Abstract: An optical amplifier is provided for performing amplification of optical signals of two wavelength bands, where deterioration in the optical SN ratio relative to one wavelength band is reduced, with a simple construction which can deal with restrictions on installation space, power consumption and the like. To this end, the present optical amplifier has a C/L band optical amplifying section for amplifying respective optical signals of a C band and an L band, a demultiplexer for demultiplexing output light from the C/L band optical amplifying section into the C band and the L band, an L band optical amplifying section for amplifying L band optical signals which have been demultiplexed by the demultiplexer, and a multiplexer for multiplexing the C band optical signals which have been demultiplexed by the demultiplexer and the L band optical signals which have been amplified by the L band optical amplifying section.

Abstract: A high-gain, saturated output, double-pass, fault-tolerant optical amplifier has an extended range of stability, output power, and efficiency and fall back modes of operation. The optical amplifier is typically configured in a two-stage polarization maintaining configuration, employing erbium-doped fibers as the gain media in both of the stages. At least one optical element in a loss-insensitive region of the amplifier can have a loss substantially higher than optical elements in the gain paths outside of the loss-insensitive region without substantially reducing the overall output power and efficiency of the amplifier. These elements can influence the amplified signal waveform, spectrum, signal-to-noise ratio, or subsequent performance in an optical network, as well as amplifier characteristics, such as output power, stability, efficiency, and reliability. The optical amplifier is suitable for both free-space and fiber optic network applications.

Abstract: An optical transmission path in a Raman gain module (1) for transmitting signal light input from an input terminal (1a) and Raman-amplifying the signal light by pumping light supplied from pumping light source units (21, 22) is formed by connecting in series two Raman amplification optical fibers (11, 12) having different wavelength dispersion values. According to this arrangement, wavelength dispersion in the amplifier module (1) can be controlled using, e.g., the combination of the wavelength dispersion values of the Raman amplification optical fibers (11, 12). Hence, accumulation of dispersion into signal light and signal light transmission in an almost zero dispersion state are prevented, and degradation in signal light transmission quality due to the nonlinear optical effect is suppressed.

Abstract: The cross phase modulation generated by a fiber amplifier is compensated for by converting the amplitude variations of the wavelength-division multiplex signal (WMS) into an electrical signal which controls a phase modulator (2) in such a manner that the signal distortion caused by cross phase modulation is compensated for.

Abstract: The present invention relates to an optical transmission line enabling Raman amplification of an optical signal when pumping light is supplied thereto, a method of making this optical transmission line, and an optical transmission system using this optical transmission line. This optical transmission line is an optical transmission line enabling Raman amplification of an optical signal when pumping light is supplied thereto, wherein a region yielding the maximum value of Raman gain coefficient is separated from an end portion where the pumping light is supplied by a predetermined distance along a direction in which the pumping light advances.

Abstract: A laser transmitter capable of transmitting large numbers of WDM channels but requiring locking of only a single channel. Each of the channels can be individually modulated using an external modulator.

Abstract: In a method of amplifying optical input signals over a wide bandwidth, the optical input signals are applied to an optical waveguide made from a rare-earth-doped amorphous material (e.g., erbium-doped yttrium aluminum oxide material). The optical input signals include optical signals having wavelengths over a range of at least 80 nanometers, and, preferably, over a range of at least 160 nanometers. Pump light is applied to the optical waveguide to cause the waveguide to provide optical gain to the optical input signals. The optical gain causes the optical signals to be amplified within the waveguide to provide amplified optical signals over the extended 80-160-nanometer range, including, in particular, optical signals having wavelengths at one end of the range and optical signals having wavelengths at a second end or the range.

Abstract: A multi-port optical amplifier chip has an inner cladding layer sandwiched between a pair of outer cladding layers, a plurality of active core elements disposed substantially within the inner cladding layer to receive optical signals at respective input ports and transmit amplified optical signals at respective output ports, a pair of reflecting surfaces on opposing sides of the inner cladding and at least one pump source. The pump source directs pump light into the inner cladding layer where it is confined to bounce back-and-forth across the active core elements thereby enhancing the absorption of pump light into the core elements, hence increasing gain. Greater than 5 dB over the C-band (1930 nm-1965 nm) in less than 10 cm is expected with a phosphate glass material co-doped with greater than 2 weight percent Erbium and 10 weight percent Ytterbium. A number of fiber drawing based approaches are contemplated for manufacturing the amplifiers to achieve this performance and reduce cost.

Abstract: Raman amplification pumping light output from a pumping light source unit is supplied to a Raman amplification optical fiber through an optical circulator. The remaining Raman amplification pumping light is detected by a light-receiving element through an optical circulator and bandpass filter. Signal light that has reached a Raman amplifier propagates through the Raman amplification optical fiber while being Raman-amplified. A control section controls the power or spectral shape of Raman amplification pumping light output from each of N pumping light sources included in the pumping light source unit on the basis of the power of the remaining Raman amplification pumping light, which is detected by the light-receiving element. Hence, a Raman amplifier capable of easily controlling gain spectrum flattening in the signal light wavelength band can be obtained.

