics, 2009

We devised an approach for realizing add-drop filters. This approach uses strip waveguides to couple light into photonic crystal based resonators. We used silicon on insulator substrate with a 240 nm thick Si layer. Theoretical analysis, simulation and experiments were conducted. We compared the new device to a ring-based add-drop filter and found that for rings with radii smaller than 1.414 µm, our device has significant advantages.

Design of tapering one-dimensional photonic crystal ultrahigh-Q microcavities

Photonics and Nanostructures - Fundamentals and Applications, 2009

One-dimensional (1D) photonic crystal (PC) microcavities can be readily embedded into silicon-on-insulator waveguides for photonic integration. Such structures are investigated by 2D Finite-Difference Time-Domain method to identify designs with high transmission which is essential for device integration. On-resonance transmission is found to decrease with the increasing mirror pairs, however, the quality factor (Q) increases to a saturated value. The addition to the Bragg mirrors of tapered periods optimized to produce a cavity mode with a near Gaussian shaped envelope results in a major reduction in vertical loss. Saturated Q up to 2.4 Â 10 6 is feasible if the internal tapers are properly designed. The effect of increasing transmission is also demonstrated in a structure with the external tapers. #

High-Q CMOS-integrated photonic crystal microcavity devices

Scientific Reports, 2014

Integrated optical resonators are necessary or beneficial in realizations of various functions in scaled photonic platforms, including filtering, modulation, and detection in classical communication systems, optical sensing, as well as addressing and control of solid state emitters for quantum technologies. Although photonic crystal (PhC) microresonators can be advantageous to the more commonly used microring devices due to the former's low mode volumes, fabrication of PhC cavities has typically relied on electron-beam lithography, which precludes integration with large-scale and reproducible CMOS fabrication. Here, we demonstrate wavelength-scale polycrystalline silicon (pSi) PhC microresonators with Qs up to 60,000 fabricated within a bulk CMOS process. Quasi-1D resonators in lateral p-i-n structures allow for resonant defect-state photodetection in all-silicon devices, exhibiting voltage-dependent quantum efficiencies in the range of a few 10 s of %, few-GHz bandwidths, and low dark currents, in devices with loaded Qs in the range of 4,300-9,300; one device, for example, exhibited a loaded Q of 4,300, 25% quantum efficiency (corresponding to a responsivity of 0.31 A/W), 3 GHz bandwidth, and 30 nA dark current at a reverse bias of 30 V. This work demonstrates the possibility for practical integration of PhC microresonators with active electro-optic capability into large-scale silicon photonic systems.

Waveguide microcavity based on photonic microstructures

IEEE Photonics Technology Letters, 2000

A waveguide based microcavity exhibiting a quality factor Q 2500 has been realized by incorporating a =4 phase shift into a 1-D photonic microstructure. The microstructure has an overall length of 3 m, consists of a deeply etched grating with very narrow (75 nm) air-gaps and exhibits a third-order stop band in the 800-900 nm wavelength regime. A comparison between measurement and simulation suggests that there is a thin (approximately 18 nm) skin of oxidized material at the etched semiconductor-air interfaces.

Optically tunable microcavity in a planar photonic crystal silicon waveguide buried in oxide

Optics Letters, 2006

We present all-optical tuning and switching of a microcavity inside a two-dimensional photonic crystal waveguide. The photonic crystal structure is fabricated in silicon-on-insulator using complementary metal-oxide semiconductor processing techniques based on deep ultraviolet lithography and is completely buried in a silicon dioxide cladding that provides protection from the environment. By focusing a laser onto the microcavity region, both a thermal and a plasma dispersion effect are generated, allowing tuning and fast modulation of the in-plane transmission. By means of the temporal characteristics of the in-plane transmission, we experimentally identify a slower thermal and a fast plasma dispersion effect with modulation bandwidths of the order of several 100 kHz and up to the gigahertz level, respectively.

Vertical microcavities based on photonic crystal mirrors for III-V/Si integrated microlasers

Photonic Crystal Materials and Devices VIII, 2008

The on-coming photonic layer of CMOS integrated circuits needs efficient light sources to treat and transmit the flow of data. We develop new configurations of III-V/Si vertical cavity lasers coupled to silicon optical waveguides using mirror/coupler based on photonic crystals. These devices can be fabricated using fully CMOS-compatible technological steps. Using this approach, the optical gain is provided by the III-V material, while all the remaining part of the optical cavity is in silicon. The output coupling to the sub-µm waveguides of the CMOS optical layer can then be inherently optimised since the laser mirror/coupler and the Si output waveguides will be realised together during the same fabrication step.