Abstract: The invention provides a wavelength-controlled pump MOPA laser and a method of operation thereof. A monolithic semiconductor MOPA laser chip has a DFB-laser based MO (master oscillator) and PA (power amplifier) sections formed in a same monolithic waveguide, and separate MO and PA electrodes for individual control of current injection into the MO and PA sections. The laser wavelength is defined by the DFB grating and is kept fixed by suitably controlling the MO current to compensate for a thermal crosstalk from the PA section, or tuned by suitably changing the MO current or direct heating of the DFB region.

Abstract: A change in loading conditions of fiber amplifiers in an optical communications network causes rapid variations in the gain profile of the amplifiers due to spectral hole burning and stimulated Raman scattering. An apparatus for reducing such gain profile variations is described which monitors optical signal perturbations and reacts by adjusting pump powers of the amplifiers and, or fast variable optical attenuator according to a pre-determined function stored in the form of constants in controller's memory. The optical signal is monitored as total power, and the power of light after passing through one or more optical filters. The light detection is relatively fast, whereby the gain profile variations are compensated by fast controlled variable optical attenuator and pump power adjustment upon the change in loading conditions.

Abstract: Direct pin attachment is the most compact method to connect the OSA and the PCBA, due to better performance in general and allows maximum PCBA space for more functionality. However, direct pin attachment can result in concentrated stress in the OSA-PCBA joint area, which can affect the reliability and yield of the module. To overcome the problem, an integrated transceiver cage and housing is provided including a direct pin attachment with reinforcing tabs, which are fixed to the PCBA prior to the pins to transfer any stress between the OSA and PCBA, thereby reducing the amount of stress applied to the pins.

Abstract: An optical power monitoring device includes a photodetector disposed in close proximity to the cladding of an optical fiber for measuring Rayleigh scattered light from the core of the optical fiber. To ensure only Rayleigh scattered light is measured, a cladding stripper is provided to remove any cladding light prior taking a reading with the photodetector.

Abstract: An optical interferometer for demodulating a differential phase shift keying optical signal includes a planar lightwave circuit and at least one free space delay line optically coupled to the planar lightwave circuit. The planar lightwave circuit has a waveguide splitter, a waveguide coupler, and a phase adjuster. In operation, the splitter splits the optical signal into equal portions, the phase adjuster adjusts the relative phase of the optical signal portions, and the free space delay line provides one-bit delay between the portions of the optical signal. The delayed signals are mixed in the waveguide coupler. The free space delay line can be made variable for adjustment of the bit delay for operation at different bit rates, and/or for optimization of the interferometer performance.

Abstract: A lasing wavelength of a laser diode is determined by applying a forward current to the p-n junction of the laser diode and measuring a voltage across the p-n junction. The lasing wavelength can be determined by performing a simple wavelength calibration of the laser diode. This allows one to stabilize the lasing wavelength, and also to use the laser diode as a reference wavelength source.

Abstract: By steering wanted diffraction orders within a concentrated angular region and steering all unwanted diffraction orders outside that region, a wavelength selective switch achieves high port isolation and densely spaced ports. N inputs receive an optical signal. Optics spatially separate and direct wavelength channels from the signal. A phased array switching engine comprising cells steers a wanted diffraction order of each spatially separated wavelength channel from each cell at an angle within a concentrated angular region relative to the PASE, and steers all unwanted diffraction orders of spatially separated wavelength channels from cells outside the concentrated angular region. Optics direct each wanted diffraction order to one of N outputs in accordance with the steering of the wanted diffraction orders by the PASE. The concentrated angular region is defined by a largest and smallest steering angle wherein the largest steering angle is a margin less than the smallest steering angle.

Abstract: Systems and methods for analyzing the performance of a digital network include capturing a stream of digital data, e.g., interne protocol (IP) packets, that represent streaming video, identifying which of the IP packets include bit errors, determining to which of a plurality of pixels the IP packets including bit errors belong and identifying such pixels as corrupted pixels, and illuminating only the corrupted pixels on a display of a tool. Corrupted pixels in different time blocks can be displayed with different colors to gain a better appreciation of the bit error rate over time.

Abstract: The present invention relates to the use of RFID technology to identify specific cables in a bundle, and in particular to a cable identification device in which RFID devices are connected to the far end of a plurality of cables and splitters, and an RF measurement device is used to identify each cable from the central location. The RF measurement device provides the AC RF electrical signal power required to pass through the at least one AC couple splitter to operate the plurality of RFID devices, and includes means to identify the unique identification numbers associated with the plurality of coaxial cables from the plurality of identification signals received simultaneously.

Abstract: A wavelength selective switch includes a light input/output unit that includes an input unit and an output unit of a wavelength multiplexed light arranged in a form of an array in a first direction, a light dispersing unit that receives the wavelength multiplexed light from the input unit and disperses the wavelength multiplexed light into signal wavelengths, a light condensing element that condenses the light dispersed into the signal wavelengths, and a light deflecting element array that deflects a signal light in the first direction and a second direction, that is orthogonal to the first direction, so as to switch the light of the signal wavelengths condensed by the light condensing element to a desired output unit.

