Abstract: A touchless access control system is configured to provide configurable selective access to an area to users in possession of a smartphone or other user device. On-site components of the system are configured to operate entirely offline, and utilize the capabilities of the user device to perform any required communications over the internet. The system also operates without any required pre-configuration of the user device, so users are able to utilize the system without first installing proprietary software or creating user accounts. The system may also be configured by a facility administrator to allow varying levels of selective access filtering based on determinable characteristics of the user device. The system also generates valuable data describing the flow through and use of facilities to which access is controlled.

Abstract: An optical transmission apparatus of an embodiment is an apparatus for redundantly transmitting a multiplexed signal obtained by multiplexing N (N is an integer of 2 or greater) optical signals having different wavelengths, the apparatus including: a first demultiplexing unit to which a first multiplexed signal is input, the first demultiplexing unit configured to demultiplex the input first multiplexed signal into the N optical signals; N first detection units to which the N optical signals demultiplexed by the first demultiplexing unit are respectively input, each of the N first detection units configured to detect presence or absence of deterioration of a corresponding input optical signals of the input optical signals based on a signal level of the corresponding input optical signal; a second demultiplexing unit to which a second multiplexed signal is input, the second demultiplexing unit configured to demultiplex the input second multiplexed signal into the N optical signals; N second detection units to

Abstract: Methods and apparatuses for testing a photonic integrated circuit and a corresponding sample holder and a photonic integrated circuit are provided. Here, a location for an illumination light beam can be selected by way of a scanning device, with the result that targeted coupling of the illumination light into the photonic integrated circuit is made possible.

Abstract: A test apparatus has at least one optical source, a high-speed photodetector, a microcontroller or processor, and electrical circuitry to power and drive the optical source, high-speed photodetector, and microcontroller or processor. The apparatus measures the frequency response and optical path length of a multimode optical fiber under test, utilizes a reference VCSEL spatial spectral launch condition and modal-chromatic dispersion interaction data to estimate the channels total modal-chromatic bandwidth of the fiber under test, and computes and presents the estimated maximum data rate the fiber under test can support.

Abstract: In some examples, fiber optic link intermittent fault detection and localization may include determining, for a fiber optic link that is to be analyzed, at least one section corresponding to the fiber optic link, at least one detection threshold corresponding to the at least one section, and a reference trace for the fiber optic link. A real-time trace may be acquired for the fiber optic link, and a comparison trace may be generated based on analysis of the reference trace and the real-time trace. Based on analysis of the at least one section to determine whether at least one section level parameter determined from the comparison trace exceeds the at least one detection threshold, an event associated with the fiber optic link may be identified.

Abstract: The present disclosure has an object to provide a technique for enabling a communication state to be confirmed not in a communication building but in a work site, and to provide a technique for enabling correct splicing between optical cables to be confirmed before fusion splicing.

Abstract: The present disclosure relates to an optical time domain reflectometry method including the steps of feeding a plurality of unipolar optical probe signals to a near end of an optical path under test, receiving a corresponding plurality of reflected unipolar optical receive signals, creating a corresponding plurality of digital receive data signals, calculating at least one correlation signal by correlating the digital receive data signals with a bit sequence corresponding to a respective probe bit sequence, and determining the signal propagation delay between the near end of the optical path and a respective reflective position. The present disclosure also relates to an optical time domain reflectometry system in which this method is implemented and a computer program having instructions to cause the optical time domain reflectometer and to execute the method herein.

Abstract: Systems, devices, and techniques relating to optical communications are described. A described hub optical module includes an optical transceiver configured to communicate with edge optical modules of respective edge devices via an optical communication network, the edge optical modules comprising edge interfaces; and a controller coupled with the optical transceiver. The controller can be configured to provide, to a hub device, hub interfaces which are configurable to respectively correspond to different optical subcarriers transmitted from and received by the optical transceiver. The controller can advertise, to the hub device, an application select code to enable the hub device to configure an operational mode and to selectively enable each of the hub interfaces in the operational mode, store one or more associations among the hub interfaces and the edge interfaces, and configure one or more cross-connections among the hub interfaces and the optical subcarriers based on the one or more associations.

