Show all abstracts
View Session
- Front Matter
- Optical Manipulation and Frequency Conversion
- Nonlinear Fiber Optics and Nonlinear Materials
- Quantum Optics Phenomena in Laser and Atom-System Interactions
- Quantum Communication Related Nonlinear optical Phenomena
- Poster Session
Front Matter
Front Matter: Volume 7846
Show abstract
This PDF file contains the front matter associated with SPIE Proceedings volume 7846, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
Optical Manipulation and Frequency Conversion
Rabi splitting in a subwavelength cavity constructed by metamaterials
Show abstract
In this paper, we experimentally study the Rabi splitting in a subwavelength cavity constructed by single-negative (SNG)
metamaterials. First, the SNG metamaterials are fabricated by using coplanar waveguide with lumped-element series
capacitors and shunt inductors loading. Then, the subwavelength cavity is constructed based on the SNG metamaterials.
Finally, Rabi splitting in the subwavelength cavity is experimentally realized.
Generation of 1178nm based on cascaded stimulated Raman scattering in KTA crystal
Show abstract
We report the generation of 1178nm based on cascaded Raman scattering in KTA crystal intracavity pumped by a AO
Q-switched Nd:YAG laser. The output power at 1178nm is around 80mW when the diode pump power was 7.6W at
808nm. At the same time, the low-order Stokes waves at 1091nm, 1120nm, 1146nm and visible yellow laser at 573nm
(the second harmonic wave of 1146nm) are also detected. The total Stokes output power was 240mW and the yellow
laser was 115mW. The power at 1178nm can be increased with output mirrors that are more suitable. The spectra of the
generated wavelengths were experimentally analyzed and they accords well with theoretical results.
Nonlinear Fiber Optics and Nonlinear Materials
Periodically erasing the second-order optical nonlinearity in thermally poled optical fibers with UV light
Show abstract
In the paper, we report experimental results of the effect of UV-light exposure on the profile of thermal poling induced
second-order optical nonlinearity (SON) in twin-hole optical fibers. Before UV-exposure, uniform thermal poling at
320°C and 3.5 kV along a 5-7 cm long section of twin-hole fiber produced a uniform SON of 0.263 pm/V in the fiber
core. A focused light beam from a frequency-doubled Ar+ laser operating at 244 nm was used to locally erase the
induced nonlinearity in the fibers to create a periodic structure for quasi-phase matching applications. The UV-exposed
fibers were then observed under a second-harmonic microscope to characterize the distribution profile of any residual
nonlinearity after exposure. Effects of scanning speeds of the laser beam on the length of nonlinearity-erased section and
amplitude of the residual nonlinearity were investigated. It was found that the required UV-light fluence to fully erase
the induced nonlinearity is only ~0.5% of that typically required for fabricating fiber Bragg gratings.
Observation of the fast and slow light in an optical fiber based on SBS gain region
Shoujun Zhang,
Xiaoyan Li,
Xianpu Su,
et al.
Show abstract
Fast and slow light in optical fibers was a powerful tool for future all-optical networks. We observed fast and slow light
based on the stimulated Brillouin scattering using the gain region in optical fibers just adjusting the pump power
experimentally. In this paper, the time delay as a function of the pump signal power, Stokes signal power and the fiber
length were studied.
A novel of low-dispersion high-birefringence crystal fiber with high-nonlinear for four-wave mixing
Ya-Ni Zhang
Show abstract
We propose a novel of photonic crystal fiber (PCF) with low dispersion high birefringence for four wave mixing. This
fiber is composed of a solid silica core and a cladding with squeezed-hexagonal-lattice circular air-holes along the fiber
length. Dispersion and birefringence are investigated simultaneously by using the full vectorial finite element method.
Numerical results show the proposed fiber possesses the property of low-dispersion and high-birefringence, with the
result of the total dispersion being within ±5 ps•nm-1km-1 over ultra broad wavelength range from 1360 to 1670 nm and
the corresponding high birefringence being about 1.5×10-2 at 1550 nm. Furthermore, the nonlinear coefficient of the
proposed fiber is also numerically analyzed, and present high nonlinear effects. Therefore, high birefringence, low
flattened dispersion and high nonlinear effects are combined in the proposed PCF perfectly, which has the great
significance for the four-wave mixing.
