Near-Unity Coupling Efficiency of a Quantum Emitter to a Photonic Crystal Waveguide

The design and modeling of a curved shape photonic crystal taper consisting of Si rods integrated with a photonic crystal waveguide are presented. The waveguide is composed of a hexagonal lattice of Si rods and optimized for CO2 sensing based on absorption spectroscopy. We investigated two different approaches to design a taper for a photonic crystal waveguide in a hexagonal lattice of silicon rods. For the first approach (type 1), the taper consists of a square lattice taper followed by a lattice composed of a smooth transition from a square to a hexagonal lattice. In the second approach (type 2), the taper consists of a distorted hexagonal lattice. Different shapes, such as convex, concave, and linear, for the curvature of the taper were considered and investigated. The structure of the taper was improved to enhance the coupling efficiency up to 96% at a short taper length of 25 lattice periods. The finite-difference time-domain (FDTD) technique was used to study the transmission spectrum and the group index. The study proves the improvement of coupling using a curved shape taper. Controlling the group index along the taper could be further improved to enhance the coupling efficiency in a wider spectral range.

Download Full-text

Atom–atom interactions around the band edge of a photonic crystal waveguide

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1603788113 ◽

2016 ◽

Vol 113 (38) ◽

pp. 10507-10512 ◽

Cited By ~ 82

Author(s):

Jonathan D. Hood ◽

Akihisa Goban ◽

Ana Asenjo-Garcia ◽

Mingwu Lu ◽

Su-Peng Yu ◽

...

Keyword(s):

Photonic Crystal ◽

Quantum Optics ◽

Band Edge ◽

Single Photons ◽

Photonic Crystal Waveguide ◽

Quantum Emitter ◽

Guided Mode ◽

Low Dissipation ◽

The Cross ◽

Quantum Emitters

Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields E(x)∝e±ikxx outside the bandgap to localized fields E(x)∝e−κx|x| within the bandgap should be accompanied by a transition from largely dissipative atom–atom interactions to a regime where dispersive atom–atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the D1 line of atomic cesium for N¯=3.0±0.5 atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom–atom interactions with low dissipation into the guided mode.

Download Full-text

Photonic Crystal Tapers for Coupling Large Ridge Waveguides to Photonic Crystal Waveguides

MRS Proceedings ◽

10.1557/proc-797-w5.8 ◽

2003 ◽

Vol 797 ◽

Author(s):

Francis C. Ndi ◽

Jean Toulouse

Keyword(s):

Photonic Crystal ◽

Triangular Lattice ◽

Coupling Efficiency ◽

Ridge Waveguide ◽

Photonic Crystal Waveguide ◽

Photonic Crystal Waveguides ◽

Taper Angle ◽

Dimensional Photonic Crystal ◽

Ridge Waveguides ◽

Small Footprint

ABSTRACTWe present a study of various photonic crystal taper structures each characterized by the taper angle and roughness for coupling light into 2-dimensional photonic crystal waveguides from large ridge waveguides. The photonic crystal waveguide is made of a triangular lattice of holes in a dielectric. The objective is to find a taper structure that offers the best coupling efficiency over a range of widths of the ridge waveguide while leaving a small footprint. We show that such a structure indeed exists and can be further optimized as the width of the ridge waveguide gets even larger leading to more than 90% increase in coupling efficiency in some cases.

Download Full-text

Improved coupling efficiency by the gradual change the air holes dimensions in the photonic crystal waveguide

2013 Saudi International Electronics, Communications and Photonics Conference ◽

10.1109/siecpc.2013.6550788 ◽

2013 ◽

Author(s):

R. Naoum ◽

F. Bennacer ◽

F. Salah-Belkhodja ◽

L. Dekkiche

Keyword(s):

Photonic Crystal ◽

Coupling Efficiency ◽

Gradual Change ◽

Photonic Crystal Waveguide

Download Full-text

Subwavelength-Diameter Silica Wire and Photonic Crystal Waveguide Slow Light Coupling

Active and Passive Electronic Components ◽

10.1155/2007/78602 ◽

2007 ◽

Vol 2007 ◽

pp. 1-5 ◽

Cited By ~ 1

Author(s):

Ziyang Zhang ◽

Ulf Andersson ◽

Min Qiu

Keyword(s):

Photonic Crystal ◽

Slow Light ◽

Power Transmission ◽

Coupling Efficiency ◽

Three Dimensional ◽

Slab Waveguide ◽

Photonic Crystal Waveguide ◽

Central Wavelength ◽

Lattice Constants ◽

Light Region

Counter-directional coupling between subwavelength-diameter silica wire and single-line-defect two-dimensional photonic crystal slab waveguide is studied numerically using parallel three-dimensional finite-different time-domain method. By modifying silica wire properties or engineering photonic crystal waveguide dispersion band, the coupling central wavelength can be moved to the slow light region and the coupling efficiency improves simultaneously. One design gives 82% peak power transmission from silica wire to photonic crystal waveguide over an interacting distance of 50 lattice constants. The group velocity is estimated as 1/35 of light speed in vacuum.

