Abstract: The invention relates to an optical regenerator for a differential phase modulated data signal which comprises, in addition to a unit for bit-by-bit gauge leveling, a unit for the regeneration of the phase of individual symbols of the differential phase modulated data signal. After the bit-by-bit gauge leveling, the data signal that is preset in amplitude is divided into a first and a second data signal. Phase errors of individual signals are detected for the first data signal in a phase error detection unit, are transformed into a correction signal, and are conveyed to a phase error correction unit. The second data signal is corrected in the phase error correction unit, depending on the correction signal conveyed thereto in the phase of said data signal, in such a way that a differential phase modulated data signal, regenerated in amplitude and in phase, is delivered at the output of the correction unit.

Abstract: Systems and methods for operating transponders that automatically accommodate multiple received signal types. The different signal types may include different clients such as, e.g., SONET/SDH, G.709, 10 Gigabit Ethernet, etc. as well as different data rates. A transponder can automatically detect the client signal type and data rate and respond by processing the received signal appropriately, notifying a control processor, and invoking an appropriate performance monitoring method. This maximizes the network operator's flexibility and ease of configuration.

Abstract: In an optical transmission device, when wavelength division multiplexed light formed from signals of a plurality of wavelengths are received, an optical signal of one wavelength comprised in this wavelength division multiplexed light is planarized and non-signal light of the same wavelength is reproduced. The reproduced light is modulated with a transmission data string, an optical signal is generated, and a wavelength division multiplexed light comprising the generated optical signal is transmitted.

Abstract: An economical optical network is constituted by effectively using network resources by using the minimum number of, or minimum capacity of 3R repeaters. 3R section information corresponding to topology information on the optical network to which an optical node device itself belongs is stored, and the 3R section information stored is referred so as to autonomously determine whether or not the optical node device itself is an optical node device for implementing the 3R relay when setting an optical path passing through the optical node device itself. Alternatively, when the optical node device itself is a source node, another optical node device for implementing the 3R relay among the other optical node devices through which the optical path from the optical node device itself to the destination node passes is identified, and this identified optical node device is requested to implement the 3R relay when setting an optical path in which the optical node device itself is a source node.

Abstract: A single sideband signal is generated from an input optical signal. An optical phase modulator performs optical phase modulation on the input optical signal in accordance with a control signal to produce the single sideband signal. A converter converts the input optical signal into a corresponding electrical signal. A control signal generator generates the control signal in response to an optical signal pulse shape of the input optical signal.

Abstract: The path selection and wavelength assignment to a selected path are performed by mapping the wavelength reach to the demand distribution (agile reach) resulting in a 50-60% increase in the network reach. The network reach is further increased (about 2.2 times) when on-line measured performance data are used for path selection and wavelength assignment. The connections may be engineered/upgraded individually, by optimizing the parameters of the entire path or of a regenerator section of the respective path. The upgrades include changing the wavelength, adjusting the parameters of the regenerator section, controlling the launch powers, mapping a certain transmitter and/or receiver to the respective wavelength, selecting the wavelengths on a certain link so as to reduce cross-talk, increasing wavelength spacing, etc.

Abstract: The optical node connects N networks to each other (where N is an integer larger than one). Each of the N networks respectively includes a first transmission path and a second transmission path. The optical node includes a switching unit that connects the first transmission path of one network of the N networks to other (N?1) networks; a failure detector that detects failure in the first transmission path of the network; and a control unit that causes the switching unit to connect the second transmission path of the network to the other (N?1) networks when the failure is detected.

Abstract: This provides an optically transmitting apparatus, an optically transmitting system and an optically transmitting method. This receives an optical signal which is configured in accordance with any one frame format among a plurality of frame formats and includes at least a clock signal and a data signal, and performs an optical-electric/electric-optical conversion on the received optical signal, and extracts the clock signal and the data signal, which correspond to the frame format, from the optical-electric converted signal. This correlates and stores an idle code indicative of a block where the actual data is not communicated and the frame format, reads the idle code from the extracted data signal, identifies the frame format corresponding to the read idle code, and executes a transmitting process in accordance with the identified frame format.

