Abstract: Disclosed are an optical coupler type filter, and a wavelength stabilizing apparatus of a light source using the same.

Abstract: A tunable dispersion compensator whose passband center wavelength changes when the amount of dispersion compensation is changed is suitably adjusted. The relationship between temperature for keeping the center wavelength constant and the amount of dispersion compensation is stored in advance. After controlling the amount of dispersion compensation to achieve best or optimum transmission quality, the amount of dispersion compensation is converted into temperature in accordance with the stored relationship and, based on that, the temperature is controlled to keep the center wavelength constant.

Abstract: The invention relates to methods and arrangements for channel balancing of a wavelength division multiplexed optical signal. Channel balancing according to the invention is performed by using a resonator that provides a selection region in which a selected channel has a substantially increased poser density relative to channels out of resonance. The selected channel is attenuated a desired amount, i.e. a desired amount of power is removed therefrom, by adjusting the properties of the selection region. In a preferred embodiment, attenuation is achieved by adjusting the selection region such that destructive interference is obtained for the selected channel in a fiber carrying tile multiplexed optical signal.

Abstract: A system for matching a optical filter characteristic of a first filter tunable in wavelength with an optical first signal comprises a modulator for modulating at least a part of the first signal with a modulation signal before being applied to the first filter. An analyzing unit derives a control signal for tuning the first filter by analyzing the modulated first signal after passing the first filter in conjunction with the modulation signal.

Abstract: Provided are a tunable demultiplexer and a tunable laser, having an optical deflector in which a refractive index of a core layer of a deflection pattern region having a predetermined shape varies in response to an external electrical signal so that the optical deflector deflects incident light in the radial direction.

Abstract: A re-configurable optical add-drop multiplexer (OADM) (800) includes a first optical circulator (10), a second optical circulator (30), and a fiber Bragg grating (FBG) (20). The first optical circulator has a first circulator port (11), a second circulator port (12), and a third circulator port (13). The second optical circulator has the same structure as the first optical circulator. The FBG has a first state where it reflects an optical signal with a particular wavelength and passes all other wavelengths, and a second state where all the optical signals pass through it. The signal of the particular wavelength can thus be dropped from the optical signals by reflection of the FBG and output from the third circulator port of the first optical circulator, and a new signal of the same dropped wavelength can be added into the optical signals through a first circulator port (31) of the second optical circulator.

Abstract: An optical demultiplexing device used in an optical monitoring device includes an input port and an output port unit including a plurality of ports, and separates a WDM light of plural channels, which is input from the input port, for each wavelength to output to the output port unit. The output port unit includes a plurality of output port sets each of which includes at least two individual output ports as a set, and crosstalk between adjacent individual output ports in a single output port set is larger than crosstalk between adjacent individual output ports belonging to different output port sets.

Abstract: A reconfigurable multifunctional optical device has an optical arrangement for receiving an optical signal, each having optical bands or channels, and a spatial light modulator for reflecting the at least one optical signal provided thereon. The optical arrangement features a free optics configuration with a light dispersion element for spreading each optical signal into one or more respective optical bands or channels for performing separate optical functions on each optical signal. The spatial light modulator includes a micro-mirror device with an array of micro-mirrors, and the respective optical bands or channels reflect off respective micro-mirrors. The free optics configuration includes a common set of optical components for performing each separate optical function on each optical signal. The separate optical functions reflect off separate non-overlapping areas on the spatial light modulator. The separate optical functions include optical switching, conditioning or monitoring functions.

Abstract: There is provided a fiber Bragg grating devise comprising an FBG mount that is constituted by sequentially stacking a temperature control plate, a base plate, and a mounting plate, and an SSFBG in which a plurality of FBG units of the same constitution and a plurality of phase modulation portions are alternately formed in the same optical fiber. The temperature control plate is constituted by a thermo module and a heat-insulating member. The base plate is fixed in contact with the upper face of the temperature control plate and the mounting plate is in contact with the upper face of the base plate in a state where the mounting plate is able to glide over the upper face of the base plate. The SSFBG is fixed to contact an FBG contact portion that is established on the upper face of the mounting plate.