Donor strengthening strategy for FTC-based organic nonlinear chromophore
Show abstract
The molecular chromphores with high first hyperpolarizability values have been reported with the development of
conjugated polyene-bridge or thiophene-bridge system and strong tricyano-containing heterocyclic electron acceptors. In
this work, we investigated the enhancement of the electro-optic response by introducing various groups, such as OCH3,
Ophenel, OTBDMS, etc, as an additional donor part on conventional FTC type donor-π-acceptor molecules. These new
type donors exhibited a strong solvatochromic effect, indicating an extra donation to the pi-conjugated bridge, which
shifted the charge-transfer absorption of the chromophores to the lower energy region. Furthermore, the simple
modification on the donor moiety resulted in a great improvement in the first hyperpolarizability and macroscopic
electro-optic coefficient (r33) over the benchmark dialkylamino FTC counterparts. For the real applications, the stronger
acceptor was adopted to further increase the r33 and such a chromophore was post-functionalized as side-chain polymer
to enhance the temporal stability.
Microwave signal generation with the frequency-selective sideband injection-locking of semiconductor lasers
Show abstract
Two longitudinally multimode Febry-Perot diode lasers have been sideband injection-locked to the +1 and -1
sidebands of a 3.4GHz electro-optical modulator (EOM). Optical heterodyne measurement showed that powers of 99.5%
of the slave laser could be injection-locked to the +1 or -1 sidebands, and the unselected master laser carrier was
suppressed down to -24dB. Generally, the long-term stability and efficiency of the injection-locking to the +1 sideband
was worse than the -1 due to the asymmetry of the injection-locking bandwidth. The microwave signal at 6.8GHz had a
measured 3dB linewidth of less than 200Hz, without considering the noise contribution by the driving signal of the
additional acousto-optical modulator. The proposed method will be used for driving the stimulated Raman transitions in a
Rubidium based atom gyroscope.
Quantum Optics Phenomena in Laser and Atom-System Interactions
Performance comparison of nonlinear crystals for frequency doubling of an 894nm Cs vapor laser
Show abstract
An examination of the efficiencies of three commonly used nonlinear crystals (PPKTP, LBO, and BiBO) when
generating second harmonic of a Cesium laser is presented. The experiment investigates both the intracavity and single
pass second harmonic generation of 895 nm Cs laser light when operating in quasi-CW and in CW modes and pumped
by several watts. A degradation of the conversion efficiencies for each crystal was observed when high fundamental
powers or a high duty cycle of the pump were used. For a Cs laser operating at 894nm, PPKTP is found to be the optimal
crystal for intracavity SHG in both pulsed and CW modes when operating at SHG powers of several watts. At higher
powers, however, the increased absorption coefficient of PPKTP at 447nm, compared to that of BiBO or LBO, may
become significant to where another crystal will be more appropriate for this application. Maximum blue light power
obtained with PPKTP crystal was about 1.5W in CW mode and 2.5W in QCW.
Phase modulation of electromagnetically induced grating in a four-level system
Zhi-Hong Xiao,
SungGuk Shin,
Kisik Kim
Show abstract
Electromagnetically induced phase grating (EIPG) is investigated in a microwave-coupled four-level
atomic system, where the two closely spaced lower levels are driven by a microwave field. In the
presence of a microwave field, the diffraction efficiency of grating is improved greatly by phase
modulation. For this case, one can properly tune the interaction length of the atomic sample, modulate
detuning of the microwave and the probe fields, and obtain the high diffraction efficiency of 32%
approximately.
