Abstract: The system includes a receiver for receiving a bit stream; an error monitor for indicating a first error rate for a first set of data received in the bit stream; and an adjustable circuit for converting an incoming signal into the bit stream using a reference signal that is modulated using a control signal. The system also includes a subsystem for correlating the first error rate and the control signal to generate the reference signal. The control signal has an amplitude that is selected so that a second set of data received in the bit stream has a second error rate that is less than the first error rate.

Abstract: A connectionless packet network and an optical WDM network are interconnected by one or more optical interface modules (gateways) that include both optical to electrical interfaces, as well as a connection management module, or control element, that is arranged to control the OADM's and the configuration of lasers and port assignments within the gateways, such that a route through the optical network to a desired endpoint is selected. The OADM's can be programmed, (i.e., locally or remotely controlled by the control element) such that the wavelengths that can be added or dropped by an OADM can be changed, thereby allowing routes to be established through the optical network, from an originating gateway to a destination gateway. In addition, the optical interface modules can include a plurality tunable lasers that can be controlled such that routes can be established through the optical network without requiring changes to the routing table that associates particular endpoints with particular ports.

Abstract: A fiber-optic WDM ring carries communication traffic among a plurality of nodes, each node associated with respective subscriber premises. Remote gain is provided in at least one link of the ring. In specific embodiments of the invention, the remote gain is applied preferentially to those wavelength channels most in need of amplification. In specific embodiments of the invention, the remote gain is Raman gain.

Abstract: A fiber-optic WDM ring carries communication traffic among a plurality of nodes, each node associated with respective subscriber premises. The WDM ring includes an optical add-drop module (OADM) at each node for adding and dropping signals associated with that node. The WDM ring also includes active terminal equipment at each node for conditioning incoming and outgoing data and for converting between the optical and electrical domains. The OADM at each of at least some nodes, to be referred to as enhanced nodes, is situated at a site physically separated from the powered terminal equipment, and is coupled to the powered terminal equipment via an optical medium. At each enhanced node, traffic not destined for that node is routed through no more than one enclosure on subscriber premises that requires a connection. If there is such enclosure, it contains the OADM.

Abstract: An optical add-drop module (OADM) includes in the through-path exactly two thin-film filters (TFFs) having respective passbands that approximately coincide in wavelength. Each TFF has a respective across-the-band isolation level, representing the smallest isolation achieved at any wavelength within the passband. The respective reflection characteristic curves of the two TFFs are at least partially complementary, such that the OADM isolation level exceeds the logarithmic sum of the across-the-band isolation levels of the respective TFFs.

Abstract: A tunable semiconductor laser comprises a gain section having an MQW active region, a uniform pitch grating DFB region, and first waveguide. A composite reflector, including a second MQW region and a second waveguide, forms a cavity resonator with the DFB region. A tuning voltage applied to the composite reflector induces refractive index changes, thereby allowing the center wavelength to be altered.

Abstract: A tunable chromatic dispersion compensator for optical communication systems is disclosed. An optical grating, such as a fiber Bragg grating, non-chirped, linearly chirped or non-linearly chirped, is coated on its outer surface with a coating have a variable diameter and strained is applied to the fiber. The fiber may be latchably strained so that the grating characteristics may be changed or tuned while avoiding use of a continuous power supply. Various optical networking applications using such dispersion compensating devices are also disclosed.

Abstract: A method for making a chirped grating device capable of a broad bandwith for optical communication systems is disclosed. An intrinsically-chirped optical grating is externally strained to alter the range of chirping. The external strain may be induced by a gradient-generating body bonded onto the length of the fiber grating that may be latchably strained so that the grating characteristics may be changed or tuned while avoiding use of a continuous power supply. Various optical networking applications using such dispersion compensating devices are also disclosed.

Abstract: A tunable semiconductor laser comprises a gain section having an MQW active region, a uniform pitch grating DFB region, and first waveguide. A composite reflector, including a second MQW region and a second waveguide, forms a cavity resonator with the DFB region. A tuning voltage applied to the composite reflector induces refractive index changes, thereby allowing the center wavelength to be altered.