Abstract: A pulse reshaper for reshaping and re-amplifying optical signals in a communications network by adjusting threshold and amplification characteristics of a semiconductor optical amplifier (SOA) having first and second reflective regions optically cooperating at each of an input signal wavelength (?s) and an offset wavelength (?C) proximate the input signal wavelength (?s). In one embodiment, a vertical cavity semiconductor optical amplifier (VCSOA) device, comprising dual mode reflectors optically cooperating at each of an input signal wavelength (?s) and an offset wavelength (?C) proximate the input signal wavelength (?s) to provide thereby non-linear amplification of input signal (?s).

Abstract: An optical network includes an optical ring that is capable of transmitting, between two or more nodes, a plurality of working traffic streams that include traffic transmitted in one of a plurality of wavelengths. A node is capable of transmitting, in a first wavelength, a first protection traffic stream associated with a first working traffic stream, in response to an interruption of the first working traffic stream. A node is also capable of transmitting, in a second wavelength, a second protection traffic stream associated with a second working traffic stream, in response to an interruption of the second working traffic stream. The optical network also includes a regeneration element capable of selectively regenerating the first protection traffic stream. The regeneration element is also capable of tuning the regeneration element to receive traffic in the second wavelength and of selectively regenerating the second protection traffic stream.

Abstract: The present invention is an optical clock signal extraction device, comprising first conversion means and second conversion means for enabling to extract an optical clock signal without depending on the polarization direction of an input optical signal. The first conversion means comprises a first optical converter and a continuous wave light source of which wavelength is ?2, where an input optical signal of which wavelength is ?1 and continuous wave light of which wavelength is ?2 are input to the first optical converter, and an intermediate optical signal of which wavelength is ?2 is generated and output without depending on the polarization direction of the input optical signal. The second conversion means has a second optical converter, where the intermediate optical signal is input to the second optical converter, and an optical clock signal of which wavelength is ?3 is generated and output by the passive mode locking operation of the second optical converter.

Abstract: Methods and apparatus for providing amplification to coarse wave division multiplexing channels or signals are disclosed. According to one aspect of the present invention, an arrangement that adds gain to a set of signals that may be divided into a first band including signals of lower wavelengths and a second band including signals of higher wavelengths includes a multiplexer, first and second optical amplifiers, and a processing arrangement. The multiplexer multiplexes the set of signals. The first optical amplifier has a first gain peak and provides amplification to the set of signals, while the second optical amplifier has a second gain peak and provides amplification to the second band but not to the first band. The processing arrangement passes the second band from the first optical amplifier to the second optical amplifier, and substantially prevents the first band from passing from the first optical amplifier to the second optical amplifier.

Abstract: Various embodiments of the present invention are directed to compact systems for generating polarization-entangled photons. In one embodiment of the present invention, a non-degenerate, polarization-entangled photon source comprises a half-wave plate that outputs both a first pump beam and a second pump beam, and a first beam displacer that directs the first pump beam into a first transmission channel and the second pump beam into a second transmission channel. A down-conversion device converts the first pump beam into first signal and idler photons and converts the second pump beam into second signal and idler photons. A second beam displacer directs both the first signal and idler photons and the second signal and idler photons into a single transmission channel. A dichroic mirror directs the first and second signal photons to a first fiber optic coupler and the first and second idler photons to a second fiber optic coupler.

Abstract: An economical optical network is constituted by effectively using network resources by using the minimum number of, or minimum capacity of 3R repeaters. 3R section information corresponding to topology information on the optical network to which an optical node device itself belongs is stored, and the 3R section information stored is referred so as to autonomously determine whether or not the optical node device itself is an optical node device for implementing the 3R relay when setting an optical path passing through the optical node device itself. Alternatively, when the optical node device itself is a source node, another optical node device for implementing the 3R relay among the other optical node devices through which the optical path from the optical node device itself to the destination node passes is identified, and this identified optical node device is requested to implement the 3R relay when setting an optical path in which the optical node device itself is a source node.

Abstract: A wavelength division multiplexed optical signal transmission method, a wavelength division multiplexed optical signal transmission system and an optical repeater enabling the number of wavelengths to be detected without error even when optical noise is caused in the optical repeater and such functions as adjustment and monitoring of the level of a wavelength division multiplexed optical signal to be performed properly. An optical repeater processes controlled optical signals of different wavelengths individually based on a control optical signal that contains wavelength number information indicating the total number of wavelengths and the presence or absence of a controlled optical signal with respect to each wavelength. Thus, even when optical noise is caused in the optical repeater, the number of wavelengths can be detected without error and such functions as adjustment and monitoring of the level of a wavelength division multiplexed optical signal can be performed properly.

