To meet the application demand of optical communication system, a new type of variable optical power splitter (VOPS)
based on slot waveguide by adjusting manually is proposed in this paper. The device is designed by using the principle
of optical field effect. It has an import port which provides import power, and two output ports, the power of which is
divided dynamically by changing the width of the gap between two slot waveguides. This paper can specify the
operation principle of the device, test its important technical indicators and analyze experimental datum. Experimental
results show that the device can realize light distribution of the single wavelength and multiple wavelengths and that the
power splitting ratio is dynamically tunable and the tuning range can be 1-25dB, which ensures rapid organization and
deployment of communication network.
With the development of optical communication technology,
all-optical network is promising in next generation
networks. Characterized by good transparency, wavelength routing, compatibility and scalability, all-optical network has
become the most promising candidate for future high-capacity network. And reconfigurable optical add/drop multiplexer
(ROADM) has been regarded as one of the key equipments of the intelligent WDM optical communication network. In
this paper, we compare several design methods of ROADM, and introduce the design and implementation of ROADM
based on fiber Bragg grating (FBG) and optical switch (OSW). We also propose the new idea of FBGs OSW composed
OSW and FBG collimator, which is the integration package of FBGs and collimator. Benefited from the filter
characteristics of FBGs and the selectivity of OSW, the performance of ROADM can be optimized. In addition, the
ROADM has been tested and analyzed.
This paper discusses the excursion mechanism of transient in the EDFA and the corresponding impairments to the DWDM. The dynamic amplifier simulation model and simulation results are presented. The technical platform for next-generation intelligent EDFA is introduced and realized. The method is demonstrated to be feasible by the experimental results.
Quantum key can be theoretically demonstrated to be secure and now commercially available. The bit rate of the quantum key distribution is much lower than that for "one-time pad" needs. The practical bit limitation of the quantum key distribution system is analyzed to explain necessity for bit amplification. The method of bit amplification is also introduced in this paper.
The characteristics of uniform fiber Bragg gratings (FBGs) is analyzed. The reflected spectra in apodized uniformly periodic FBGs are calculated and the double exposure technique is used in suppressing the sidelobes of uniform gratings. After that, the corresponding FBGs filters used in DWDM networks and systems are imprinted. Based on the apodized FBGs, a cascaded FBGs filter module is proposed, in which two, or more, pieces of identical FBGs, with the same central wavelength, same bandwidth and same reflectivity, are spliced in series and each FBG is equipped with tuning device. By controlling the tuning device, the module can act either as a tunable single channel filter with its central wavelength and/or bandwidth being tunable, or as a double channel filter with its central wavelength being tunable. The tested results demonstrated that the module can dynamically tuned in the range of several nanometers.
For the application in Passive Optical Network (PON), a novel design of OCDMA system scheme is proposed in this paper. There are two key components included in this scheme: a new kind of OCDMA encoder/decoder system based on TCM and FFH and an improved Optical Line Terminal (OLT) receiving system with improved anti-interference performance by the use of Long Period Fiber Grating (LPFG). In the encoder/decoder system, Trellis Coded Modulation (TCM) encoder is applied in front of the FFH modulator. Original signal firstly is encoded through TCM encoder, and then the redundant code out of the TCM encoder will be mapped into one of the FFH modulation signal subsets for transmission. On the receiver (decoder) side, transmitting signal is demodulated through FFH and decoded by trellis decoder. Owing to the fact that high coding gain can be acquired by TCM without adding transmitting band and reducing transmitting speed, TCM is utilized to ameliorate bit error performance and reduce multi-user interference. In the OLT receiving system, EDFA and LPFG are placed in front of decoder to get excellent gain flatness on a large bandwidth, and Optical Hard Limiter (OHL) is also deployed to improve detection performance, through which the anti-interference performance of receiving system can be greatly enhanced. At the same time, some software is used to simulate the system performance for further analysis and authentication. The related work in this paper provides a valuable reference to the research.
A new type of CATV network management system developed by universal MCU, which supports SNMP, is proposed in this paper. From the point of view in both hardware and software, the function and method of every modules inside the system, which include communications in the physical layer, protocol process, data process, and etc, are analyzed. In our design, the management system takes IP MAN as data transmission channel and every controlled object in the management structure has a SNMP agent. In the SNMP agent developed, there are four function modules, including physical layer communication module, protocol process module, internal data process module and MIB management module. In the paper, the structure and function of every module are designed and demonstrated while the related hardware circuit, software flow as well as the experimental results are tested. Furthermore, by introducing RTOS into the software programming, the universal MCU procedure can conducts such multi-thread management as fast Ethernet controller driving, TCP/IP process, serial port signal monitoring and so on, which greatly improves efficiency of CPU.
Nowadays, EPON technology is regarded as one of the best candidate technology for next generation broadband access technology. In this paper, the architecture of EPON is introduced first. The upstream in EPON adopts TDMA/TDM technology, and it is necessary to know the exact RTT(Round Trip Time), the principle of RTT measurement (ranging) and RTT compensation are introduced. We use Xilinx FPGA SpartanII chip series to realize ranging function module, the main idea of implementation is given in this paper, and this can be used for further study of hardware implementation.
The excursion mechanism of transient in the EDFA is analyzed and the corresponding impairments to the DWDM are discussed. Based on the analysis and the discussion, an experiment is designed to reduce the transient by pump controlling and the method is demonstrated to be feasible by the experimental results.
As one of the most important properties in fiber Bragg gratings (FBGs), the reflected spectra of FBG have been attractive research subjects. However, the issue of non-reciprocity of reflected spectra in the grating has not be addressed. We observed the phenomenon of non-reciprocity in uniform FBGs in our experiment and in this paper make a preliminary analysis and calculation of the reflected sprectrum non-reciprocity in a uniform FBG
The present status of the use of fiber-free optics technology for solutions providing high speed local access connectivity is introduced. The advantages of the technologies are presented. By analyzing the factors that limit the public application of the free-space optics, an integrated network solution that combines the benefits of both microwave technology and free-space technology is presented.
We have reviewed some techniques which are used in supervision of EDFAs so far. Based on these techniques, we propose a new supervisory scheme and discuss some key problems in the scheme. This kind of SV system will be quite important for the all-optical networks in the future.