On the role of evanescent modes and group index tapering in slow light photonic crystal waveguide coupling efficiency

2011 ◽  
Vol 98 (3) ◽  
pp. 031107 ◽  
Author(s):  
Amir Hosseini ◽  
Xiaochuan Xu ◽  
David N. Kwong ◽  
Harish Subbaraman ◽  
Wei Jiang ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Slow Light ◽  
Coupling Efficiency ◽  
Group Index ◽  
Photonic Crystal Waveguide ◽  
Waveguide Coupling

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

Nanophotonics ◽  
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.

Experiments with Phase-Delay and Time-Delay Methods for Slow Light in Photonic Crystal Waveguide

2013 ◽  
Vol 684 ◽  
pp. 290-294
Author(s):  
Hui Lu ◽  
Li Jun Zhang ◽  
Zhan Qi Zheng ◽  
Yi Heng Zhang ◽  
Yong Qing Leng
Keyword(s):  
Photonic Crystal ◽  
Time Delay ◽  
Theoretical Result ◽  
Slow Light ◽  
Phase Delay ◽  
Silicon On Insulator ◽  
Group Index ◽  
Experimental Measurements ◽  
Photonic Crystal Waveguide ◽  
Good Agreement

In this paper, we report the experimental measurements of the group index of a photonic crystal waveguide based on silicon-on-insulator slab. The time-delay of the pulse is also measured, and it is in good agreement with the theoretical result calculated according to the group index with the phase-delay method, which is about 4.7ps.

scholarly journals Design of a Curved Shape Photonic Crystal Taper for Highly Efficient Mode Coupling

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 585
Author(s):  
Reyhaneh Jannesari ◽  
Thomas Grille ◽  
Cristina Consani ◽  
Gerald Stocker ◽  
Andreas Tortschanoff ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Hexagonal Lattice ◽  
Coupling Efficiency ◽  
Smooth Transition ◽  
Square Lattice ◽  
Group Index ◽  
Photonic Crystal Waveguide ◽  
Silicon Rods

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.

scholarly journals Slow Light Tuning in Annular Slotted Photonic Crystal Waveguide with Incoming Polymer

2021 ◽  
Vol 2109 (1) ◽  
pp. 012008
Author(s):  
Konttao Zhu ◽  
Hongxue Yang ◽  
Hui Du
Keyword(s):  
Photonic Crystal ◽  
Group Velocity ◽  
Slow Light ◽  
Transmission Rate ◽  
Group Velocity Dispersion ◽  
Flat Band ◽  
Group Index ◽  
Photonic Crystal Waveguide ◽  
Processing Scheme ◽  
Operating Wavelength

Abstract An advanced post-processing scheme of reconfigurable dielectric infiltration into an annular slotted photonic crystal waveguide (ASPhCW) is proposed in this paper. Ionic liquids have had prominent effects in enhancing the optical properties of photonic crystals, especially in the aspect of tuning the transmission rate and velocity through optical materials. Using the two-dimensional plane wave expansion method, the flat band dispersion of the slow light is obtained and the tuning of the operating wavelength of the crystal could be realized by incoming polymer technology. The operating wavelength tuning range could be as large as 459.27nm and the group index could be tuned as high as 44.8 with a near zero group velocity dispersion. Using this method, a high group index equaling 45 with the bandwidth equaling 11.3nm and the normalized delay bandwidth product (NDBP) equaling 0.25 is realized. This incoming polymer technology provides an effective method of getting flat band of slow light flexibly and makes it possible to offer longer delay and low group velocity after fabrication.

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