Characterizing double-resonance optical-pumping spectra of cesium 6P3/2 - 8S1/2 excited-state transition and its application
Show abstract
The spectra of cesium 6P3/2 - 8S1/2 excited-state transition have been obtained using double resonance optical-pumping
(DROP) technique in a room-temperature vapor cell, and have shown a much better signal-to-noise ratio (SNR)
compared with that using the traditional optical-optical double resonance (OODR) method. Furthermore, the line-width
of DROP spectra is obviously narrowed by electromagnetically-induced transparency (EIT) effect in cesium 6S1/2 F=4 -
6P3/2 F'=5 - 8S1/2 F''=4 transitions. Finally, such DROP spectrum of 6P3/2 F'=5 - 8S1/2 F''=4 transition with a high SNR
and a narrow line-width is applied into frequency stabilization of a 795 nm external-cavity diode laser, and the residual
frequency fluctuation is ~ 600 kHz within 500 s.
Ghost imaging with XY phase series space light modulator
Jiexin Qin,
Shichao Liu,
Genghua Huang,
et al.
Show abstract
Ghost imaging has emerged a decade ago as a new imaging technique. Its feature is the image will appear on the optical
path, which never passes through the object actually. In this paper, we will give an overview of quantum imaging,
include the experiments with two-photon entanglement state source generated by spontaneous parametric down
conversion, as well as with pseudo-thermal light. Then we will show our ghost imaging experiment scheme with the
pseudo-thermal light source. We obtain the pseudo-thermal source by using a XY Phase Series Spatial Light Modulator
(supplied by BNS company) to modulate the laser light. This spatial light modulator changes the phase of the output light
field by controlling the loading element on every pixel.
Quantum Communication Related Nonlinear optical Phenomena
Comparison of dispersion compensation in a 40Gbps WDM optical communication system
Kaikai Xu
Show abstract
Dispersion management in single mode fiber (SMF) can be accomplished in many ways, though the most widely used
approach employs lengths of transport fiber of opposite dispersion characteristics to the principal fiber in the link,
usually standard single mode fiber (SSMF). Typically, a 10 to 20km length of dispersion compensating fiber (DCF) is
placed before the regenerators inducing negative dispersion to compensate for the positive dispersion accumulated over
the 60 to 80km length of the SMF. Analysis and comparison of the pre-compensation scheme and the post-compensation
scheme have been done. Due to the interplay between dispersion, nonlinearity, and signal power, the dispersion affects
the pulse evolution.
Unconditional security of relativistic quantum key distribution protocol
Show abstract
Relativistic quantum key distribution (QKD) protocol is a kind of modified BB84 QKD protocol based
on the principles of not only quantum mechanics but also special relativity. Its advantage compared with
BB84 protocol is that all of the qubits could be used for key generation, and Alice and Bob are able to select
any measuring bases. We prove its unconditional security against coherent attack via the method based on
CSS codes: begin with a modified EPR based protocol which can be proved unconditionally secure, then
reduce the protocol to a CSS codes based protocol. Finally, the CSS codes based protocol is demonstrated
equivalent to the relativistic QKD protocol, and we arrived at the conclusion of the unconditional security of
the final key.
Analysis of the coefficient of QBER and its influence on QKD
Show abstract
The quantum bit error rate (QBER) based on the weak coherent pulse's quantum key distribution is analyzed. It is
indicate that the coefficient of QBER is not a constant but is increased exponentially with the transmission distance.
Based on the three groups' experimental data, the function fitting for the coefficient of QBER has been done respectively.
We discovered that these fitting functions have the same function form. Subsequently we use fitting function to optimize
the mean photon number for the BB84 quantum key distribution with decoy states. The result shown that the optimized
mean photon number depend on the transmission distance. Using these results and the GYS's experimental parameters
we compared the key generation rates proposed by Lo et al with the modified one. We find that the latter is superior to
the former within a certain distance.
Principles and improvements of quadrature-based QKD
Show abstract
An overview of quadrature-based quantum key distribution is provided. Beginning from the comparison between
single-photon schema and continuous variable schema, the article focuses on the classical and state-of-art
protocols. Protocols' main procedures and security analysis are introduced, which includes the methods under
individual attack and collective attack. Then recent development of unconditional security proof is introduced
including the optimality of Gaussian attack and de Finetti theorem. Introduction towards discrete modulated
schemas' security proof is also made. At last, the article discusses experimental realization of various protocols
and the main trend in this field.
