Abstract: In the system of the present invention, two DFB laser outputs are combined in a first stage to produce a beat signal. The two main channels interfere with each other to form beat signals. This combined signal is then used as the seed to create multi-channels through optical fiber non-linearity in a multiplier stage.

Abstract: New systems and methods for wavelength locking for a class of multi-wavelength laser sources (MWLS) are provided. In this type of MWLS, the set of output wavelength channels are produced from a limited number of initial laser sources, such as a single laser or dual laser. In this invention, the initial lasers are locked based on the wavelengths of the outer channels in the set of output channels to provide tighter channel locking than that of a single laser source. This is mainly possible since the error in channel spacing caused by channel wavelength offset of the seed lasers is amplified by channel multiplication done in MWLS. This provides better resolution than applying wavelength locking to the seed lasers.

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 the present invention a Multi-Wavelength Ring Laser Source (MWRLS) design based on Erbium Doped Fiber Laser is provided. A LiNbO3 modulator is used to extend laser channels and as mode-locking device.

Abstract: In the system of the present invention, two DFB laser outputs are combined in a first stage to produce a beat signal. The two main channels interfere with each other to form beat signals. This combined signal is then used as the seed to create multi-channels through optical fiber non-linearity in a multiplier stage.

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: 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: 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.

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.