Abstract: A technique for improving optical cross-connections comprises placing a switch in front of a number of processing units. So configured, the units are no longer dedicated to a specific link or signal. When necessary, a unit is connected/disconnected to one or more optical links by the switch to carry out any number of processing functions, such as regeneration, Raman pumping, dispersion equalization/compensation or performance monitoring. Because the units are no longer dedicated to specific links the cost of the cross-connections and the network it is a part of can be reduced.

Abstract: A passive optical network is provided, which includes an optical central office connected to a line termination device by a branch of the network including a passive amplification medium. The central office is adapted to send/receive a first data optical signal and has a first amplifier for sending a second amplification optical signal. The second signal exciting the amplification medium to amplify the optical power of an optical signal. The line termination device is adapted to receive the first optical signal, modulate the second amplification optical signal; and inject the modulated second signal into the network.

Abstract: Systems and methods for repeating optical signals. A scalable transceiver based repeater includes one or more transceivers. Each transceiver includes an optical receiver that receives a channel of an optical signal. The optical transmitter in each transceiver transmits the channel received by the associated optical receiver. A switch is used to redirect the channels, which may be in an electrical form at the switch, from the optical receivers back to the optical transmitters. The switch can also be used to add/drop the channels from the repeater. The optical transmitter and/or the optical receiver of each transceiver may also include a clock/data recovery circuit (CDR). The repeater is scalable because transceivers can be added/replaced as needed. A demultiplexor can separate an optical signal into the channels that are received by the optical receivers. A multiplexor combines the channels generated by the optical transmitters.

Abstract: A method of dynamically adjusting an optical module in an optical system including a plurality of transmission channels includes the following steps: measuring the quality of the optical signal at the output of the system as defined by an error function, varying an optical parameter of at least one module of the system, measuring a differential error introduced by each variation on the error function of the optical signal at the output of the system, estimating an operating point of the system corresponding to an expected reduction of the error function, and adjusting a parameter of an optical module toward the operating point of the system.

Abstract: A RF-synchronization system includes a laser that creates pulse trains for synchronization. A modulation means transfers the timing information of the pulse train into an amplitude modulation of an optical or electronic system. A synchronization module changes the driving frequency of the modulation means until it reaches a phase-locked state with the pulse train.

Abstract: There is provided an optical regenerative amplifier for regenerative amplification of a binary phase shift-keying (BPSK) sequence of optical signals having a predetermined time slot between any adjacent signals.

Abstract: This device for optically regenerating pulses includes a synchronous intensity modulator to provide time synchronization for pulses passing through it and to stabilize intensity fluctuations in the pulses. In addition, it includes noise suppression circuitry in the form of a saturable absorber that is distinct from the synchronous intensity modulator and the intensity fluctuations stabilizer.

Abstract: A device for processing of an optical input signal includes at least a first data signal. A first optical resonator provides a reference signal by optical filtering of the optical input signal. The first optical resonator is matched with a predetermined reference wavelength of the first data signal. A second optical resonator provides a sideband signal by optical filtering of the optical input signal. The second optical resonator is non-matched with the predetermined reference wavelength of the first data signal. An optical combiner combines the sideband signal with the reference signal to form an optical output signal.

Abstract: A method and apparatus for controlling a plurality of infrared devices (ICDs) is provided herein. A remote controller is used to generate an optical signal for controlling a plurality of ICDs. The optical signal generated by the remote controller is converted into an electrical signal by an infrared repeater device. An implementation of such a system includes a rotary mechanical switch to direct the electrical signal generated by the infrared repeater device to a light emitting diode (LED) located near one of the plurality of ICDs. The LED converts the electrical signal into an optical signal and re-transmits the optical signal to the one of the plurality of ICDs. The system allows controlling the plurality of ICDs located in a remote location without having the user commute closer to such ICDs.

Abstract: An optical repeater which includes a wavelength converter and a bit rate converter. The wavelength converter converts a wavelength of an optical signal from a first optical network to a wavelength of a second optical network. The bit rate converter converts a bit rate of the optical signal from the first optical network to a bit rate of the second optical network. The optical repeater transmits the optical signal from the first optical network to the second optical network at the converted bit rate and wavelength.