Poster Session
Efficient preparation of multipartite entanglement of atomic ensembles
Show abstract
We propose an efficient scheme to prepare multipartite entanglement of atomic ensembles trapped in separate cavities.
Our scheme has high fidelity even with realistic noise based on the repeat-until-success strategy. By employing the
quantum memory of the atomic internal state, the scaling efficiency decreases only with the number of atomic ensembles
by a slow polynomial law. Moreover, the atomic ensembles also can function as quantum repeaters, which enable our
system to compatible with the current experimental technique for quantum communication using atomic ensembles.
Achieving efficient and stable coherent population transfer by ultrashort double pulses
Zhendong Wang,
Kening Jia,
Ying Liang,
et al.
Show abstract
It is shown that, when two femtosecond chirped Gaussian pulses with equal pulse area and same size but opposite sign of
the chirp coefficient, which will be simply called as double pulses, overlap and propagate in the three-level Λ-type
atomic medium, both coherence between the double pulses and interaction between the double pulses and the atomic
medium arise. Adjusting size of the chirp coefficient can change shape, i.e. field distribution, of the composite pulse of
the double pulses, at the same time affect the interaction between the composite pulse field and atoms, and thereby
control oscillation process and value of the atomic population. By selecting suitable size of the chirp coefficient, we can
make the atoms at the lowest level exciting completely to the higher level; moreover the new population distribution is
stationary. It is also show that, for the double pulses with any area, efficient and stable population transfer always can be
realized by adjusting size of the chirp coefficient. And this conclusion doesn't vary with the pulse width or the medium
density varying.
An analytic expression of spontaneous emission FWHM in GaAs planar micro-cavity
Show abstract
The full-width half maximum (FWHM) is one of important parameters that can exhibit the micro-cavity effect. An
approximate analytic expression of spontaneous emission for GaAs micro-cavity in our previous work can be instead of
the numerical integral, but it is so complex that it cannot give the analytic expression of FWHM. This paper will set up
another approximation to give a new analytic expression of spontaneous emission, which can give the same results with
the numerical integral in the vertical direction, in which Fermi-Dirac distribution functions of electrons in the conduction
band and the valence band are considered. Although the new approximate analytic expression is simpler than that in our
previous work, it can be used to study the spontaneous emission spectra FWHM with a small angle in the vertical
direction of planar micro-cavity. The two approximate expressions of FWHM for enhancement spontaneous emission
spectrum into the small angle are obtained by the new analytic expression of spontaneous emission, in which the
triangular function relation and the first order series of sine and cosine are used respectively. The curves for the FHWM
versus the reflectivity by the two expressions of FWHM in the GaAs micro-cavity are also compared.
Investigation of parabolic pulse generation in a normal dispersion-decreasing-linearly fiber
Ge Xia,
Li Liu,
Songzhan Li,
et al.
Show abstract
It is known that parabolic pulses can be generated by use of a normal dispersion-decreasing fiber in a "passive" manner.
However, it is more practicable and significant for the dispersion-decreasing-linearly profile to be considered than for
any other profiles once actual fiber manufacture were taken into account. In this work, we investigate the process of
parabolic pulse generation (PPG) in a normal dispersion-decreasing-linearly fiber (NDDLF). Based on the principle of
virtual "equivalent" gain, we transform the nonlinear Schrodinger equation (NLSE) with linearly decreasing dispersion
into one of the form with "hyperbolic" gain and uniform dispersion. By numerically solving the two forms of NLSE, we
demonstrate that wave breaking (WB) can still take place during the evolution and the WB point is the threshold that
FWM begins to take effect. The distance where WB happens can be determined by the chirp oscillations appeared in the
pulse edges. Furthermore, by introducing two dimensionless structural functionals to characterize the pulse temporal and
spectral shape respectively, we also illustrate that these results are in consistent with that obtained from a
dispersion-decreasing-hyperbolically fiber (NDDHF) except that WB occurs much ahead and both functional values are
less close to the standard "parabolic shape" value 0.0720 for comparison.
Phase-dependent gain without inversion in an inhomogeneous broadened quasi ∧-type four-level system with VIC
Zhongbo Liu,
Zhendong Wang,
Kening Jia,
et al.