Abstract: An optical amplifier arrangement having at least one optical amplifier stage (V1, V2) and a variably settable attenuator (VDL), whose attenuation spectrum (DV2, DV3, DV5, DV6) assumes an attenuation profile (DV2, DV3, DV5, DV6) that increases or decreases proportionally to wavelength. To reduce tilt of the channel level spectrum of an optical transmission signal, the profile of the attenuation spectrum (DV2, DV3, DV5, DV6) is variably settable. An advantageous structure of the variably settable attenuator according to the invention is furthermore specified.

Abstract: This invention provides a gain control device and method for an erbium doped fiber amplifier that is capable of maintaining a constant gain irrespective of the intensity variation of the input signal light.

Abstract: An improved optical power transient control scheme is provided for optical amplifiers used in long haul, high capacity DWDM optical networks. The optical power transient control scheme employs a combination of feed-forward and feedback control mechanisms to adjust the pump laser current of an amplifier. In this way, the optical power transient control scheme allows for very fast detection of transient changes in optical input power and fast control settling time with minimal optical power degradation.

Abstract: The invention is directed to providing a characteristic measuring method and characteristic measuring system of a WDM optical amplifier that enables high speed and accurate measurement of characteristics of an optical amplifier by a measuring system with a simple construction. To this end, with the characteristic measuring method of a WDM optical amplifier according to the invention, for example, a plurality of signal lights corresponding to respective signal light wavelengths in a measurement wavelength band are divided into groups for odd and even channel numbers, such that signal lights of adjacent wavelengths are in different groups, and the power of each signal light is adjusted such that the total power of the signal lights in each group is approximately equal to a preset reference value. Then, a WDM signal light containing the multiplexed signal lights is in turn input to the optical amplifier, and the spectrum of the output light spectrum the optical amplifier is input for each group.

Abstract: A system and method for controlling alignment of laser center wavelengths and filter passband center wavelengths in optical amplifiers for purposes of providing automatic gain control and eliminating unwanted noise. The system and method exploits a wavelength-locked loop servo-control circuit and methodology that enables real time mutual alignment of a laser pump signal having a peaked spectrum function including a center wavelength and a wavelength selective device such as an optical filter implementing a peaked passband function including a center wavelength in an optical amplifier.

Abstract: An optical amplifier array is integrated with a switching matrix with a tunable filter. As a result, switching and amplification can be performed in a common hermetic package, for example, thus offering advantages associated with small footprint and low cost. The optional integration of the tunable filter, with or without the switching matrix, further allows for the monitoring of the separate optical links to ensure the proper routing of signals and/or proper spectral slotting of the various channels in each of the WDM optical signals.

Abstract: Optical signals (multi-wavelength light) are guided to an EDF. The EDF is supplied with pump light generated by a first and a second pump light sources. Dummy light is generated by a dummy light source and supplied to the EDF. The wavelength of the dummy light is shorter than a wavelength range in which the optical signals are allocated.

Abstract: An optical sending apparatus of this invention includes a plurality of optical signal generating sections, a dispersion compensating section and a wavelength multiplexing section. The dispersion compensating section performs compensation with a predetermined chromatic dispersion value to at least one of polarized light generated by the optical signal generating sections while a predetermined state of polarized light is maintained. The wavelength multiplexing section combines output light outputted from the optical signal generating section with output light passing through the dispersion compensating section so that the polarized light of adjacent wavelengths crosses orthogonal to each other. The optical sending apparatus having such a construction can generate high-density WDM optical signals, the dispersion of which is compensated in advance, by a polarization crossing method.

Abstract: An arrangement for monitoring the performance of each pump source in a fiber Raman amplifier arrangement utilizes a set of unique “signature” signals, each signature signal impressed on a different pump input signal. At the receiver, the signature signals are extracted from the received, amplified signal. If a particular signature signal is missing at the receiver, this is indicative of failure of its associated pump source at the transmitter. If a particular signature signal is noticeable weaker than other received signature signals (as evidenced by, for example a low SNR or high BER), this is indicative of a power loss in its associated pump source. Since each signature signal is chosen to be unique, the identity of each pump source can be easily ascertained. In one embodiment, a low data rate signal is impressed on an RF signal used to modulate the pump prior to be applied to the transmission fiber.

Abstract: A broad bandwidth optical amplifier (50) includes an optical pump source (52). A Raman chamber (56) is coupled to an output (54) of the optical pump source (52). An optical fiber ring (62) having a first end (64) is coupled to a first end (66) of the Raman chamber (56). A second end (60) of the optical fiber is coupled to a second end (58) of the Raman chamber (56). A doped optical fiber is coupled to a second end of the optical fiber ring. The Raman chamber produces a number resonant Raman stokes lines.

Abstract: A Raman fiber amplifier includes: a transmission fiber; at least one optical pump providing optical pump power to the transmission fiber; and at least one pump power detector; at least one signal detector detecting signal power propagating through the transmission fiber. The Raman fiber amplifier also includes a controller that adjusts the pump power provided by the pump to adjust, gain, or signal power provided by this Raman fiber amplifier.