Abstract: In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

Abstract: In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

Abstract: In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

Abstract: An optical waveguide device includes: a substrate having an electro-optic effect, an optical waveguide formed on the substrate, a light-receiving element disposed on the substrate and monitoring a light wave propagating through the optical waveguide or a light wave that is radiated from the optical waveguide; and a monitoring optical waveguide extending from the optical waveguide to the light-receiving element, in which the monitoring optical waveguide has a U-turn waveguide with respect to an output direction of the optical waveguide, and the light-receiving element is disposed at a part of the monitoring optical waveguide after the U-turn waveguide.

Abstract: Devices, computer-readable media and methods are disclosed for selecting paths in reconfigurable optical add/drop multiplexer (ROADM) networks using machine learning. In one example, a method includes defining a feature set for a proposed path through a wavelength division multiplexing network, wherein the proposed path traverses at least one link in the network, and wherein the at least one link connects a pair of reconfigurable optical add/drop multiplexers, predicting an optical performance of the proposed path, wherein the predicting employs a machine learning model that takes the feature set as an input and outputs a metric that quantifies predicted optical performance, and determining whether to deploy a new wavelength on the proposed path based on the predicted optical performance of the proposed path.

Abstract: A computer implemented method of routing service requests to service instances in a service mesh. The method comprises monitoring one or more performance characteristics of each of a plurality of network links to service instances. The method further comprises making a prediction of the network latency of transmitting a service request via each of at least two of the plurality of network links and selecting one of the plurality of service instances and routing the service request thereto based on the predictions of the network latencies.

Abstract: A system and method for efficient optical signal amplification with system monitoring features are provided. For example, an optical repeater may include two different 4-port thin-film gain flattening filters (TF-GFFs), which may be connected to provide a high-loss loop-back (HLLB) path in the optical repeater for system monitoring. The 4-port TF-GFF may have four different ports and may integrate the functionalities of a conventional GFF and a coupler into a single component, thereby increasing power efficiency of the optical repeater.

Abstract: In some examples, fiber optic link intermittent fault detection and localization may include determining, for a fiber optic link that is to be analyzed, at least one section corresponding to the fiber optic link, at least one detection threshold corresponding to the at least one section, and a reference trace for the fiber optic link. A real-time trace may be acquired for the fiber optic link, and a comparison trace may be generated based on analysis of the reference trace and the real-time trace. Based on analysis of the at least one section to determine whether at least one comparison trace section level indicator determined from the comparison trace exceeds the at least one detection threshold, an event associated with the fiber optic link may be identified.

Abstract: The present disclosure is directed to systems and methods for calculating a modal time delay and a modal bandwidth. For example, a method may include: transmitting an intensity-modulated light through a mode conditioner to generate a mode-conditioned intensity-modulated light; transmitting the mode-conditioned intensity-modulated light through an optical fiber under test (FUT) to excite a plurality of modes of the optical FUT; converting the mode-conditioned intensity-modulated light transmitted through the optical FUT into an electrical signal; measuring, based on the electrical signal, a transfer function or a complex transfer function of the optical FUT based on at least on one pair of the plurality of modes; calculating a modal delay time of the optical FUT based on the transfer function or the complex transfer function; and calculating a modal bandwidth of the optical FUT based on the modal delay time, the modal bandwidth being calculated for any given launch conditions of the plurality of modes.

Abstract: Aspects of the subject disclosure may include, for example, a device in which a processing system enables mobile devices on a communication network to perform latency tests to obtain first latency test data, determines an edge latency for each mobile device resulting in edge latencies, identifies a group of mobile device clusters according to the edge latencies, and identifies network edge server locations according to the group of mobile device clusters. The processing system also receives second latency test data from each of the network edge servers, and determines a data center latency for each of the network edge servers, resulting in a plurality of data center latencies. The processing system also identifies a data center location according to the data center latencies, and determines a network topology for the communication network; the network topology includes the data center location and the edge server locations. Other embodiments are disclosed.