Show abstract
The effect of the relative phase (φ) between the probe and driving fields on the gain without inversion (GWI) is studied in a Doppler broadened quasi Λ-type four-level atomic system with vacuum induced coherence (VIC). It is shown that: The probe detuning region in which GWI exists and size of GWI are very sensitive to variation of the relative phase, the Doppler width ( D ) also has dramatically modulation role on the phase-dependent GWI. The GWI maximum value ( Gmax ) varies periodically with the relative phase varying, the period is 2π; but the concrete varying rule is closely related to the value of the Doppler width. In the case of D = 0 (i.e. without Doppler broadening) , when 0 < φ < π, Gmax increases monotonously with φ increasing; when π <φ < 2π, Gmax decreases monotonously with φ increasing; when φ =π, Gmaxhas the largest value. Under the condition of D ≠ 0 (i.e. Doppler broadening presents), in both regions 0 < φ < π and π < φ < 2π, Gmax does not monotonically increase or decrease with φ increasing; the value of φ, which corresponds to the largest value of Gmax, decreases gradually from π with D increasing, when value of D is large enough, the value of φ, which corresponds to the largest value of Gmax, is about π/2. In general speaking, Gmax decreases with D increasing; but Gmax larger than that in the corresponding static atomic system ( D = 0 ) can be gotten by choosing suitable values of φ and D.
Spectral properties of femtosecond chirped Gaussian pulse propagating in a dense three-level Λ-type atomic medium
Zhendong Wang,
Zhongbo Liu,
Ying Liang,
et al.
Show abstract
It is shown that, variation of the sign and size of the chirp coefficient (C) of the pulse has considerable effect on spectral
properties of the pulse and the effect is closely relative to size of the pulse area. When the pulse with smaller area, 2π
pulse, propagates in the medium, pulse splitting doesn't occur and the pulse evolves gradually to an approximate normal
Gaussian pulse (C=0); new high frequency component doesn't basically appear; with increasing value of C, oscillation
amplitude of blue shift and red shift components increases and blue shift component oscillates more severely; moreover,
the strength of the spectral component near the central frequency decreases considerably but the strength of blue shift
component increases obviously. When the 4π pulse propagates in the medium, the pulse will split into sub-pulses with
different numbers and shapes, new high frequency component can be produced, but the strength of the high frequency
component is smaller; similar to the case of 2π pulse, blue shift component oscillates more severely; in addition, the
strength of the spectral component with higher frequency decreases evidently with increasing value of C. When the pulse
with larger area, 8π pulse, propagates in the medium, the pulse splitting is similar to that in the 4π pulse case, but supercontinuum
spectrum with larger strength, higher frequency and wider frequency range than that in the 4π pulse case can
be obtained; varying the sign and size of C can not produce new high frequency component, but can change strength of
different frequency components in the spectrum, thus can get high frequency components with higher strength
Generation of tunable coherent nanosecond 8-12μm mid-infrared pulses based on difference frequency generation in GaSe and ZnGeP2
Show abstract
Based on the theoretical analysis on the phase-matching relations, effective nonlinear coefficients, walk-off and
acceptance angles, the generation of tunable and coherent nanosecond mid-infrared radiation covering the 8-12μm range
is realized by use of difference frequency generation (DFG) in a GaSe and a ZnGeP2 (ZGP) crystal. Using an 8-mm-long
GaSe crystal, we achieve the mid-infrared generation that is continuously tunable from 8.28μm to 18.365μm. The
maximum pulse energy is 31μJ at 8.76μm, corresponding to the conversion efficiency of 0.9% and the maximum midinfrared
peak power of about 7kW. In the case of using an 8-mm-long ZGP crystal, the tuning range is from 7.2μm to
12.2μm. The maximum pulse energy is about 10μJ at 9.22μm, corresponding to the conversion efficiency of 0.45% and
the peak power of 2.2kW.