Abstract: A tunable chromatic dispersion compensator for optical communication systems is disclosed. An optical grating, such as a fiber Bragg grating, nonchirped, linearly chirped or non-linearly chirped, is strained to alter the dispersion compensator characteristics, preferably with a gradient-generating body bonded onto the length of the fiber grating. The body may be latchably strained so that the grating characteristics may be changed or tuned while avoiding use of a continuous power supply. Various optical networking applications using such dispersion compensating devices are also disclosed.

Abstract: A programmable and latchable device for wavelength shifting and chromatic dispersion compensating is disclosed. An optical grating such as a Bragg grating, a nonchirped grating, or a linearly or non-linearly chirped grating, is magnetostrictively strained to alter the dispersion compensator characteristics. In a preferred embodiment, a gradient magnetostrictive body is bonded along its length to the fiber grating. In yet another preferred embodiment, a magnetostrictive body is bonded onto the length of the fiber grating, and a gradient generating, programmable and latchable magnet component is placed adjacent the magnetostrictive body. The body is then latchably strained to a desired level by controlling the extent of magnetization in the magnetostrictive material and the magnet so as to induce or enhance chirping characteristics in the grating. Various optical applications using such are disclosed.

Abstract: A tunable semiconductor laser comprises a gain section having an MQW active region, a uniform pitch grating DFB region, and first waveguide. A composite reflector, including a second MQW region and a second waveguide, forms a cavity resonator with the DFB region. A voltage applied to the composite reflector induces a quantum confined stark effect, thereby allowing the wavelength to be altered. In one embodiment, the current drive to the active region and the shape of the first waveguide (e.g., a raised-sine function) are mutually adapted so that N longitudinal modes have essentially the same threshold gain and so that the DFB region spanned by the first waveguide is segmented into N zones, each zone providing optical feedback at a different wavelength corresponding to a different longitudinal mode.

Abstract: In a WDM fiber-optic network, a unique laser transmitter enables signals to be routed at three hierarchical levels: at one level discrimination among signal paths is based on N WDM wavelength channels, at another level discrimination is based on m AM subcarrier frequency channels, and at a third level discrimination is based on n FM subcarrier frequency channels. Thus, a total of Nmn distinguishable optical channels can be accommodated and a like number of users served. The laser transmitter comprises a broadband, tunable semiconductor laser which includes an intracavity, integrated composite reflector to which a tuning voltage and a FM dither signal are applied, an intracavity gain section to which drive current is applied, and an extracavity, integrated electroabsorption modulator to which an information (e.g., data, voice, video) signal and an AM dither signal are applied.

Abstract: In accordance with the present invention, an optical fiber communications system is provided with an adaptive data equalizer to correct for linear disortion of signals transmitted over optical fibers. A feedback signal from a receiver is used to custom tailor the spectral profile of a launched pulse to thereby minimize the distortion of a received pulse. The system uses optical taps for feedback control in order to adapt to changing conditions in the fiber path.

Abstract: A tunable semiconductor laser comprises a gain section having an MQW active region, a uniform pitch grating DFB region, and first waveguide. A composite reflector, including a second MQW region and a second waveguide, forms a cavity resonator with the DFB region. A tuning voltage applied to the composite reflector induces a quantum confined stark effect, thereby allowing the center wavelength to be altered. A pre-chirp signal applied the composite reflector reduces signal distortion in fiber optic systems.

Abstract: A tunable semiconductor laser comprises a gain section having an MQW active region, a uniform pitch grating DFB region, and first waveguide. A composite reflector, including a second MQW region and a second waveguide, forms a cavity resonator with the DFB region. A tuning voltage applied to the composite reflector induces refractive index changes, thereby allowing the center wavelength to be altered. A dither signal applied the composite reflector broadens the spectrum of the laser output, thereby reducing SBS in fiber optic systems.