Polarization switching characteristics in a 1550 nm
VCSEL subject to circularly polarized optical injection
Haiying Qiu (邱海英)
1
, Zhengmao Wu (吴正茂)
1,
*, Tao Deng (邓 涛)
1
,
Yang He (何 洋)
1
, and Guangqiong Xia (夏光琼)
1,2
1
School of Physical Science and Technology, Southwest University, Chongqing 400715, China
2
e-mail: gqxia@swu.edu.cn
*Corresponding author: zmwu@swu.edu.cn
Received September 17, 2015; accepted November 19, 2015; posted online January 4, 2016
Polarization switching (PS) characteristics in a 1550 nm vertical-cavity surface-emitting laser (VCSEL) subject
to circularly polarized optical injection (CPOI) are experimentally investigated. The results show that, under
different biased current, a solitary 1550 nm VCSEL can oscillate at y polarization mode (y mode), two polari-
zation components (PCs) coexistence or x polarization mode (x mode). The PS characteristics induced by
CPOI for the VCSEL operating at y mode and x mode are analyzed and the evolutions of dynamical states
with the injected power are discussed. Additionally, the mappings of nonlinear dynamical states are given
in the parameters space of the injected power and frequency detuning.
OCIS codes: 140.7260, 190.3100, 190.4360.
doi: 10.3788/COL201614.021401.
The nonlinear dynamics including optical switching and
bistability occurring in edge-emitting semiconductor
lasers (EELs)
[1–6]
and vertical-cavity surface-emitting
lasers (VCSELs)
[7–25]
are interesting phenomena and have
attracted extensive attention for their potential applica-
tions in optical interconnects and all-optical signal proce ss-
ing. Polarization switching (PS) phenomenon and its
associated polarization bistabilit y (PB) in VCSELs has
become relevant research focuses because of these unique
advantages such as reduced manufacturing costs, low-
threshold current, larger modulation bandwidth, single-
longitudinal-mode operation, circular output beam, etc.
[26]
.
Previous works have demonstrated that the PS and PB can
be obtained through continuously varying the biased cur-
rent or device temperature of a VCSEL
[11,12]
, or introducing
an external disturbance such as current modulation
[13]
,
optical feedback
[14–16]
, or optical injection
[18–25]
.
Since PS in a short-wavelength VCSEL subject to
optical injection was experimentally demonstrated for
the first time to our knowledge by Pan et al.
[21]
, optical
injection has become a common method to obtain PS in
VCSELs
[22–25]
. Optical injection, which is introduced to
achieve PS, generally includes three types: orthogonal
optical injection, variable-polarization optical injection,
and circularly polarized optical injection (CPOI). PS char-
acteristics in VCSELs subject to orthogonal optical injec-
tion have been extensively investigated. For instance,
Gatare et al. experimentally studied the injection strength
induced PS in an 850 nm VCSEL subject to orthogonal
optical injection
[22]
. Torre et al. analyzed theoretically
and experimentally the injected power required for PS
as a function of the frequency detuning in long-wavelength
VCSELs subject to orthogonal optical injection
[23]
.
Quirce et al. observed different types of PS in a 1550 nm
VCSEL subject to orthogonal optical injection
[24]
. For PS
in a VCSEL subject to variable-polarization optical injec-
tion, Al-Seyab et al. theoretically investigated the input
polarization angle required for PS in a 1550 nm VCSEL
subject to optical injection of arbitrary polarization
[25]
.
Relative to the two optical injection schemes mentioned
above, PS characteristics in a VCSEL subject to CPOI
is rarely reported though the circular PS and PB in a
1300 nm spin-VCSEL subject to CPOI have been exper-
imentally observed
[27]
.
In this Letter, we report an experimental investigation
of the PS characteristics in a 1550 nm VCSEL subject to
CPOI. The evolution of different nonlinear dynamical
behaviors for the 1550 nm VCSEL subject to CPOI have
been presented, and the mappings of dynamical behaviors
in the parameter space of the injected power and the fre-
quency detuning have also been given.
Figure
1 shows the schematic of the experimental setup.
The output of a tunable semiconductor laser source (Ando
AQ4321A) first passes through an erbium-doped fiber
amplifier (EDFA1, Corning PureGain 2500C), a variable
attenuator (VA1), a polarization controller (PC), an
optical isolator (OI1), and then is split into two parts
by a 10/90 fiber coupler (FC1). One part is connected
to a power meter (PM) to monitor the injected power
P
inj
. The other is transformed into circular polarization
light via an aspheric lens (AL1), OI2, a polarizer (P),
and a quarter-wave plate (QWP) whose optical axis is
positioned at 45° relative to the transmission axis of the
polarizer. The polarization characteristics of the output
from the QWP can be determined through sending it to
another polarizer named as an analyzer. Rotating contin-
uously the analyzer and detecting the transmitted power
from the analyzer, the output from the QWP can be
judged as circular polarization light once the detecting
power keeps a constant. Then, such circular polarization
COL 14(2), 021401(2016) CHINESE OPTICS LETTERS February 10, 2016
1671-7694/2016/021401(5) 021401-1 © 2016 Chinese Optics Letters