Dispersion and nonlinearity in subwavelength-diameter optical fiber with high-index-contrast dielectric thin films
Show abstract
We have investigated the dispersion and the nonlinearity properties of the subwavelength-diameter optical fiber (SDOF)
with high-index-contrast dielectric thin films. The dispersion length and the nonlinearity length have been calculated to
discuss the propagation properties of pulse in SDOF. The waveguide dispersion and nonlinearity analysis is used to
guide the waveguide dimension design for possible applications. The high nonlinearity of SDOF makes it especially
suitable for nonlinearity devices.
Incoherent dark solitons splitting in LiNbO3:Fe crystal
Show abstract
We observed experimentally one-dimensional even-number sequence of dark photovoltaic solitons in LiNbO3:Fe crystal
without additional background illumination with spatially incoherent beam that contains a dark stripe generated from an
amplitude jump in the center of the incoherent beam. In experiment, we found that the initial stripe width at the
entrance face of the crystal is a key parameter for generating an even-number sequence of dark incoherent photovoltaic
solitons. If the initial width of the dark stripe was small, only a Y-junction soliton pair was generated. As the initial
width of the dark stripe was creased to 20.1μm, the stripe can split into an even-number sequence of soliton structure.
The soliton pairs far away from the center had smaller width and less visibility. In addition, the separations between
adjacent dark stripes became slightly smaller than that of the Y-junction dark solitons. In particular, when the input
width in the entrance face of the crystal was 30.8μm, the diffractive beam in the output face of the crystal was no longer
expanding its outer boundary, but shrank its width.
Pulse compression of negatively chirped pulses in silicon photonic nanowire
Show abstract
Pulse compression of initial negative frequency chirp pulses in silicon photonic nanowire has been analyzed numerically.
The effects of the initial negative frequency chirp and core diameter variation on pulse compression have been
numerically investigated. By analyzing the interaction of SPM, positive group-velocity dispersion and the initial negative
frequency chirp, we find that the compression factor increases but the quality factor and the optimum fiber length
decrease with the increasing initial negative chirp when the core diameter is specified. A compression factor of 8.02 can
be achieved by a pulse with initial negative frequency chirp of -20 and initial FWHM duration of 30 fs in a 4.35 μm long
silicon nanowire.
Phase control of linewidth of electromagnetically induced transparency coupled by double fields
Show abstract
The effect of the relative phase on the spectral linewidth of electromagnetically induced transparency is studied in a
Λ-type three-level configuration coupled by double coupling fields and the result is presented in this paper. We show that
the relative phase between the double coupling fields has a great degree of influence on the spectral width of
electromagnetically induced transparency window. The linewidth can be controlled by changing the relative phase.
Particularly, as the double coupling fields have opposite phases, the linewidth of EIT window can be extremely narrow
distinctly.
Observation of bistable upconversion emission in Tm,Yb codoped yttria nanocrystal
Show abstract
Nonlinear upconversion emission properties in Tm and Yb codoped yttria nanocrystal have been studied under 973 nm
laser excitation. Intrinsic bistability and hysteresis have been observed for the bright blue upconversion luminescence of
Tm3+ ions at room temperature. The mechanism of the Tm3+ bistable emission is mainly related to laser-induced local
thermal effects which cause the enhancement of sequential multi-photon energy transfer upconversion of Yb3+-Tm3+
pairs.
Phase control of electromagnetically induced transparency in a four-level system
Show abstract
We present a theoretical study on the frequency position and the linetype of Electromagnetically Induced Transparency
(EIT) in a four-level atomic system with a coupling field, two microwave fields and a probe field. The absorption
spectrum which is characterized by two EIT windows is obtained by a weak probe field scanning corresponding
transition. It can be found that the frequency position and the linetype of EIT change with the relative phase of the two
microwave fields. The frequnecy interval reaches the minimum when the relative phase is reverse. If two microwave
fields have the same strength and reverse phase, the absorption spectrum will exhibit an EIT. This proposes a way to
controlling frequency position of EIT by modulating the relative phase between two fields.
