A novel double-clad As2Se3 chalcogenide photonic crystal fiber is proposed and the slow light via stimulated Brillouin scattering is theoretically investigated. The Brillouin gain spectrum by taking into account the high-order acoustic modes is analyzed. The simulated results indicate that the slow light can be tuned by varying the air filling fraction in the inner cladding. The time delay upto 1120ns can be achieved with 1-m-long fiber when pumped with 10mW. But these features of slow light are less affected with the change of the air filling fraction in the outer cladding.
Intermodal Brillouin frequency shift and Brillouin gain spectrum in few-mode fibers are investigated by full vectorial finite element method, and the influences of pump power on the time delay and pulse broadening factor are also simulated. The simulation results show that Brillouin gain of intermodal stimulated Brillouin scattering varies with different modes pairs. Time delay increases with increasing of pump power. Pulse broadening factors decrease with the input signal pulse width but increase with the input pump power. Optimized results show that time delay of LP01 - LP01mode pair is 213.2ns, and the corresponding pulse broadening factors is 1.126.
In this work, we propose a schematic design for the biochemical sensor, which is based on the polyatomic photonic crystal ring resonator (PCRR). Unlike with the conventional approach, the proposed PCRR is constituted by two different branching waveguides (WG), which are all in the same lattice direction but have different optical propagation properties due to the binary nature of the diatomic square lattice. Electromagnetic analysis via PWE and FDTD numerical techniques are employed to investigate the sensing performance and the results show that the proposed sensor can efficiently detect the small changes in the refractive index of sensing area.
In this work, we propose a new scheme of generating high quality frequency quadrupling signal for millimeter-wave wireless communication system. The frequency quadrupling scheme is achieved by using three parallel Mach-Zehnder modulators (MZMs) and an optical phase shifter. The first two MZMs are driven by the RF signals to operate at the maximum transmission point. The third MZM is operated with no RF signal and an extra π-phase difference is introduced for it by the optical phase shifter. The advantage of the proposed scheme is that the optical carrier and the fourth optical sideband can be suppressed simultaneously. The performance of proposed scheme is investigated theoretically and evaluated by simulations. Numerical results show that the radio frequency spurious suppression ratio (RFSSR) higher than 44.18 dB and the optical sideband suppression ratio (OSSR) higher than 21 dB can be obtained without optical filter when the extinction ratio (ER) of the MZM is 30 dB. The impact of the non-ideal RF driven voltage and phase difference of RF driven signal applied to the first two sub-MZMs on OSSR and RFSSR is also discussed and analyzed.
In this paper, a novel fiber Bragg grating (FBG) sensor which can measure the temperature and strain simultaneously is presented. The cladding layer of the proposed FBG sensor is made of a uniaxial crystal material (LiTaO3) and the electric field is applied on the 1/2 area of the sensor. The sensing performance was investigated by the coupled-mode theory and dual-wavelength method. We found that the strain sensitivity and the temperature sensitivity of the 1/2 area with no electric field are 0.841 pm/με and 14.31 pm/°C respectively. If the electric field is increased from 0 to 400×107 v/m, the temperature sensitivity of this device varies from 14.31 pm/°C to 14.12 pm/°C and its strain sensitivity varies from 0.841 pm/με to 0.850 pm/με. So, the obtained results demonstrate that the simultaneous measurement of temperature and strain can be achieved by using this scheme. The proposed sensor has potential applications in optical fiber sensing systems due to small size, high sensitivity and compatible with optical fiber.
Design optimization of a pure silica dual-core photonic crystal fiber for broadband dispersion compensation is proposed
to match the relative dispersion slope of the standard single-mode fiber. The influence of the three diameters of the
air-holes in the outer cladding upon the dispersive and slope-matched property is investigated and a dispersion value of
-3179.9 ps • ;nm&--1 • km--1 at 1550 nm has been predicted. The dispersion of the standard single-mode fiber, which is
187 times the length of the dual-core photonic crystal fiber, can be compensated (to within 0.12%) over the entire C band
/ (to within 0.56%) over the 100-nm broadband centered at 1550nm .
A new tunable wavelength selector based on the fiber Bragg grating with cladding made of LiNbO3 with optical axis
running along the axis of fiber Bragg grating was investigated. The calculated results indicate that the reflected
wavelength can be tunable from 1550.921 nm to 1548.9668 nm with variation of electric field running along the fiber
axis from 107 to 108V/m, the reflectivity varies from 99.8252% to 99.9715%. The tunable wavelength range will be large
with the electric field increases. These rules indicate that the new tunable wavelength selector based on the fiber Bragg
grating with cladding which is made of uniaxial anisotropic electro-optic crystal material can be achieved through
adjusting the electric field intensity while keeping the fiber grating length, periodicity and the other parameters as
constants.
The reflectivity and the Bragg wavelength of a fiber Bragg grating formed in a photonic crystal fiber with central pure
core defect and a regular hexagonal array of microscopical holes cladding were investigated by the improved effective
index method, the calculated results indicate that the scalar approximation condition will not be satisfied when the filling
factor is more than 0.45, the reflectivity increases from 86.6% to 93.9% with the filling factor increasing, and the Bragg
wavelength decreases from 1550.347nm to 1549.236nm when f <0.53. This rules provided the theoretical basis for
designing new fiber Bragg gratings formed in the PCF.
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