Abstract: A quantum repeater includes a transmitter portion including a source, a set of matter systems, and an optical system. The source produces a probe pulse in a probe state having components with different photon numbers, and each matter system has at least one state that interacts with photons in the probe pulse to introduce a change in a phase space location of the probe state. The optical system can direct the probe pulse for interaction with one of the matter systems and direct light from the matter system for transmission on a first channel.

Abstract: An optical signal regenerative repeater is provided including at least one first optical 3R repeater based on an optical communication signal pulse, regenerating the optical communication signal pulse. The first optical 3R repeater comprises a first clock extraction unit extracting a clock from the optical communication signal pulse and generating a first optical clock pulse synchronized with the extracted clock. The first optical 3R repeater also comprises a first optical gate, which is opened and closed in accordance with a control light corresponding to the optical communication signal pulse, which receives as a controlled light the first optical clock pulse generated by the first clock extraction unit, and which generates a first regenerated signal pulse corresponding to said optical communication signal pulse. Further, a pulse time width of the control light and the controlled light is different.

Abstract: An all-optical processor and method for simultaneous 2R regeneration of the multiple wavelength-division-multiplexed (WDM) channels comprising: a nonlinear medium, wherein the nonlinear medium comprises one or more highly-nonlinear fiber (HNLF) sections adapted to receive multiple WDM channels from the input, and wherein further the HNLF sections are separated by one or more periodic-group delay devices (PGDDs). The all-optical processor may also include one or more amplifiers adapted to receive the multiple WDM channels; one or more de-interleavers adapted to separate the WDM channels into one or more sets of WDM channels, one or more optical band-pass filters to filter the channels received from the amplifier; one or more optical band-pass filters to filter the channels received from the non-linear medium; and one or more interleavers to receive the filtered channels from the periodic band-pass filter and to combine the sets of WDM channels into an output.

Abstract: All-optical system for generating high rate modulated signals. An optical rate increasing device for use with the system includes: an optical loop including an optical amplifier and a gate and having a first terminal and a second terminal coupled to said optical loop, wherein the optical loop is arranged to receive a first periodic signal from the first terminal and to produce therefrom a second periodic signal at the second terminal, and wherein the rate of the second periodic signal is higher than the rate of the first periodic signal.

Abstract: The 3R regeneration system for a retiming, reshaping, and reamplifying an optical signal includes: first and second input ports in which a connected optical signal is input; an interferometer including first and second branches formed on a substrate, split at a common input node, combined at a common output node, semiconductor optical amplifiers in each of the first and second branches, the first branch being connected to the first input port, and the common input node being connected to the second input port; a self-pulsating laser diode monolithically integrated with the interferometer between one of the first input port and the first branch, and the second input port and the common input node on the substrate, receiving an optical signal, and outputting the optical signal regenerated by optical injection locking; and an output port connected to the common output node.

Abstract: The invention relates to clock recovery in optical communication systems. Optical clock frequencies are recovered from a plurality of optical channels by using a single optical resonator. The optical resonator is matched with the carrier frequencies and the sideband frequencies of the data signals sent at different channels. The separation range of the optical resonator is selected such that the clock frequency of at least one data signal is substantially equal to the separation range of the optical resonator multiplied by an integer greater than or equal to two. The method according to the invention allows the use of different clock frequencies at different optical channels. Furthermore, the method provides considerable freedom to select the spectral positions of the optical channels.

Abstract: The disclosed technology provides a dynamic interconnection system which allows to couple a pair of optical beams carrying modulation information. In accordance with the disclosed technology, two optical beams emanate from transceivers at two different locations. Each beam may not see the other beam point of origin (non-line-of-sight link), but both beams can see a third platform that contains the system of the disclosed technology. Each beam incident on the interconnection system is directed into the reverse direction of the other, so that each transceiver will detect the beam which emanated from the other transceiver. The system dynamically compensates for propagation distortions preferably using closed-loop optical devices, while preserving the information encoded on each beam.

Abstract: An optical repeater which includes a wavelength converter and a bit rate converter. The wavelength converter converts a wavelength of an optical signal from a first optical network to a wavelength of a second optical network. The bit rate converter converts a bit rate of the optical signal from the first optical network to a bit rate of the second optical network. The optical repeater transmits the optical signal from the first optical network to the second optical network at the converted bit rate and wavelength.

