Topologically protected transport has recently emerged as an effective means to address a recurring problem hampering the field of slow light for the past two decades: its keen sensitivity to disorders and structural imperfections. With it, there has been renewed interest in efforts to overcome the delay-time-bandwidth limitation usually characterizing slow-light devices, on occasion thought to be a fundamental limit. What exactly is this limit, and what does it imply? Can it be overcome? If yes, how could topological slow light help, and in what systems? What applications might be expected by overcoming the limit? Our Perspective here attempts addressing these and other related questions while pointing to important new functionalities both for classical and quantum devices that overcoming the limit can enable.

1.
K. J.
Vahala
,
Optical Microcavities
(
World Scientific
,
2005
).
2.
L.
Novotny
and
B.
Hecht
,
Principles of Nano-Optics
(
Cambridge University Press
,
2012
).
3.
H. A.
Haus
,
Waves and Fields in Optoelectronics
(
Prentice-Hall
,
1984
).
4.
D. M.
Pozar
,
Microwave Engineering
(
Wiley
,
2011
).
5.
Simply silicon
,
Nat. Photonics
4
,
491
(
2010
).
6.
G. T.
Reed
,
Silicon Photonics: The State of the Art
(
Wiley
,
2008
).
7.
S. M.
Dutra
,
Cavity Quantum Electrodynamics: The Strange Theory of Light in a Box
(
Wiley
,
2005
).
8.
J. B.
Pendry
,
A. J.
Holden
,
D. J.
Robbins
et al, “
Magnetism from conductors and enhanced nonlinear phenomena
,”
IEEE Trans. Microwave Theory Technol.
47
,
2075
(
1999
).
9.
K. L.
Tsakmakidis
,
L.
Shen
,
S. A.
Schulz
,
X.
Zheng
,
J.
Upham
,
X.
Deng
,
H.
Altug
,
A. F.
Vakakis
, and
R. W.
Boyd
, “
Breaking Lorentz reciprocity to overcome the time-bandwidth limit in physics and engineering
,”
Science
356
,
1260
(
2017
).
10.
K. L.
Tsakmakidis
,
Y.
You
,
T.
Stefański
, and
L.
Shen
, “
Nonreciprocal cavities and the time-bandwidth limit: Comment
,”
Optica
7
,
1097
1101
(
2020
).
11.
R. S.
Tucker
,
P.-C.
Ku
, and
C. J.
Chang-Hasnain
, “
Slow-light optical buffers: Capabilities and fundamental limitations
,”
J. Lightwave Technol.
23
,
4046
4066
(
2005
).
12.
J. B.
Khurgin
, “
Bandwidth limitation in slow light schemes
,” in
Slow Light: Science and Applications
, edited by
J. B.
Khurgin
and
R. S.
Tucker
(
Taylor & Francis Group
,
2008
), Chap. 15, pp.
293
320
.
13.
D. A. B.
Miller
, “
Fundamental limit to linear one-dimensional slow light structures
,”
Phys. Rev. Lett.
99
,
203903
(
2007
).
14.
K. J.
Vahala
, “
Optical microcavities
,”
Nature
424
,
839
846
(
2003
).
15.
H.
Lee
,
T.
Chen
,
J.
Li
,
K. Y.
Yang
,
S.
Jeon
,
O.
Painter
, and
K. J.
Vahala
, “
Chemically etched ultrahigh-Q wedge-resonator on a silicon chip
,”
Nat. Photonics
6
,
369
373
(
2012
).
16.
H. A.
Haus
,
Electromagnetic Noise and Quantum Optical Measurements
(
Springer
,
Berlin/Heidelberg
,
2000
).
17.
K.
Baskourelos
,
O.
Tsilipakos
,
T.
Stefański
et al, “
Topological microscopy and near-perfect optical extraordinary transmission
,” arXiv:2105.12280 (
2021
).
18.
E.
Mohammadi
,
K. L.
Tsakmakidis
,
A. N.
Askarpour
et al, “
Nanophotonic platforms for enhanced chiral sensing
,”
ACS Photonics
5
,
2669
2675
(
2018
).
19.
E.
Mohammadi
,
A.
Tavakoli
,
P.
Dehkhoda
et al, “
Accessible superchiral near-fields driven by tailored electric and magnetic resonances in all-dielectric nanostructures
,”
ACS Photonics
6
,
1939
1946
(
2019
).
20.
E.
Mohammadi
,
A.
Tittl
,
K. L.
Tsakmakidis
et al, “
Dual nanoresonators for ultrasensitive chiral detection
,”
ACS Photonics
8
,
1754
(
2021
).
21.
K. L.
Tsakmakidis
,
O.
Hess
,
R. W.
Boyd
, and
X.