Abstract: In one embodiment, a distributed antenna system comprises: at least one master unit; at least one remote antenna unit communicatively coupled via a switch to the master unit by a primary cable and a secondary cable both coupled to the switch, the remote antenna unit comprising a compensating link check module that outputs a control signal to the switch, wherein the switch selects between the primary and secondary cable in response to the control signal; wherein the compensating link check module controls the switch to momentarily select the secondary cable to perform a link check during which the remote unit measures a quality metric of a downlink signal received via the secondary cable; and upon initiation of the link check, the compensating link check module adjusts an attenuation of the downlink signal received on the secondary cable by loading calibration settings for the secondary cable into a compensation attenuator.

Abstract: Embodiments of this disclosure provide an apparatus and method for monitoring an optical signal to noise ratio, a receiver and a communication system. The apparatus for monitoring an optical signal to noise ratio includes extracting signals from signals obtained after an equalization processing is performed on optical signals received by a receiver, the optical signals including signals of known frequencies, and the signals extracted having the same spectral characteristics as the signals of known frequencies; correcting, according to filtering parameters used in the equalization processing, the signals extracted and outputting corrected signals; and calculating an optical signal to noise ratio according to the corrected signals. According to the embodiments of this disclosure, the optical signal to noise ratio may be calculated more accurately.

Abstract: A frequency difference compensation unit (510) generates a carrier recovery signal by compensating for a frequency difference between a local light beam and an optical signal in a plurality of digital signals. A first symbol determination unit (521) determines the symbol position of the carrier recovery signal in which a frequency difference is compensated for, in accordance with the signal arrangement of multi-value modulation. A second symbol determination unit (522) determines the symbol position of the carrier recovery signal in which a frequency difference is compensated for, in accordance with a signal arrangement in which the number of multi-values of the multi-value modulation is reduced.

Abstract: An interface mapping method includes obtaining, at a network controller, device information of network devices configured to be in communication with each other through an optical network. The network devices include a plurality of colored interfaces that support a range of wavelengths for communication in the optical network. Interface information of the colored interfaces of the network devices is obtained, and optical power information associated with each of the colored interfaces is obtained. Optical power margins for a transmitter interface of the colored interfaces. The transmitter interface is controlled to transmit a power sequence based on the optical power margins, and power readings are obtained from a receiver interface of the colored interfaces. A topology between the colored interfaces is discovered based on the power sequence and the power readings.

Abstract: A light physical constant measurement method includes: virtually dividing an optical transmission medium along a propagation direction to set a plurality of first segments; and estimating light physical constants of the plurality of first segments based on the result of a first propagation simulation that uses a model in which an input optical signal of each of the plurality of intensities propagates sequentially through the plurality of first segments, and in the estimating of light physical constants of the plurality of first segments, the light physical constants of the plurality of first segments are searched for using an evaluation function of evaluating a difference between a measured power spectrum of an output optical signal and a power spectrum of the output optical signal obtained as a result of the first propagation simulation, to estimate the light physical constants of the plurality of first segments.

Abstract: A self-contained calibration method for improving stability of an optical source in an optical network test instrument includes performing a temperature sweep test of the optical source. Optical output power of the optical source is periodically measured. A temperature correcting value is generated based on the measured optical output power. The optical output power of the optical source is adjusted by applying the temperature correcting value to obtain a substantially constant optical output power of the optical source.

Abstract: Systems, devices and techniques for processing an optical signal transmitted from a source over a transmission medium having a length L and performing compensation of non-linear distortions include formulating the compensation as a digital back propagation algorithm by logically dividing the length L into N steps and compensating non-linear distortions for each step as a function of an attenuation adjusting constant parameter that can be selected from a range between 0.3 and 0.7.

Abstract: A method and system for generating an optical channel signal for transmission through an optical fiber link of an optical communications system. A digital filter processes an input data signal using a compensation function and a shaping function to generate a pair of multi-bit sample streams representing a target optical E-field envelope of the optical channel signal. A modulator modulates an optical carrier light using the pair of multi-bit sample streams to generate the optical channel signal. The compensation function is designed to at least partially compensate impairments of the optical fiber link. The predetermined shaping function is designed to modify a baseband spectrum of the target optical E-field envelope.

Abstract: Disclosed are methods and devices for distributed sensing of a measurable parameter employing stimulated Brillouin scattering in an optical fiber. A frequency-modulated or phase-modulated light wave is transmitted into the optical fiber. A scattered light wave in the optical fiber is monitored for sensing a measurable parameter. In some embodiments, the calculating step may include calculating a distance of a sensed location along the optical fiber using the monitored time of arrival.