Abstract: Span information (information about conditions of a path between a node of interest and another, adjacent node connected thereto) retained in respective nodes is cumulatively transmitted from a add-drop node, which is to become a starting-point node of a certain wavelength path, toward a add-drop node, which is to become an end-point node of the wavelength path. The end-point node autonomously determines a path satisfying predetermined transmission conditions as an optimal pathway of said wavelength path, on the basis of cumulative span information transmitted over the respective plural pathways from the starting-point node to the node of interest. As a result, a load imposed on line design to be performed by a client can be mitigated, and an optimization design for each path (wavelength) matching a mesh-type optical network can be performed.

Abstract: A system includes a pulse reshaper for reshaping and re-amplifying optical signals in a communications network. In one embodiment, a vertical cavity semiconductor optical amplifier (VCSOA) device, comprising dual mode reflectors optically cooperating at each of an input signal wavelength (?s) and an offset wavelength (?c) proximate the input signal wavelength (?s) to provide thereby non-linear amplification of input signal (?s).

Abstract: An optical signal and pump light are input to a nonlinear optical medium. In the nonlinear optical medium, the optical signal is amplified with a nonlinear effect caused by the pump light. A monitor circuit monitors parametric gain in the nonlinear optical medium. A first power controller increases input power of the optical signal so that the gain reaches saturation. A second power controller controls input power of the pump light so as to obtain a desired gain.

Abstract: An optical communication device enabling confirmation of frames flowing through a communication line without affecting such line. The optical communication device includes a first conversion unit that converts a first optical signal transmitting a first frame group including a first maintenance frame into a first electrical signal; a frame duplication unit that receives the first electrical signal, generates a second electrical signal that transmits the first frame group, and outputs the first electrical signal; a second conversion unit that converts the first electrical signal output by the frame duplication unit into a second optical signal; and a third conversion unit that converts the second electrical signal generated by the frame duplication unit into a third optical signal.

Abstract: An optical transmission system includes an optical nonlinear element having nonlinear input/output characteristics, a power detector detecting a power of a specific frequency component related to an optical signal reproduced by the optical nonlinear element, and a variable amplifier amplifying or attenuating the optical signal inputted to the optical nonlinear element. Evaluation of an output waveform is performed based on the power of the specific frequency component detected by the power detector, and a gain of the variable amplifier is properly controlled, so that an input power of the optical signal inputted to the optical nonlinear element can be easily set such that a good output waveform can be obtained without directly measuring the inputted or outputted optical signal.

Abstract: An electrical signal regenerator including an equalizer and a clock data recovery circuit is provided. The clock data recovery circuit is selected when an input signal of a higher bitrate multiplex level is detected, but the clock data recovery circuit is bypassed when an input signal of a lower bitrate multiplex signal is detected. The electrical signal regenerator can be used in an optical switch processing signals of the new OTN according to ITU-T G.709, in which optical signals undergo optical to electrical conversion and are fed to an electrical space switching matrix including a plurality of the switch modules electrically interconnected by means of internal electrical signal paths such as a backplane or electrical cables. The electrical signal regenerator can be coupled to each input of a switching module to check internal cabling of the switching matrix.

Abstract: A method for transmitting traffic in an optical communication system comprising separating the input traffic into a plurality of data signals, parameter encoding the data signals, transmitting each of the data signals on a separate optical channel, receiving the data signals on the channels, parameter decoding the data signals, and combining the plurality of data signals from the channels into output traffic corresponding to the input traffic.

Abstract: In each of a plurality of submarine observation apparatus (1 to n), a branching unit (63) branches fixed-wavelength light (?1) from an incoming wavelength-multiplexed light signal. An observation signal modulating unit (64) modulates the intensity of the branched fixed-wavelength light (?1) with observation information multiplexed by an observation signal multiplex unit (61). A combining unit (65) combines light signals (?2) to (?n) passing through the branching unit (63) and the fixed-wavelength light (?1a) modulated by the observation signal modulating unit (64) into a composite light signal, and outputs it to an optical fiber (12a). Therefore, in each of the plurality of submarine observation apparatus (1 to n), there is no necessity for providing a wavelength-division-multiplexing-transmission optical transmitter which requires high wavelength stability.

