A single device which can demodulate both DPSK and DQPSK formats by simply rotating a quarter-wave plate
is proposed in this paper. Through introducing LC phase retarder and polarization-dependent phase
compensation, fast tuning time of 50ms and low PDFS of less than 300MHz are successfully realized.
We theoretically and experimentally report a single-wavelength module of 1x4 wavelength selective switch (WSS)
module based on the bi-axial MEMS mirror and thin film filter technology. With a cascaded structure of such WSS
module, a novel 1xN WSS can be realized. The insertion loss of 3dB, extinction ratio > 50dB and hitless switching are
In this paper, we theoretically and experimentally introduce a new reconfigurable optical add/drop multiplexers
(ROADM) module which bases on the narrow-band optical switch (NBOS) technology and achieves the narrow-band
optical switching with a Fabry-Perot cavity. In comparison with the analysis of the current ROADM technologies, the
NBOS-based ROADM module is proven to be cost-effective, low insertion loss, narrow-band, and has a more mature
technology. It would grow to be a cost-effective ROADM solution than any of the others.
The impacts of polarization dependence loss (PDL) on the polarization mode dispersion (PMD) compensation in
return-to-zero (RZ) and non-return-to-zero (NRZ) modulated systems are discussed in this paper. PDL affects the degree
of polarization (DOP) feedback PMD compensation only in the presence of PMD. And in the presence of PMD and PDL,
DOP relates not only to both the PMD and the PDL vectors, but also to the signal's polarization states. In the presence of
PDL, DOP-feedback PMD compensation would be more effective in NRZ system than in RZ system.
A novel polarization dependence loss (PDL) measurement approach using the degree of polarization (DOP) feedback
signal has been introduced in this paper. Both the theoretical analysis and the experimental simulation show that, while
maintaining a very acceptable level of measurement accuracy, this PDL measurement method could effectively reduce
the measurement time. In comparison with the current PDL measurement technologies, the most prominent property of
our method is that it could provide different PDL measurement accuracy and range by changing the value of polarization
mode dispersion (PMD) element in the measurement setup.
In this paper, a modified stacking method to fabricate photonic crystal fibers with squeezed lattice is presented, for the first time to our knowledge. This modified method can realize different structures of photonic crystal fibers with different expected squeezing ratios. The influences of the structural parameters on the squeezing ratio and birefringence are separately discussed in detail. Moreover, the birefringence characteristics of such photonic crystal fibers are simulated by using supercell lattice method.
In this paper, several triangular-lattice highly birefringent PCFs are analyzed on the base of the full vector model. Several properties of them, such as the PCF's modal field, the birefringence and the dispersion, are simulated by the supercell lattice method. Moreover, a comparison is made among them to study the impact of air-holes configuration of PCFs on their propagation properties. The simulation results show that air-holes at different position have different impact on the propagation properties of PCFs.
The impact of polarization dependence loss (PDL) on the degree of polarization (DOP) feedback signal in polarization mode dispersion (PMD) compensation is discussed in this paper. PDL affects DOP only in the presence of PMD. And in the presence of PMD and PDL, DOP relates not only to both the PMD and the PDL vectors, but also to the signal's polarization states. The PDL minimum endangering PMD compensation is determined by the step size of the practical PMD compensating algorithm, and the DGD value in optical fiber systems. DOP could no longer act as the feedback signal in PMD compensation unless PDL in the fiber system has been effectively eliminated before PMD compensation.
A CCD signal acquisition system featuring a flexible and compact (Charged-Coupled Device) CCD driving mode based on a DSP device is designed for a new developed optical performance monitor (OPM) module. The design has prominent advantages, such as less power consumption, fewer and cheaper attached components and flexibility. The DSP-based system aims to implement the high accuracy conversion from successive video output signals of a CCD device to DSP Processor with least additional circuit components.
A method for calculating the optical-signal-to-noise ratio (OSNR) of an optical performance monitor (OPM) is discussed. OSNR is one of the most import parameters determining DWDM system performance because of its dominance in determining the bit-error-rate (BER). However for the optical and electric components’ limitations, most OPMs are less accurate and dynamic range in measuring OSNR. In order to improve OSNR, heightening measuring accuracy of the signal power and the noise power are both required. The method for improving accuracy of measuring the signal power, namely Gauss Fitting, can heighten the signal power in the selected bandwidth by 1-2 dB. For improving accuracy of measuring the noise power, a kind of algorithm about deconvolution and signal recovery is discussed, which is used to sharpen the signal figure and eliminate effect of signal power to noise power (named cross talk). After deconvolution, the power of the pits of a 100 GHz channel signal can be depressed by 6-8 dB. In conclusion, a research on how to calculate OSNR in the OPM is discussed. By Gauss Fitting and deconvolution, the signal can be recovery efficiently and the result of OSNR can be heightened by 7-10 dB.
A new beam shaping method using cylindrical lensed fiber to change a beam with uniform angular divergence into an elliptical collimated beam with specific size is presented. One structure of the mechanical setting according to the beam shaping method is also provided.
The theoretical model of DOP degraded by PMD is presented, with which one can analyze and maximize DOP directly from two factors, the magnitude and the direction of the PMD vector. According to this, one method to counteract PMD of the link is adjusting the compensating vector’s magnitude to achieve a zero-magnitude total PMD vector in the system, another is changing the vector’s direction adaptively to make the input signal align with the total PMD vector. Further, the NRZ signal DOP property degraded by PMD and the system’s BER against the change of PMD are obtained in the first experiment, also, the PMD compensation performance-degradation as the scrambling rate is increased is studied in the second experiment, in which it is concluded that the scrambling rate of polarization state has an important impact on a reliable, repeatable PMD compensation in a reasonably short time.