All-optical modulator with long range surface plasmon resonance
Xueliang Shi, Shilie Zheng, Hao Chi, Xiaofeng Jin, Xianmin Zhang
n
Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China
article info
Article history:
Received 27 December 2012
Received in revised form
26 January 2013
Accepted 2 February 2013
Keywords:
All-optical modulator
Long rang surface plasmon resonance
Kerr effect
abstract
An all-optical modulator based on long range surface plasmon resonance with respect to Kerr effect
induced refractive index changes is proposed and numerically investigated. The photosensitivity of the
Kerr-polymer induces the variation of refractive index under illumination of pump light with different
intensity. Long range surface plasmon resonance excited by an attenuated total internal reflection
structure is utilized in the design for its high sensitivity to refractive index. For the structure with
optimal parameters, the modulator is able to vary the reflectance from 0.04 to 0.74 by applying a pump
light as low as 0.44 GW/cm
2
.
& 2013 Elsevier Ltd. All rights reserved.
1. Introduction
In the field of optical communication systems, all-optical
devices and data processing are playing a more and more
important role. Most of the applications are based on the non-
linear optical effects and a stable material with sizeable nonlinear
response can achieve a high operating efficiency at low optical
pump intensity. Kerr effect has been introduced in all-optical
devices such as modulator, switching and so on. Ermolenko and
coworkers proposed and experimentally confirmed a concept of
ultrafast all-optical modulator at wavelength of 1.5
m
m [1].
Zhang and coworker theoretically and experimentally investi-
gated an all-optical switching based on the cascaded long-
period fiber gratings by utilizing the Kerr optical effect in the
erbium-doped fiber [2]. Many other all-optical devices realized
by inorganic material are limited by weak nonlinearity, slow
response time and difficulty of discrimination between thermal
and Kerr nonlinearity at room temperature [3]. Recently, various
types of work have been explored extensively on dye doped organic
polymers, which offer significant advantages than inorganic
material [4]. Those organic polymers have a sizeable Kerr non-
linearity and are able to obtain a large refractive index change
with a low pump light. All-optical modulation and switching with
a response time ranging from microsecond to sub-picosecond
have been demonstrated using those polymers [5].
A nonlinear optical response with increased efficiency can be
achieved by nonlinear plasmonics and many works have been
done [6]. Wurtz and coworkers proposed plasmonic nanorod
metamaterials with an enhanced, ultrafast, nonlinear optical
response, which can lead to ultrafast, low-power all-optical
information processing in subwavelength-scale devices [7].
Krasavin and coworkers demonstrated an all-plasmonics modula-
tion by using stimulated emission of copropagating surface
plasmon polaritons (SPRs) on a substrate with gain [8]. Surface
plasmon resonances are electromagnetic excitations propagating
at the interface between a metal and a dielectric and have
attracted much more attentions in many applications [9]. SPR
can be excited by p-polarized light with the assistance of a total
internal reflection (ATR) structure [10] or a grating structure [11].
The excitation condition is highly sensitive to the refractive index
of the material near the metal surface, which makes SPR can
be used to sense the refractive index change induced by the
nonlinear effect. Okamoto and coworkers first demonstrated an
all-optical spatial light modulator with surface plasmon reso-
nances using the thermo-optic effect of the polymer film [12].
Nagamuraa and Hamada proposed an improved modulator with
less response time and lower pump intensity [13]. Compared
to thermo-optic effect, Kerr effect can provide a response time
of sub-picosecond but less third-order nonlinearly. All-optical
devices based on Kerr effect with fast response time and low
pump light can be realized by utilizing the high sensitivity of SPR.
Margheri and coworkers proposed an all-optical switch based
on SPR, achieved a variation of Kerr induced refractive index of
the nonlinear medium
W
n¼0.0041 with the pump intensity of
4.8 GW/cm
2
[14]. Chen and coworkers numerically demonstrated
a sensitivity enhanced all-optical switch using Kerr effect with a
pump threshold as low as 0.9 GW/cm
2
[15].
In this paper, we propose an all-optical modulator based on
the third-order Kerr nonlinearity. The modulator is based on ATR
structure to excite long range surface plasmon resonances, which
Contents lists available at SciVerse ScienceDirect
journal homepage: www.elsevier.com/locate/optlastec
Optics & Laser Technology
0030-3992/$ - see front matter & 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.optlastec.2013.02.001
n
Corresponding author. Tel.: þ86 571 8795 2373; fax: þ86 571 87951 759.
E-mail addresses: zhangxm@zju.edu.cn, zhangxm@ieee.org (X. Zhang).
Optics & Laser Technology 49 (2013) 316–319