Synthesis and 3PA induced optical limiting effect of a carbazole derivative
Show abstract
N-Butyl-3,6-diformylcarbazole (abbreviated as b) was synthesized by the reaction of N-alkylation and the product yield
was 45%. The structure was characterized by Nuclear Magnetic Resonance. Its optical properties were studied. The
compound had strong fluorescence emission, and the fluorescence quantum yield was 0.40. Utilized experiment,we
surveyed the effect of temperature on steady state fluorescence intensity, at 278K, 288K, 298K, 308K and 313K in DMF
respectively. The measurement of the three-photon absorption (3PA) induced optical limiting effect was done in a
10-mm-long transparent quartz cell, using a Q-switched Nd: YAG laser with pulse duration of 38 ps, repetition rate of 10
Hz at 1064nm. In the case of low incident intensity, the transmittance varied linearly with incident intensity. However,
the transmittance increased slowly under the condition of high incident intensity. The calculated results based on 3PA
theory agreed well with the experimental results and it was inferred that the optical limiting of the compound resulted
from its 3PA. The 3PA coefficient value was 6.1×10-23 cm6/w2 and its corresponding absorption section was
8.7×10-79 cm6s2.
The entanglement properties of photon subtracted two-mode Gaussian states
Show abstract
We analyze the entanglement condition of a new kind of non-Gaussian quantum
state, which is prepared by photon number subtraction from a two mode
Gaussian state. Fock space criterion and Shchukin-Vogel criterion are
applied and the results are compared. Two kinds of the original Gaussian
states are utilized. Their photon subtracted states have different
entanglement properties.
The cumulants of bosonic quantum states
Li-zhen Jiang
Show abstract
We address the issue of quantifying the non-Gaussian character of a bosonic
quantum state and introduce cumulants of quantum states as the measure of
non-Gaussianity. The cumulants are calculated for Fock state, cat state,
non-Gaussian state prepared by photon subtraction and phase damped state.
The time evolution of non-Gaussianity is also studied. The third-order
cumulant is a vector of length 4 and the fourth-order cumulant is a vector
of length 5 for single mode quantum state.
Evaluating the quantum capacity of bosonic dephasing channel
Show abstract
Phase damping is the main decoherence in the evolution of quantum states. In
most of the known quantum computing and quantum information processing,
devices have amplitude damping times that are around 1-2 orders of magnitude
larger than the corresponding dephasing times. For lossy optical fibre as a
quantum channel, the quantum capacity is well known. The channel is
degradable. We know that dephasing channel is also degradable, thus it can
be anticipate that the channel capacity is available. We calculate the
capacity with various methods in this paper.
Studying the VCSEL to VCSEL injection locking for enhanced chromatic dispersion compensation
Linfu Li
Show abstract
In order to supply a theoretical guide for digital chaotic telecommunication, the technique of Optical injection
locking (OIL) of semiconductor lasers on the chaotic communication have been investigated based on the theoretical
models used to describe the dynamics of solitary VCSEL subjected to the external optical injection and signal
transmission in fiber. The numerical simulation results show that, the frequency chirp and time-resolved chirp are
reduced in magnitude, using a VCSEL laser as master and another VCSEL as slave, it leads to a no-penalty transmission
over 50 km of uncompensated in SSMF at 10Gb/s, and it could be higher rate and more remote if there were appropriate
compensation.
Backward propagation of light pulse in phthalocyanin gallium PMMA at room temperature
Hao Wang,
Chunguang Zhang
Show abstract
Light speed control had been an interesting issue in recent years. In this work, the authors experimentally observed the
backward propagation of light pulse in Phthalocyanin Gallium polymethyl methacrylate (PMMA) at room temperature,
firstly. Taking use of the modulation technique, we got the time advancement of 260 μs when the sample length was 2
mm long and the modulation frequency was 50 Hz, the corresponding group velocity was -7.69m/s. The phenomenon of
backward propagation was a direct result of negative group velocity. And the energy flow still traveled in the forward
direction in the sample although the light propagated with a negative group velocity.