Zhang
, “
Ultraslow waves on the nanoscale
,”
Science
358
,
eaan5196
(
2017
).
22.
A.
Mojahed
,
K. L.
Tsakmakidis
,
L. A.
Bergman
et al, “
Exceeding the classical time-bandwidth product in nonlinear time-invariant systems
,” arXiv:2106.06814 (
2021
).
23.
I.
Cardea
,
D.
Grassani
,
J.
Upham
et al, “
Unconventional time-bandwidth performance of resonant cavities with nonreciprocal coupling
,”
Phys. Rev. A
103
,
013716
(
2021
).
24.
W. T.
Lu
and
S.
Sridhar
, “
Slow light, open-cavity formation, and large longitudinal electric field on a slab waveguide made of indefinite permittivity metamaterials
,”
Phys. Rev. A
82
,
013811
(
2010
).
25.
D. A.
Genov
,
S.
Zhang
, and
X.
Zhang
, “
Mimicking celestial mechanics in metamaterials
,”
Nat. Phys.
5
,
687
(
2009
).
26.
D. E.
Fernandes
and
M. G.
Silveirinha
, “
Topological origin of electromagnetic energy sinks
,”
Phys. Rev. Appl.
12
,
014021
(
2019
).
27.
K.
Liu
and
S.
He
, “
Truly trapped rainbow by utilizing nonreciprocal waveguides
,”
Sci. Rep.
6
,
30206
(
2016
).
28.
J.
Xu
,
S.
Xiao
,
C.
Wu
et al, “
Broadband one-way propagation and rainbow trapping of terahertz radiations
,”
Opt. Express
27
,
10659
10669
(
2019
).
29.
J.
Xu
,
Q.
Shen
,
K.
Yuan
et al, “
Trapping and releasing bidirectional rainbow at terahertz frequencies
,”
Opt. Commun.
473
,
125999
(
2020
).
30.
K. L.
Tsakmakidis
,
T. W.
Pickering
,
J. M.
Hamm
, et al, “
Completely stopped and dispersionless light in plasmonic waveguides
,”
Phys. Rev. Lett.
112
,
167401
(
2014
).
[PubMed]
31.
L.
Lu
,
J. D.
Joannopoulos
, and
M.
Soljačić
, “
Topological photonics
,”
Nat. Photonics
8
,
821
829
(
2014
).
32.
J.
Guglielmon
and
M. C.
Rechtsman
, “
Broadband topological slow light through higher momentum-space winding
,”
Phys. Rev. Lett.
122
,
153904
(
2019
).
33.
G.
Arregui
,
J.
Gomis-Bresco
,
C. M.
Sotomayor-Torres
et al, “
Quantifying the robustness of topological slow light
,”
Phys. Rev. Lett.
126
,
027403
(
2021
).
34.
B.
Davies
and
L.
Herren
, “
Robustness of subwavelength devices: A case study of cochlea-inspired rainbow sensors
,” arXiv:2109.15013.
35.
C.
Lu
,
C.
Wang
,
M.
Xiao
et al, “
Topological rainbow concentrator based on synthetic dimension
,”
Phys. Rev. Lett.
126
,
113902
(
2021
).
36.
H.
Yoshimi
,
T.
Yamaguchi
,
R.
Katsumi
et al, “
Experimental demonstration of topological slow light waveguides in valley photonic crystals
,”
Opt. Express
29
,
13441
(
2021
).
37.
L.
Yu
,
H.
Xue
, and
B.
Zhang
, “
Topological slow light via coupling chiral edge modes with flatbands
,”
Appl. Phys. Lett.
118
,
071102
(
2021
).
38.
Y.-H.
Chang
,
T.
Yamaguchi
,
R.
Katsumi
et al, “
Direct observation of topological protected edge states in slow-light
,” arXiv:2004.09282v1.
39.
B.
Yang
,
H.
Zhang
,
T.
Wu
,
R.
Dong
,
X.
Yan
, and
X.
Zhang
, “
Topological states in amorphous magnetic photonic lattices
,”
Phys. Rev. B
99
,
045307
(
2019
).
40.
A.
Arreola-Lucas
,
G.
Báez
,
F.
Cervera
et al, “
Experimental evidence of rainbow trapping and bloch oscillations of torsional waves in chirped metallic beams
,”
Sci. Rep.
9
,
1860
(
2019
).
41.
G. J.
Chaplain
,
D.
Pajer
,
J. M.
De Ponti
et al, “
Delineating rainbow reflection and trapping with applications for energy harvesting
,”
New J. Phys.
22
,
063024
(
2020
).
42.
G. J.
Chaplain
,
J. M.
De Ponti
,
G.
Aguzzi
et al, “
Topological rainbow trapping for elastic energy harvesting in graded Su-Schrieffer-Heeger systems
,”
Phys. Rev. Appl.