Abstract: A wavelength converter for binary optical signals includes an interferometer structure (110) for generating an output signal by modulating a received local signal (LS) according to the modulation of a fUrther received first input signal (IS 1). When such interferometer structures (110) are operated in a standard mode it is known in the art to control the power of the input signal such that the extinction ratio of the output signal is kept minimal. The invention also controls the power of the input signals to achieve the minimal extinction ratio when the wavelength converter and in particular the interferometer structure (110) is operated in a differential mode receiving two input signals.

Abstract: An optical repeater which includes a wavelength converter and a bit rate converter. The wavelength converter converts a wavelength of an optical signal from a first optical network to a wavelength of a second optical network. The bit rate converter converts a bit rate of the optical signal from the first optical network to a bit rate of the second optical network. The optical repeater transmits the optical signal from the first optical network to the second optical network at the converted bit rate and wavelength.

Abstract: A digital control circuit enables/disables the feedback of serial transmissions of an UART receive signal when the G-LINK output port is short circuited in a particular operational mode. In a conventional operational mode, the digital control circuit monitors the state of the UART's Tx output and during an UART transmission, the Rx line normally is used for statistics feedback to set to a high state and eliminate unnecessary or unwarranted UART interrupts generated by the G-LINK circuit. The digital control circuit thus enables the G-LINK signal feedback to the UART when required, thereby maintaining a functionality to identify the unit's operational mode and allows the serial ports of the G-LINK to be configured and utilized during conventional operational modes.

Abstract: An optical pulse regenerator comprising means for broadening the temporal widths and flattening the centre portions of an optical pulse in optical communication using a saturable absorber such as, an unbalanced optical interferometer, and with an optical amplifier.

Abstract: A method for transmitting a packet in a wireless access network based on a wavelength identification code scheme. The method comprises the steps of connecting n number of RNCs (Radio Network Controllers) to one sub-ring where the “n” is a positive integer, and assigning a unique wavelength to each RNC; identifying a packet to be transmitted between the RNCs located within a same sub-ring using the assigned unique wavelength, and transmitting the packet through an SRC (Sub-Ring Controller); connecting m number of SRCs to one main-ring where the “m” is a positive integer, and assigning a unique wavelength to each SRC; and detaching a wavelength identification code from the packet to be transmitted between the RNCs located within different sub-rings, and transmitting the packet having the encapsulated wavelength identification code through an MRC (Main-Ring Controller).

Abstract: A testing device for testing an electronic device is provided. The testing device includes: a deterministic jitter application unit for applying deterministic jitter to a given input signal without causing an amplitude modulation component and supplying the input signal with the deterministic jitter to the electronic device; a jitter amount controller for controlling the magnitude of the deterministic jitter generated by the deterministic jitter application unit; and a determination unit for determining whether or not the electronic device is defective based on an output signal output from the electronic device in accordance with the input signal.

Abstract: Optical signal transmission is improved by reducing the variance in light output level and OSNR by adjusting optical signal intensity and gain tilt, taking SRS influence into consideration.

Abstract: The wavelength converter comprises (1) an optical multiplexer for multiplexing an amplitude-modulated first light and reference light, which is continuous light having a wavelength different from the wavelength of the first light, (2) an optical fiber for propagating the multiplexed light therethrough to generate a third light by a non-linear optical phenomenon, and (3) an optical filter having a pass wavelength range set such that a pulse time width of the third light is 20% or more narrower than a pulse time width of the first light after the third light has passed through the optical filter, or (3?) an optical filter having a pass wavelength range set such that a cross point of an eye pattern of the third light is lower than a cross point of an eye pattern of the first light after the third light has passed through the optical filter.

Abstract: The field of the invention is that of devices for regenerating optical signals. It applies more particularly to systems for high-throughput long distance transmission by optical fibres of digital data. While propagating, optical signals necessarily experience attenuation and degradation of their signal/noise ratio. To compensate for these degradations, wholly-optical regeneration devices are generally used. The object of the invention is to ensure regeneration which in large part eliminates noise, without using auxiliary optical devices. This regeneration is ensured by a structure with saturable optical absorbent comprising an optical cavity of thickness L comprising at least one layer of active material of Henry factor ?H and of maximum absorption variation ?? such that the thickness L equals about 2?/(?H, ??).