The switch between electromagnetically induced transparency and absorption due to the power broadening of probing field
Show abstract
In this paper we present a theoretical study of the nonlinear effect in the quasi-lambda type
four-level system. The system consists of an excited state level and three ground state hyperfine
levels. Probing and coupling field are coupled to between the excited state and two higher ground
states, and the microwave field drives the two lower ground states which are associated with
probing field. By solving the precision solutions of the equations of motion of density matrix, the
absorption properties as a function of Rabi frequencies of the probing field and microwave field
are given. As a result, the switch from double EIT to single EIA is found due to the power
broadening of probing field. However, the splitting frequency of double EIT has some connection
with the Rabi frequency of microwave field.
Double-resonance optical-pumping spectra of rubidium 5S1/2 - 5P3/2 - 4D3/2 transitions and frequency stabilization of 1.5-micrometer laser
Show abstract
We demonstrate the spectra of 87Rb 5S1/2 - 5P3/2 - 4D3/2 transitions by utilizing the double-resonance optical-pumping
(DROP) and optical-optical double-resonance (OODR) techniques, respectively. The DROP spectrum, compared with
the traditional OODR spectrum, show a much better signal-to-noise ratio (SNR). Paying special attention to the influence
of alignment of lasers where the coupling and probe beams are counter-propagation and co-propagation on DROP
spectrum, so as to further narrow the spectral width by means of electromagnetically induced transparency (EIT). When
-the frequency of 1.5μm fiber-pigtailed butterfly-type distributed-feedback (DFB) diode laser is stabilized to the DROP
spectrum of 87Rb 5P3/2 - 4D3/2 transition, the preliminary result of residual frequency jitter after stabilization is ~ ±1.3
MHz within 60 s.
Frequency doubling of 1560nm diode laser via PPLN and PPKTP crystals and frequency stabilization to rubidium absorption line
Show abstract
In our experiment, a polarization-maintaining (PM) fiber-pigtailed butterfly-sealed 1560nm distributed-feedback (DFB)
laser diode is amplified by a 5-Watt EDFA, then a multiple-period PPLN crystal (1mm×10mm×20mm) and a
single-period PPKTP crystal (1mm×2mm×30mm) are utilized to perform SHG via single pass configuration. The second
harmonic power of ~ 239 mW@780 nm for PPLN and ~ 210 mW@780 nm for PPKTP are obtained with ~5W@1560
nm laser input, corresponding to SHG efficiency of ~ 5.2% for PPLN and ~ 4.4% for PPKTP, respectively. Finally the
1560 nm laser diode's frequency is locked to rubidium absorption line via SHG and rubidium absorption spectroscopy,
the laser frequency drift for free-running case is ~ 56 MHz in 30 s, the residual frequency after being locked drift is ~ ±
3.5 MHz.
Theoretical study of optically-controlled group velocity of light in an optical fiber
Xianpu Su,
Xiaoyan Li,
Shoujun Zhang,
et al.
Show abstract
Three-wave coupled equations of optically-controlled group velocity of light based on stimulated Brillouin scattering
(SBS), together with their boundary and initial conditions, are solved using finite difference method. Relations of system
time delay, pulse broadening factor and changes of pulse shape with gain parameter are obtained, further more,
circumstance with different stokes power, pulse width, fiber length are discussed.
All-optical control of polarization and intensity of light in periodically poled lithium niobate
Show abstract
We propose a method to control the polarization and magnitude of light by introducing
another pump wave (control-light) in periodically poled lithium niobate (PPLN). Cascaded
polarization coupling and second harmonic generation (SHG) in a single PPLN are described by
the wave-coupling equations. The numerical simulations show that the control-light wave breaks
the original energy coupling behavior among three waves. The results indicate that the output can
be fine tuned by the phase and intensity of the control-light.
An advanced design of receiver for free space quantum key distribution system
Show abstract
We presented an advanced design of receiver in free space quantum key distribution (QKD) system based on BB84
protocol. In this system, a novel four polarization beam splitter is used in the receiver. It simplifies the receiver
fabrication process, and the reflection loss is reduced too. Then we built the transmitter and the receiver for QKD system.
The outdoor 200m free space QKD experiment was carried out, the bit error rate is 0.91% when the average photon
number in each optical pulse was about 0.1. This result indicates that our design for the QKD system is feasible.