Abstract: Techniques for avoiding dynamic domain name system (DNS) collisions are disclosed. In one particular exemplary embodiment, the techniques may be realized as a method for avoiding dynamic domain name system (DNS) collisions comprising: storing a first location associated with a first client device, a second location associated with a second client device, and a third location associated with a network, receiving, from the first client device, a first notification indicating an Internet Protocol (IP) address via the network, receiving, from the second client device, a second notification indicating the IP address via the network, determining a most likely owner of the network between the first client device and the second client device based on the first location, the second location, and the third location, and applying a content filtering policy associated with the first client device when the first client device is determined to be the most likely owner.

Abstract: A system for performing in-band reflection analysis in a passive optical network. The system comprises an optical line terminal (OLT) that includes a transceiver for transmitting continuous downstream data modulated on a first wavelength and receiving upstream burst data modulated on a second wavelength, the OLT further includes a receiver for receiving signals reflected from the PON that are modulated on the first wavelength, wherein the continuous downstream data comprises user data and a test data pattern; and a reflection analysis unit for cross-correlating between a time-shifted version of the transmitted test data pattern and the reflected signals, wherein the test data pattern is time-shifted relatively for an optical location to be tested.

Abstract: The length of the optical fiber section under tension expands by a certain amount that is proportional to the level of tension applied to it. Monitoring the variations in the phase of the arriving signal allows to discover a fiber that is subject to a certain level of mechanical tension. With the method and apparatus according to the present invention it is possible to protect optical communication channels against failures in an optical transmission fiber that are caused by any kind of mechanical disturbances.

Abstract: A method includes sweeping an optical frequency of an optical signal by an optical transmitter controlling an electric-field information signal corresponding to a transmitted signal, providing different polarization states for individual frequencies of the optical signal by the optical transmitter controlling a mixture of a first electric-field information signal corresponding to a first transmitted signal and a second electric-field information signal corresponding to a second transmitted signal, obtaining, for individual frequencies of the optical signal, polarization dependent characteristics corresponding to different frequencies, when the optical transmitter sweeps the frequency of the optical signal, by an optical receiver calculating a polarization-dependent characteristic of an optical transmission line between the optical transmitter and the optical receiver, based on items of received-electric-field information corresponding to the different polarization states, and obtaining statistical information

Abstract: An exemplary method is provided for determining a maximum transmission distance for an optical link that has heterogeneous types of optical fiber segments. The method includes retrieving from a database a maximum transmission reach value for each type of optical fiber present in the optical link. A length of each type of the optical fiber to reach a distance is computed, where, for each type of the optical fiber present in the optical link, segments are summed from a starting point to the distance to determine the length of each type of the optical fiber along the optical link. The length for each type of the optical fiber in the optical link is normalized by multiplying the length of each type of the optical fiber by a weight chosen as a function of the maximum transmission reach value for each type of said optical fiber.

Abstract: An optical transmission system for optically transmitting information between apparatuses via an optical transmission path. The system includes: a sending unit that emits, to the optical transmission path, excitation light for detecting an inter-apparatus connection via the path; a responding unit that receives the excitation light from the path and emits detection light to the path using light energy of the excitation light; a response receiving unit that receives the detection light from the path and outputs a detection light current; a detecting unit that detects presence/absence of the inter-apparatus connection based on the detection light current; a light signal transmitting unit that emits, to the path, a light signal for optically transmitting the information based on the detection result by the detecting unit; and a light signal receiving unit that receives the light signal from the path.

Abstract: For testing an optical network, a transmission module transmits a first optical power level on a first optical port of an optical assembly. The optical assembly includes the first optical port, one or more of an optical cable and an optical waveguide, and a second optical port. The optical assembly is installed in an assembled computer in a state suitable for an end user. A measurement module measures a second optical power level on the second optical port, and a determination module determines a quality level by determining if the second optical power level is below a quality threshold value. The transmission module, the measurement module, and the determination module function within an assembled computer in a state suitable for an end user.

