제목: Ultrafast broadband nonlinear
photonics based on graphene
일시: 2021년 5월 11일(화) 오후 5시
Speaker: 이상민(F. Rotermund)
Abstract:
Graphene
and graphene-based materials have been widely investigated for diverse
applications in electronics, electro-optics and photonics. In particular, since
graphene exhibits very large optical nonlinearity with ultrafast response in a
broad spectral range, graphene can be applied for broadband high-speed
nonlinear modulators and switches. Saturable absorbers (SAs) are passive
switching devices based on intensity-dependent optical nonlinearity.
Q-switching and mode-locking by employing appropriate SAs are widely used techniques for pulsed operation of diverse lasers. Compared to conventional SA including widespread
semiconductor
saturable absorber mirrors (SESAMs) [1], graphene-based
SAs exhibit superior advantages of ultrafast saturable absorption over
ultrabroad spectral region, even far beyond 2000 nm without additional bandgap engineering [2-4].
In addition to graphene as broadband SAs for laser mode-locking
and Q-switching, interesting nonlinear optical phenomena and characteristics
are investigated in the THz frequency range. For example, THz
nonlinearities of graphene can be remarkably accelerated by stacking disorder
of monolayer graphene or in combination with meta- and nanogap-structures [5-8].
In this talk,
universal use of graphene SAs for
mode-locking and Q-switching of various compact lasers are reviewed. In
addition, interesting features of graphene and graphene-based materials in the
THz region will be also presented.
[1]
U.
Keller et al.,
IEEE J. Sel. Top. Quant. Electron.
2, 435 (1996).
[2]
W.
B. Cho et al., Opt. Lett. 36, 4089 (2011).
[3]
E. J. Lee, et al.,
Nat. Commun. 6, 6851(2015)
[4]
W. B. Cho et al., Opt. Express 24,
20774 (2016)
[5]
Y.-M. Bahk, et al., Phys. Rev. Lett. 115, 125501 (2015).
[6]
K. Miyamoto et al., Sci. Rep. 6, 38880 (2016).
[7]
H. J.
Choi, et al., Sci.
Rep. 7, 42833 (2017).
[8] I. H. Baek, et al., 2D Mater. 4, 025035 (2017).