Abstract: An optical apparatus comprises a planar optical waveguide having at least two sets of diffractive elements. The planar optical waveguide substantially confines in at least one transverse spatial dimension optical signals propagating therein. The two diffractive element sets define an optical resonator that supports at least one resonant optical cavity mode. An optical signal in one of the resonant optical cavity modes is successively incident on the diffractive elements of each of the diffractive element sets.

Abstract: Methods of optical communication and optical communication systems are described. According to a first aspect, a method of optical communication includes providing an optical signal and providing a plurality of data signals. This aspect also includes passing a plurality of desired portions of the optical signal using a plurality of respective optical modulators, the desired portions individually having at least one predefined wavelength. The method also includes optically modulating the desired portions of the optical signal using the respective optical modulators and responsive to respective ones of the data signals and outputting the desired portions of the optical signal to an optical communication medium after the modulating.

Abstract: An optical architecture is provided comprising a plurality of mod/mux units, a master optical distribution hub, a plurality of additional optical distribution hubs, and a plurality of premise stations. Each of the mod/mux units is configured to (i) permit selective modulation of demultiplexed components of a target wavelength band of an optical signal, (ii) multiplex the selectively modulated optical signal, and (iii) direct the multiplexed signal to the master optical distribution hub. The master optical distribution hub is configured to distribute multiplexed signals from respective ones of the mod/mux units to corresponding ones of the plurality of additional optical distribution hubs. Each of the plurality of additional optical distribution hubs comprises an arrayed waveguide grating configured to demultiplex the multiplexed optical signal and distribute respective distinct wavelength portions of the target wavelength band to respective ones of the premise stations.

Abstract: There is provided an attenuator device having a simple configuration and capable of selecting an output of beam of an arbitrary wavelength range from a plurality of output ports. The attenuator device comprises: a plurality of output fibers (1-3 and 1-5) having an end surface serving as an output port; discarding optical fibers (1-2 and 1-4) having an end surface serving as a discarding port and each arranged adjacently to the output optical fiber; a diffraction grating (5) which diffracts an incident beam into various directions according to the wavelength thereof; and a micro mirror array (7) which adjusts the output direction of the diffracted beam for each of the wavelength ranges output from the diffraction grating (5). The micro mirror array (7) adjusts the output direction of the diffracted beam so that a part of the diffracted beam may be output to the output port while the rest being output to the discarding port.

Abstract: An improvement in a wavelength division multiplexer and/or a dense wavelength division multiplexer (WDM/DWDM) is achieved by incorporating an electronically reconfigurable diffraction grating (108). The introduction of the electronically reconfigurable diffraction grating (108), which is typically fabricated using MEMS (microelectromechanical systems) technology, improves the compact design, durability, and dynamic functionality of the WDM/DWDM system.

Abstract: A surface emitting semiconductor laser system having an outcoupling aperture on a central waveguide. At either end of the central waveguide are means for reflecting a plurality of different wavelengths of light such that multiple wavelengths are outcoupled through a single outcoupling aperture. Means are provided by which the different wavelengths can be independently modulated.

Abstract: In one embodiment, an optical device includes a polarization diversity module configured to receive an optical input signal and output a first optical output signal and a second optical output signal having the same polarization state. This helps ensure light beams propagating in the optical device have the same polarization state, thereby mitigating the effects of polarization-dependent loss in the optical device. In one embodiment, the optical device comprises an optical dynamic gain equalizer with a light modulator.

Abstract: A system and method for simultaneous delivery of a plurality of independent blocks of 500 MHz digital broadcast television services, stacking a plurality of RF blocks on a plurality of spectrally sliced WDM optical bands.

Abstract: A wavelength multiplexing processing apparatus for use with a wavelength division multiplexing system is disclosed which uses a single AWG to achieve reduction in cost, size and loss. The wavelength multiplexing processing apparatus includes a waveguide device wherein a plurality of incoming and outgoing waveguides, a first slab waveguide and a plurality of channel waveguides are formed on a substrate, a mirror array device and a lens device. The plane direction angles of reflecting mirrors which reflect optical signal components incoming thereto are set so that reflected light of an optical signal component incoming from one of the plural incoming and outgoing waveguides may go out from one of the plural incoming and outgoing waveguides.