Abstract: A method for testing the operation of an optical fiber cable in a communication network using an optical loss test set (OLTS) instrument includes receiving a range of identifiers of fibers to be tested. Identifiers of a first fiber set to be tested are displayed. The first fiber set comprises one or more fibers. The first fiber pair is included in the range. The first fiber pair is a next fiber pair to be tested. A determination is made whether the first fiber set is connected to the OLTS instrument. In response to determining that the first fiber set is connected to the OLTS instrument, a test of the first fiber set operation is performed using the OLTS instrument. Identifiers of a second fiber set are displayed. The second fiber set is included in the range and constitutes a next fiber set to be tested.

Abstract: An optical transmitter configured to mitigate the adverse effects of fiber nonlinearity by altering the transmitted constellation symbols based on specific nonlinear characteristics of a fiber-optic link over which the optical transmitter is configured to transmit and on an a priori estimate of the nonlinear component of the optical-signal distortion in that fiber-optic link. In an example embodiment, each constellation symbol is altered by a respective perturbation amount determined using (i) a calculated or measured nonlinear transfer function corresponding to the fiber-optic link and (ii) a set of neighboring constellation symbols that are expected to contribute to the nonlinear distortion of the optical signal carrying the present constellation symbol due to the fiber nonlinearity. In various embodiments, different appropriate perturbation amounts can be selected to approximately pre-compensate nonlinear distortions caused by various nonlinear optical effects, such as four-wave mixing, etc.

Abstract: A method is provided for detecting movement indicative of intrusion events on optical drop fibers of a network where the individual drop fiber can be identified to locate the event. The method uses a monitor system at the network end and multiplexing the monitor signal along the individual fibers to the respective terminals. At each of the terminals, the monitor signal is returned unchanged or in modified form along the same or different fibers to the network end. At the network end the received monitor signals is analyzed for changes in said monitor signals indicative of movement. Which one or more of the drop fibers has triggered the alarm is determined by modifying the monitor signal in wavelength or polarization, or by applying a modulation at the source and/or at multiplexing and/or at returning so that the monitor signal of one drop fiber has a difference from the monitor signal of another drop fiber.

Abstract: A universal optical receiver may include an optical channel monitor configured to acquire spectral data for an optical signal on at least one selected optical channel, a tunable local oscillator configured to be tuned to a center frequency of the optical signal on the at least one selected optical channel, a storage device configured to store data associated with the optical signal responsive to acquisition of the spectral data and tuning of the tunable local oscillator, and processing circuitry configured to execute an algorithm that employs a plurality of binary distinctions based on physical characteristics of the optical signal and employs at least one calculation of figure of merit associated with a series of parameter values of the optical signal to identify a format of the optical signal.

Abstract: A remote node, e.g., a client-side node or a service-side node, writes wavelength information into an overhead message of a packet carried by an optical signal when an optical port associated with the remote node is deployed. The overhead message explicitly identifies the wavelength channel associated with the newly deployed optical port to a hub node in a WDM optical network. The hub node identifies the new wavelength channel associated with the newly deployed optical port based on the overhead message to enable the hub node to associate the new wavelength channel with the newly deployed optical port.

Abstract: Systems and methods of aligning an optical interface assembly with an integrated circuit (IC) are disclosed. The method includes emitting light from an optical transmitter, passing the emitted light through the optical interface assembly in a first direction, and reflecting the emitted light from a reflective surface disposed immediately adjacent a front end of the optical interface assembly to define reflected light that travels back through the optical interface assembly in a second direction that is substantially opposite the first direction. The reflected light is received by an optical receiver that generates in response a receiver signal. The relative position of the optical interface assembly and the IC is adjusted to achieve an aligned position based on the receiver signal. The disclosure is also directed to a test plug for aligning an optical interface assembly to the IC.

Abstract: According to one embodiment of a system for measuring differential mode delay couples with a pulse generator to generate an input electrical pulse, a photo detector to receive optical pulse from an optical fiber, and a digital oscilloscope to receive an output electrical pulse transmitted from the photo detector, the system includes: a laser diode, a first lens and a second lens, a pigtail, and a spliced optical connector, wherein the laser diode receives the input electrical pulse to produce a laser beam, the first lens and the second lens focus the laser beam into the pigtail, the spliced optical connector connects the pigtail and the input end face of the optical fiber such that the optical pulse from the output end face of the optical fiber is received by the photo detector.