14
,
054035
(
2020
).
43.
J.
Chen
,
W.
Liang
, and
Z.-Y.
Li
, “
Switchable slow light rainbow trapping and releasing in strongly coupling topological photonic systems
,”
Photonics Res.
7
,
1075
(
2019
).
44.
H.
Zhang
,
L.
Qian
,
C.
Wang
et al, “
Topological rainbow based on graded topological photonic crystals
,”
Opt. Lett.
46
,
1237
(
2021
).
45.
V.
Ginis
,
P.
Tassin
,
T.
Koschny
et al, “
Broadband metasurfaces enabling arbitrarily large delay-bandwidth products
,”
Appl. Phys. Lett.
108
,
031601
(
2016
).
46.
O.
Tsilipakos
,
L.
Zhang
,
M.
Kafesaki
et al, “
Experimental implementation of achromatic multiresonant metasurface for broadband pulse delay
,”
ACS Photonics
8
,
1649
1655
(
2021
).
47.
I.
Cardea
,
D.
Grassani
,
S. J.
Fabbri
et al, “
Arbitrarily high time bandwidth performance in a nonreciprocal optical resonator with broken time invariance
,”
Sci. Rep.
10
,
15752
(
2020
).
48.
F. Y.
Gardes
,
K. L.
Tsakmakidis
,
D.
Thomson
et al, “
Micrometer size polarisation independent depletion-type photonic modulator in Silicon On Insulator
,”
Opt. Express
15
,
5879
5884
(
2007
).
49.
K. L.
Tsakmakidis
and
O.
Hess
, “
Extreme control of light in metamaterials: Complete and loss-free stopping of light
,”
Physica B
407
,
4066
4069
(
2012
).
50.
K. L.
Tsakmakidis
,
O.
Reshef
,
E.
Almpanis
et al, “
Ultrabroadband 3D invisibility with fast-light cloaks
,”
Nat. Commun.
10
,
4859
(
2019
).
51.
K. L.
Tsakmakidis
,
O.
Reshef
,
E.
Almpanis
et al, “
Reply to ‘Physical limitations on broadband invisibility based on fast-light media
,”
Nat. Commun.
12
,
2800
(
2021
).
52.
J. R.
Lowell
and
E.
Parra
, “
Applications of slow light: A DARPA perspective
,”
Proc. SPIE
5735
,
80
86
(
2005
).
53.
S.
Farid
,
K.
Dixon
,
M.
Shayegannia
et al, “
Rainbows at the end of subwavelength discontinuities: Plasmonic light trapping for sensing applications
,”
Adv. Opt. Mater.
(to be published).
54.
K. L.
Tsakmakidis
,
R. W.
Boyd
,
E.
Yablonovitch
, and
X.
Zhang
, “
Large spontaneous-emission enhancements in metallic nanostructures: Towards LEDs faster than lasers
,”
Opt. Express
24
,
17916
17927
(
2016
).
55.
K. L.
Tsakmakidis
, “
Stopped-light nanolasing in optical magic-angle graphene
,”
Nat. Nanotechnol.
16
,
1048
(
2021
).
56.
O.
Hess
and
K. L.
Tsakmakidis
, “
Metamaterials with quantum gain
,”
Science
339
,
654
(
2013
).
57.
O.
Hess
,
J. B.
Pendry
,
S. A.
Maier
,
R. F.
Oulton
,
J. M.
Hamm
, and
K. L.
Tsakmakidis
, “
Active nanoplasmonic metamaterials
,”
Nat. Mater.
11
,
573
(
2012
).
58.
J.
Zhu
,
Y.
Chen
,
X.
Zhu
et al, “
Acoustic rainbow trapping
,”
Sci. Rep.
3
,
1728
(
2013
).
59.
Y.
Saito
and
T.
Baba
, “
Stopping of light by the dynamic tuning of photonic crystal slow light device
,”
Opt. Express
18
,
17141
17153
(
2010
).
60.
Q.
Shen
,
J.
Yan
,
X.
Zheng
, and
L.
Shen
, “
Ultrawideband unidirectional surface magnetoplasmons based on remanence for the microwave region
,”
Opt. Mater. Express
11
,
2335
2347
(
2021
).
61.
N.
Jiménez
,
V.
Romero-García
,
V.
Pagneux
et al, “
Rainbow-trapping absorbers: Broadband, perfect and asymmetric sound absorption by subwavelength panels for transmission problems
,”
Sci. Rep.
7
,
13595
(
2017
).
62.
Y.
Cui
,
K. H.
Fung
,
J.
Xu
et al, “
Ultrabroadband light absorption by a sawtooth anisotropic metamaterial slab
,”
Nano Lett.
12
,
1443
(
2012
).
You do not currently have access to this content.