Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
Journal Home About Issues in Progress Current Issue All Issues Feature Issues

Wideband and low dispersion slow light by chirped photonic crystal coupled waveguide

Daisuke Mori and Toshihiko Baba

Open Access Open Access

Abstract

Previously, we discussed an optical delay device consisting of a directional coupler of two different photonic crystal (PC) waveguides. It generates wideband and low dispersion slow light. However, it is easily degraded by a large reflection loss for a small imperfection of the coupling condition. In this paper, we propose and theoretically discuss a PC coupled waveguide, which allows more robust slow light with lower loss. For this device, unique photonic bands with a zero or negative group velocity at the inflection point can be designed by the structural tuning. Finite difference time domain simulation demonstrates the stopping and/or back and forth motion of an ultrashort optical pulse in the device combined with the chirped structure. For a signal bandwidth of 40 GHz, the average group index of the slow light will be 450, which gives a 1 ns delay for a device length of 670 μm. The theoretical total insertion loss at the device and input/output structures is as low as 0.11 dB.

©2005 Optical Society of America

Full Article  |  PDF Article
More Like This
Wideband slow light in chirped slot photonic-crystal coupled waveguides

Jin Hou, Huaming Wu, D. S. Citrin, Wenqin Mo, Dingshan Gao, and Zhiping Zhou
Opt. Express 18(10) 10567-10580 (2010)

Experimental observation of slow light in photonic crystal coupled waveguides

Takashi Kawasaki, Daisuke Mori, and Toshihiko Baba
Opt. Express 15(16) 10274-10281 (2007)

Experimental demonstration of wideband dispersion-compensated slow light by a chirped photonic crystal directional coupler

Daisuke Mori, Shousaku Kubo, Hirokazu Sasaki, and Toshihiko Baba
Opt. Express 15(9) 5264-5270 (2007)

View More...

Supplementary Material (2)

Media 1: MOV (2387 KB)     
Media 2: MOV (2353 KB)     

Cited By

Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (10)
Fig. 1.
Fig. 1. Schematic of ideal band shifted by chirping against the frequency of incident light (dashed line).

Download Full Size | PDF

Fig. 2.
Fig. 2. Schematic of PC directional coupler with coupled mode profiles and corresponding bands.

Download Full Size | PDF

Fig. 3.
Fig. 3. Real structures of PC coupled waveguides and corresponding bands. Thick and thin lines indicate bands of the even mode and other modes, respectively. Light gray and dark gray regions show the light cone above the air light line and slab mode regions, respectively. For the band of (a), airhole shift d is set to be 0.25a.

Download Full Size | PDF

Fig. 4.
Fig. 4. Dependence of band for the structure of Fig. 3(a) on background index n, where d = 0.25a is assumed.

Download Full Size | PDF

Fig. 5.
Fig. 5. Dependence of band for the structure of Fig. 3(a) on airhole shift d, where n = 2.963 is assumed.

Download Full Size | PDF

Fig. 6.
Fig. 6. Light intensity profile for each time frame and pulse waveforms of light power toward the right side. (a) and (b) are those for structures of Fig. 3(a) with d = 0.25a and 0.10a, respectively. Line in each figure shows corresponding photonic band. Animations show the light propagation (Hz field) for each structure, where red, yellow, green, light blue and dark blue show intensities from plus to minus. [Media 1] [Media 2]

Download Full Size | PDF

Fig. 7.
Fig. 7. Schematic band diagram in the repeated zone scheme for the explanation of back and forth motion in Fig. 6(b).

Download Full Size | PDF

Fig. 8.
Fig. 8. Upper limit values of n͂g and n͂g ∆ωs/ω for bands of Fig. 5 calculated with ∆ωs/ω, where d is used as a parameter.

Download Full Size | PDF

Fig. 9.
Fig. 9. I/O structure for the structure of Fig. 3(a) with photonic wire waveguides. (a) Half elliptical taper used with bend waveguide type branch. (b) Half circular funnel taper as a confluence.

Download Full Size | PDF

Fig. 10.
Fig. 10. I/O structure for the structure of Fig. 3(a) with PC single line defect waveguides. (a) Branch. (b) Confluence.

Download Full Size | PDF

Equations (5)

Equations on this page are rendered with MathJax. Learn more.

Δ T = ∫ 0 Δ L d x υ g ( x ) = ∫ 0 Δ L n g ( x ) c d x .
n ͂ g = c υ ͂ g = c Δ L Δ T = ∫ 0 Δ L n g ( x ) d x Δ L .
n ͂ g ≅ ∫ ω 0 ω 0 + Δ ω n g ( ω ) d ω / Δ ω = ∫ ω 0 ω 0 + Δ ω c d k d ω d ω / Δ ω = ∫ k 0 k 0 + Δ k c d k / Δ ω = c Δ k Δ ω
n ͂ g Δ ω s ω ≤ n ͂ g Δ ω 2 ω = Δ k 2 k .
n ͂ g Δ ω s ω ≤ n ͂ g Δ ω − Δ ω p 2 ω = Δ k 2 k ( 1 − Δ ω p Δ ω )
Select as filters
Select Topics Cancel
Top
       
© Copyright 2024 | Optica Publishing Group. All rights reserved, including rights for text and data mining and training of artificial technologies or similar technologies.
Privacy | Terms of Use