Abstract: In an optical access network architecture based on Dense Wavelength Division Multiplexing (DWDM) a central laser source in the central station provides a large number of wavelength channels. Optical interleavers are then used to partition and finally demultiplex the set of available wavelengths to provide one bi-directional wavelength channel per access node, the central station being the only laser source in this network. The laser source provides a large number of very tightly spaced wavelength channels. Each access node retrieves the laser source from the signal received from the central station to be used in modulating its upstream signals. This access network architecture provides one wavelength channel for each access node, and hence enables protocol and data rate transparency on each channel.

Abstract: A Data Link Control protocol for 3G wireless communication system for direct support for network layer protocols, e.g. the Internet Protocol (IP), is provided. The Link Layer disclosed comprises a Link Access Control (LAC) sublayer and a Medium Access Control (MAC) sublayer. At a transmit end of the wireless system, a plurality of Quality of Service (QoS) data planes are created to directly support the IP QoS. Each QoS data plane is optimized to handle QoS requirements for a corresponding Class of Service (CoS). Data packets received at the LAC sublayer are directed to a QoS data plane according to the particular QoS information they contain and processed according to the particular QoS requirement to generate variable size LAC frames. The variable size LAC frames are transmitted to the MAC sublayer for generating radio link protocol data units (RLP PDUs) to be transmitted to a receiving end.

Abstract: A Data Link Layer (DLL) protocol for direct support of the Internet Protocol (IP) networking in the Universal Mobile Telecommunications System (UMTS), is provided. The disclosed Data Link Layer comprises a Radio Link Control (RLC) sublayer and a Medium Access Control (MAC) sublayer. At a transmit end, as well as at a receiving end of the UMTS wireless system, a plurality of Quality of Service (QoS) planes are created according to IP QoS requirements. At the RLC level, each QoS plane comprises a Data-RLC and a Control-RLC. The QoS planes are optimized to handle the QoS requirements of a corresponding Class of Service (CoS). At the transmitting end, the data packets received from the upper layers are directed to a QoS plane according to the particular QoS information they contain, and processed according to their particular QoS requirement. A Segmentation, Concatenation, and Reframing module (SCR) is used to generate variable size RLC frames, including multiframing.

Abstract: An optical amplifier for two adjacent bands of optical data channels provides gain across the entire spectrum, including the so-called dead-band, by splitting the entire input signal equally into two paths. One path is optimized to amplify one band and the other path is optimized to amplify the other. An optical delay in one path, usually the one optimized for the lower wavelength band, ensures equal optical path lengths for the two paths. The amplified signals in that two paths are then combined to yield or flat gain profile across the two bands and the gap in-between.

Abstract: The present invention introduces a novel and simple method to adjust the MZ filter channels to those of the ITU grid. This is done through inducing an optical path length difference by using a UV light source to create a change in the index of refraction of the fiber arms after the device is packaged. The UV light is launched into the MZI filter through one of its input ports in order to achieve the phase adjustment. Since the exposure length is the entire length of one of the arms of the MZI, the required refractive index change is much smaller than the localized UV tuning of the previous methods. This allows for a weaker UV source power and shorter treatment times, thus reducing the chances of localized fiber damage.

Abstract: A Mach-Zehnder interferometer having two optical couplers interconnected by two optical fibers at least one of which is temperature insensitive. In use, temperature induced changes in the geometrical length and refractive index of the temperature insensitive fibers offset each other so that the optical path length of the fiber is unaffected by the temperature change. Where two temperature insensitive fibers are included these may be of the same or of different lengths. The interferometer may be used in a Dense Wavelength Division Multiplex system.

Abstract: In this invention an optical gain element is used where a fraction of the optical output signal is passed through a periodic filter and fed back to the gain medium. This configuration simply forms a multi-wavelength ring laser. The optical gain element provides the gain medium for the laser and the filter forces the laser to lase on the predetermined wavelengths. The periodic filter can simply be an asymmetric Mach-Zehnder Interferometer (MZI). It is known that asymmetric MZIs have an almost sinusoidal wavelength response where its period is a function of the length difference of the arms of the asymmetric MZI. Therefore, channel spacing may be controlled by changing the arms length difference in an Asymmetric MZI.

Abstract: An optical network having a number of optical amplifiers utilizes the Internet Protocol (IP) to control the amplifiers via the Internet, where optical amplifiers are assigned unique Internet addresses as required.

Abstract: A method of making an asymmetric Mach-Zehnder Interferometer (MZI) adjusts the length of the arms of two Michelson Interferometers, (MI) to achieve desired wavelength response then combines the MIs to provide the MZI. An asymmetric MZI is, therefore, provided which comprises two asymmetric MIs optically connected back-to-back.

Abstract: WDM demultiplexers are provided utilizing, for example, cascaded asymmetric MZI filters, wherein the (asymmetric) differential delay is such that at the output of the first stage MZI demultiplexes the WDM channels in groups of two at its output. The result is a relaxed specification for the frequency response of the filters.