Abstract: The present invention relates to an apparatus and a method for fiber optic perturbation sensing, in which it is possible to easily confirm whether an intrusion is occurred, an intrusion position, and an intrusion object by dividing an optical signal output from the optical signal generation unit, progressing the divided optical signals to optical paths having different lengths, coupling the divided optical signals to generate an sensing optical signal, outputting the generated sensing optical signal to the sensing optical fiber, dividing the sensing optical signal returning from the sensing optical fiber, progressing the divided sensing optical signals to the optical paths having different lengths, and coupling the divided sensing optical signals to generate an interference sensing optical signal.

Abstract: A method for determining an optical signal-to-noise ratio penalty as a measure for a quality of an optical signal transmitted via an optical link between a source optical node and a destination optical node in an optical network, the method includes collecting information of the optical link; determining a configuration parameter Pconf of the optical link based on the information of the optical link; adjusting the configuration parameter Pconf to an adjusted configuration parameter P?conf according to linear impairments in the optical link; and determining the optical signal-to-noise ratio penalty based on a non-linear function of the adjusted configuration parameter P?conf, the non-linear function accounting for non-linear impairments in the optical link.

Abstract: There is provided a method of determining transmission quality of a path in an optical communication network system obtained by connecting a plurality of networks, the method including: acquiring a value representing transmission performance corresponding to a network condition of each of spans in the path in the optical communication network system; and determining the transmission quality of the path on the basis of the acquired value representing transmission performance corresponding to the network condition of each of spans.

Abstract: Provided is a waveform reconstruction device capable of easily reconstructing an accurate time waveform of an optical signal without using an ultrafast time gate or a reference light source.

Abstract: A system and method is disclosed that allows for the monitoring, analyzing and reporting on performance, availability and quality of optical network paths. The correlation of PM parameter metrics to client connections, coupled with threshold-based alarm generation provides a proactive and predictive management, reporting and analyzing of the health and effectiveness of individual path connections to alert Operational Support (OS) staff and/or customers to signal degradation and impending Network Element (NE) failures. The system and method performs in real-time processing intervals required for alarm surveillance in a telecommunications network.

Abstract: A border node of an optical network receives optical channel traffic parameter(s) associated with an optical channel from an optical channel originator external to the optical network. The received parameters are used to determine the suitability of at least one optical path within the optical network for an externally originating optical channel. If a suitable optical path is determined, an optical channel availability message indicating the availability at the border node of an optical path within the optical network for the optical channel is sent to the optical channel originator. The optical channel originator determines an available optical channel status of the optical channel from the received optical channel availability message for the optical channel.

Abstract: A remotely controlled fiber testing method has the steps of: building a fiber network system including a local fiber station and a remote fiber station; sending a modulated signal to the remote fiber station by the local fiber station; demodulating the modulated signal to obtain a control command by the remote fiber station; executing the control command to obtain a testing result by the remote fiber station; modulating the testing result and sending the testing result back to the local fiber station; and demodulating the testing result by the local fiber station. Only one technician appointed to the local fiber station is sufficient to do the testing action. Therefore, the personnel cost is effectively reduced.

Abstract: An optical device includes an optical waveguide that includes an incident waveguide, parallel waveguides along an electrode, and emission waveguides, formed on a substrate having an electro-optical effect, a first emission waveguide among the emission waveguides is set as an output waveguide of signal light, for output to an external destination and a second emission waveguide among the emission waveguides is set as a monitoring optical waveguide for the signal light; a photodetector that is disposed over the monitoring optical waveguide; and a groove formed on a portion of the substrate, where the photodetector of the monitoring optical waveguide is disposed. The monitoring optical waveguide has a width that, as compared with the width at a starting point side, is formed to increase as the monitoring optical waveguide approaches the groove.

Abstract: Various systems and methods for using credits to determine cable length are described herein. A number of available credits is determined at a transmitter, the credits being received at the transmitter from a receiver, and each of the credits being used for the transmitter to transmit a packet to the receiver. An average number of credits for a period is determined. The cable length between the transmitter and the receiver is determined based on the average number of credits for the period.