Abstract: A light source including a laser diode, and a method of operating a light source including a laser diode are disclosed. A driving current of the laser diode is dithered to cause a near-field light intensity distribution at an end facet to be perturbed, thereby reducing a time-averaged local intensity of the laser light at the end facet of the laser diode. The reduced time-averaged intensity reduces a possibility of a damage of the end facet.

Abstract: The invention relates to a method for auto-configuring a wavelength selective switch (WSS) device having an output port and a plurality of input ports and coupled to a WSS controller. When connected to a WDM optical network, the WSS controller is programmed to utilize one or more optical channel monitors (OCM) coupled to the input and/or output ports to detect which of the wavelengths are present at the input ports. Wavelengths that are not detected on any input port are blocked by the WSS. Any wavelength detected as present at one and only one input port is switched by the WSS to the output port. If a wavelength is detected at two or more input ports, it is either blocked by the WSS at each of the input ports until user intervention, or is blocked at all but one of the input ports as defined by assigned port priorities.

Abstract: The invention provides fiber-optic light sources such as cladding-pumped master oscillator—power amplifier (MOPA) systems which use double-clad optical fibers (DCF). The inner cladding of the first DCF used in the master oscillator section has a circular cross-section in order to enable the formation of low loss optical splices in the integrated MOPA structure. The inner cladding of the second DCF in the output amplifier section has a shaped non-circular cross-section in order to enhance the absorption of the pump light in the doped core of the second DCF.

Abstract: Downstream channel parameters of a cable network are displayed in graphical form as a function of the channel number or center frequency. Such parameters, including digital channel demodulation parameters, may be plotted concurrently as frequency spectra, revealing frequency signatures of particular network impairments. Frequency spectra of MER, BER, IUC, carrier level, and in-band spectral response may be plotted concurrently in various combinations, providing a concise summary view of a condition of a downstream path at a particular location in the network.

Abstract: Apparatus and method are provided for obtaining an upstream signal spectrum as it was during a time of transmission of a received upstream data packet. The apparatus includes an analog-to-digital converter (ADC), a packet detector coupled to ADC, and a spectrum calculation unit coupled to the ADC and the packet detector. In operation, the spectrum calculation unit computes a spectrum of the digitized upstream signal as it was between the start and end times of the first packet. As a result, the obtained spectrum is representative of a condition of the transmission path during transmission of the upstream data packet.

Abstract: Improved brightness and feedback multi-emitter laser diode modules and methods are provided. A plurality of laser diode emitters emit broad-area light beams in a beam direction. In cross-section, each beam is broad in its slow axis and narrow in its fast axis. Groups of downstream optical components collimate, shape, stack and direct the beams along a light path towards a beam spot (which may be fiber-coupled). After collimating, stacking and directing, the beams are Fourier transformed in the fast-axis through a lens feature having a fast-axis focal length less than about 3 millimeters. In some embodiments, the fast-axis focal length is between about 0.1 and 2.0 millimeters. Astigmatism may be introduced between the fast axis and the slow axis in the beams upstream of the lens feature and in accordance with the fast axis focal length of the lens feature. The emitters may receive feedback including wavelength locking feedback.

Abstract: A high field of view, low height package and wafer-level packaging process are provided. The top surface of a first wafer has recesses defined by sidewalls, with a reflector, and a floor. The reflector is incident a horizontal light path form an edge-emitting diode on the floor, directing the light path vertically. A second optically diffusing wafer receives the vertically directed light. A vertical ring to surround each recess is wafer-level fabricated on one of the wafers. The vertical ring may have a high aspect ratio to increase light diffusion. The second wafer is connected above the first such that each vertical ring encloses its corresponding recess and such that the light vertically exits the optically diffusing media after spanning the height of the vertical ring. Diode electrical connections are provided for externally controlling the diode. Individual packages are separated by double-dicing the connected wafers between the recesses.

Abstract: A method and system for determining a number of load coils in a transmission line are provided. An impulse response of the transmission line is calculated from a characteristic impedance of the transmission line. A number of complex conjugate pole pairs of a transfer function of the impulse response is then determined. Thereby, the number of load coils in the transmission line, which is equal to the number of complex conjugate pole pairs, is determined.

Abstract: An apparatus for enriching data records based on messages monitored on a telecommunications network having an Internet Protocol (IP) portion includes a data record enrichment module for receiving data records from a data record builder. The data records include at least a subscriber identifier field and a handset type identifier field and the data enrichment module stores a table mapping subscriber identifiers with the handset type identifiers. When a received data record includes a subscriber identifier and a handset type identifier, the table is updated appropriately and when the received data record includes the subscriber identifier but does not include the handset type identifier, the data record enrichment module checks the table for the handset type identifier mapped to the subscriber identifier and adds the corresponding handset type identifier, if it is present in the table, to the handset type identifier field in the data record.

Abstract: A controller for reducing a transient variation of gain of an optical amplifier is disclosed. The controller includes a control circuit adapted to generate an electrical signal mimicking optical gain transient variation upon an abrupt change in input loading conditions. The electrical signal is applied to a variable optical attenuator disposed downstream of the active optical fiber of the optical amplifier. The control circuit can be realized in a variety of ways, but preferably it includes a logarithmic amplifier and a high-pass filter sequentially connected. The logarithmic amplifier is connected to an input tap/photodetector, and the high-pass filter is connected to the variable optical attenuator.