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

Integrated Bragg gratings in spiral waveguides

Alexandre D. Simard, Yves Painchaud, and Sophie LaRochelle

Open Access Open Access

Abstract

Over the last two decades, many filters requiring custom spectral responses were obtained from photo-inscribed fiber Bragg gratings because of the flexibility inherent to this technology. However, Bragg gratings in silicon waveguides have the potential to provide faster and more efficient tuning capabilities when compared to optical fiber devices. One drawback is that Bragg gratings filters with elaborate spectral amplitude and phase responses often require a long interaction length, which is not compatible with current integration trends in CMOS compatible photonic circuits. In this paper, we propose to make Bragg gratings in spiral-shaped waveguides in order to increase their lengths while making them more compact. The approach preserves the flexibility of regular straight grating structures. More specifically, we demonstrate 2-mm long gratings wrapped in an area of 200 µm x 190 µm without any spectral degradation due to waveguide curvature. Furthermore, we interleave three spiral waveguides with integrated gratings thereby tripling the density and demonstrate good phase compensation for each of them. Finally, we show that this approach is compatible with phase-apodization of the grating coupling coefficient.

©2013 Optical Society of America

Full Article  |  PDF Article
More Like This
Characterization and reduction of spectral distortions in Silicon-on-Insulator integrated Bragg gratings

Alexandre D. Simard, Guillaume Beaudin, Vincent Aimez, Yves Painchaud, and Sophie LaRochelle
Opt. Express 21(20) 23145-23159 (2013)

Characterization and compensation of apodization phase noise in silicon integrated Bragg gratings

Rui Cheng, Ya Han, and Lukas Chrostowski
Opt. Express 27(7) 9516-9535 (2019)

Tunable spiral Bragg gratings in 60-nm-thick silicon-on-insulator strip waveguides

Zhi Zou, Linjie Zhou, Minjuan Wang, Kan Wu, and Jianping Chen
Opt. Express 24(12) 12831-12839 (2016)

View More...

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 (6)
Fig. 1
Fig. 1 (a) Three different schematic of spiral gratings; (b) CAD mask of the spiral IBGs used in this paper; (c) Optical microscope image of the first spiral-IBG row.

Download Full Size | PDF

Fig. 2
Fig. 2 (a) Radius of curvature of the spirals shown in Fig. 1(a); (b) Variation of the effective index of a 1200 nm x 220 nm passivated silicon waveguide as function of its radius of curvature; (c) Phase function that must be incorporated in the grating structure to compensate the effective index variation caused by the curvature of the spirals shown in Fig. 1(a). (d) The resulting grating period. The dotted black line is the uncorrected grating period.

Download Full Size | PDF

Fig. 3
Fig. 3 (a) Comparison of the experimental reflection spectrum of an uncompensated spiral IBG (in red) with the reconstructed reflection spectrum (in black) and the designed uniform grating response (blue curve). Retrieved (b) λB and (c) Δn profiles, which are used to calculate the black curve of (a).

Download Full Size | PDF

Fig. 4
Fig. 4 (a) Comparison of the experimental reflection spectrum of a phase compensated spiral IBG (in red) with the reconstructed reflection spectrum (in black) and the designed uniform grating response (blue curve). Retrieved (b) λB and (c) Δn profiles, which are used to calculate the black curve of (a).

Download Full Size | PDF

Fig. 5
Fig. 5 (a) Interleaved spiral having R0 = 59 µm, Δw = 15 µm and α = 0.671 and a minimal radius of curvature of 20 µm for the blue and red waveguides and 25 µm for the black (central) waveguide. (b) Radius of curvature of a typical interleaved spiral as function of the position on the spiral waveguide. (c) Phase function that must be incorporated in the grating structure to compensate the effective index variation caused by the curvature. (d) Comparison of the experimental reflection spectrum of a compensated interleaved spiral IBG (in red) with the reconstructed reflection spectrum (in black) and the designed uniform grating response (blue curve). Retrieved (e) λB and (f) Δn profiles, which are used to calculate the black curve of (d).

Download Full Size | PDF

Fig. 6
Fig. 6 (a) Comparison of the experimental reflection spectrum of a compensated Gaussian-apodized CBG (in red) with the reconstructed reflection spectrum (in black). The blue curve is the spectrum obtained with the ideal Gaussian apodization profile shown in (c) and an ideal Bragg wavelength while the green curve is the spectrum calculated with the noisy apodization profile but without phase noise (ideal Bragg wavelength). Retrieved (b) λB and (c) Δn profiles, which are used to calculate the black curve of (a).

Download Full Size | PDF

Equations (7)

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

S=R(ρ) e i| ρ | −Δx
R(ρ)= R 0 sgn(ρ)+ Δwρ /π
Δx= R 0 sgn(ρ) e −| ρ |/α
n(z)=n(λ)+δn( R(z) )+Δncos( 2π Λ z+θ(z)+Ω(z) )
Ω(z)= 2π nΛ ∫ −L/2 z dz'δn( R(z') ) .
Λ( z )= Λ [ 1+ Λ 2π ∂θ(z) ∂z + Λ 2π ∂Ω(z) ∂z ]
Δncos( 2π Λ z+θ(z)+Ω(z)+ϕ(z)sin( 2π Λ M z ) ).
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