Download Full-text

Design and Analysis of 2D Photonic Crystal Waveguides for High Coupling Efficiency

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.31.27 ◽

2007 ◽

Vol 31 ◽

pp. 27-29

Author(s):

Ming Wu ◽

Hai Rong Liu ◽

Wei Jun Tong ◽

De Xiu Huang

Keyword(s):

Photonic Crystal ◽

Time Domain ◽

Finite Difference Time Domain ◽

Dielectric Waveguide ◽

Fdtd Method ◽

Coupling Efficiency ◽

Photonic Crystal Waveguide ◽

Photonic Crystal Waveguides ◽

Simulation Results ◽

Difference Time

In this paper we have proposed a photonic crystal structure to enhance the coupling efficiency between photonic crystal waveguide (PCW) and the conventional dielectric waveguide. The proposed waveguide characterized with employing the taper structure and varying the holes’ radius in the taper. Two-dimensional (2D) finite-difference time-domain (FDTD) method has been used to analyze the structure. The simulation results show that the coupling efficiency can be achieved as high as 81.6% at the wavelength of 1.55um.

Download Full-text

Double-layer graphene on photonic crystal waveguide electro-absorption modulator with 12 GHz bandwidth

Nanophotonics ◽

10.1515/nanoph-2019-0381 ◽

2019 ◽

Vol 9 (8) ◽

pp. 2377-2385 ◽

Cited By ~ 4

Author(s):

Zhao Cheng ◽

Xiaolong Zhu ◽

Michael Galili ◽

Lars Hagedorn Frandsen ◽

Hao Hu ◽

...

Keyword(s):

Photonic Crystal ◽

Double Layer ◽

Slow Light ◽

Modulation Depth ◽

Photonic Crystal Waveguide ◽

Optical Modulators ◽

Layer Graphene ◽

Silicon Photonic ◽

On Chip ◽

Silicon Based

AbstractGraphene has been widely used in silicon-based optical modulators for its ultra-broadband light absorption and ultrafast optoelectronic response. By incorporating graphene and slow-light silicon photonic crystal waveguide (PhCW), here we propose and experimentally demonstrate a unique double-layer graphene electro-absorption modulator in telecommunication applications. The modulator exhibits a modulation depth of 0.5 dB/μm with a bandwidth of 13.6 GHz, while graphene coverage length is only 1.2 μm in simulations. We also fabricated the graphene modulator on silicon platform, and the device achieved a modulation bandwidth at 12 GHz. The proposed graphene-PhCW modulator may have potentials in the applications of on-chip interconnections.

Download Full-text

Towards lab-on-chip ultrasensitive ethanol detection using photonic crystal waveguide operating in the mid infrared

Nanophotonics ◽

10.1515/nanoph-2020-0576 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ali Rostamian ◽

Ehsan Madadi-Kandjani ◽

Hamed Dalir ◽

Volker J. Sorger ◽

Ray T. Chen

Keyword(s):

Photonic Crystal ◽

Slow Light ◽

High Sensitivity ◽

Guided Wave ◽

Silicon On Insulator ◽

Group Index ◽

Photonic Crystal Waveguide ◽

Mid Infrared ◽

Lab On Chip ◽

On Chip

Abstract Thanks to the unique molecular fingerprints in the mid-infrared spectral region, absorption spectroscopy in this regime has attracted widespread attention in recent years. Contrary to commercially available infrared spectrometers, which are limited by being bulky and cost-intensive, laboratory-on-chip infrared spectrometers can offer sensor advancements including raw sensing performance in addition to use such as enhanced portability. Several platforms have been proposed in the past for on-chip ethanol detection. However, selective sensing with high sensitivity at room temperature has remained a challenge. Here, we experimentally demonstrate an on-chip ethyl alcohol sensor based on a holey photonic crystal waveguide on silicon on insulator-based photonics sensing platform offering an enhanced photoabsorption thus improving sensitivity. This is achieved by designing and engineering an optical slow-light mode with a high group-index of n g = 73 and a strong localization of modal power in analyte, enabled by the photonic crystal waveguide structure. This approach includes a codesign paradigm that uniquely features an increased effective path length traversed by the guided wave through the to-be-sensed gas analyte. This PIC-based lab-on-chip sensor is exemplary, spectrally designed to operate at the center wavelength of 3.4 μm to match the peak absorbance for ethanol. However, the slow-light enhancement concept is universal offering to cover a wide design-window and spectral ranges towards sensing a plurality of gas species. Using the holey photonic crystal waveguide, we demonstrate the capability of achieving parts per billion levels of gas detection precision. High sensitivity combined with tailorable spectral range along with a compact form-factor enables a new class of portable photonic sensor platforms when combined with integrated with quantum cascade laser and detectors.

Download Full-text