Abstract: The invention relates to a planar lightwave circuit including a pair of opposed concave reflective diffraction gratings sharing the same focal line, which separates first and second slab waveguide regions. The ends of input and output waveguides are positioned along the focal line for launching and receiving light directed by one or both of the diffraction gratings. The invention enables light within in a certain wavelength range to be launched from an input waveguide, directed by a single diffraction grating, and output waveguides, all within a single slab waveguide region, while light within another wavelength range will be directed from one diffraction grating to another for output waveguides in a different slab waveguide region.

Abstract: Optical communication systems include a central station that encodes data transmitted to multiplexing (mux) stations or user stations. The central station also decodes data received from the mux stations or user stations. Encoding and decoding are performed using codes, such as composite codes, that designate sources and destinations for data. The mux stations, user stations, and the central station have address encoders and decoders that use, for example, fiber Bragg gratings to encode or decode optical signals according to a code such as a composite code derived by combining codes from one or more sets of codes. A passive optical network comprises one or more levels of mux stations that use such address decoders and encoders to receive, decode, and encode data for transmission toward a central station or a user station.

Abstract: An optical waveguide to fiber coupler comprises a substrate, a first waveguide and a second waveguide. The first and second waveguides are formed on the substrate and intersect at a right angle. A diffraction grating structure is formed at the intersection of the first and second waveguides, such that, when the coupler is physically abutted with a single mode optical fiber, in operation, a polarization split is obtained that couples orthogonal modes from the single-mode optical fiber into single identical modes in the first and second waveguides. Also, employing the coupler in optical polarization diverse applications provides for implementing a polarization insensitive photonic integrated circuit using such diffraction grating structures, such as, for example, photonic crystals.

Abstract: Method and apparatus are contemplated for receiving from an input, an optical signal in a volume hologram comprising a transfer function that may comprise temporal or spectral information, and spatial transformation information; diffracting the optical signal; and transmitting the diffracted optical signal to an output. A plurality of inputs and outputs may be coupled to the volume hologram. The transformation may be a linear superposition of transforms, with each transform acting on an input signal or on a component of an input signal. Each transform may act to focus one or more input signals to one or more output ports. A volume hologram may be made by various techniques, and from various materials. A transform function may be calculated by simulating the collision of a design input signal with a design output signal.

Abstract: An optical filter, adjustable add-drop-continue module and circuit for bundled cross-connect functionality, wherein the transmission response of the optical filter is varied by changing its temperature, tuning of the filter can be carried out by mechanical pressure or tension, the filter can be used to produce add-drop-continue modules which are suitable both for add-drop operation and for drop-continue operation, and cross-connect modules can be constructed from the optical filters.

Abstract: A wavelength router receives light having a plurality of spectral bands at an input port. Subsets of these spectral bands are directed to output ports. The wavelength router includes an optical train and a routing mechanism. The optical train is disposed between the input port and output ports. It provides optical paths for routing the spectral bands and includes a wave plate for rotation polarization components and a dispersive element disposed to intercept light traveling from the input port. The optical train is configured so that light encounters the dispersive element and the wave plate twice before reaching any of the output ports. The routing mechanism has at least one dynamically configurable routing element to direct a given spectral band to different output ports depending on its state. For routing elements that use an odd number of reflections, the wave plate is a quarter-wave plate. For routing elements that use an even number reflections, the wave plate is a half-wave plate.

Abstract: An optical multiplexer/demultiplexer uses a diffraction grating, capable of multiplexing/demultiplexing lights of narrow wavelength spacing at a short focal distance. To this end, a plurality of output waveguide groups is connected to one end face of a slab waveguide to which an input waveguide group is connected. A diffraction grating in which grating grooves, each including a plurality of reflection planes blazed corresponding to respective arrangement directions of the plurality of output waveguide groups are formed, is disposed on the other end face of the slab waveguide. The arrangements of the respective output waveguide groups are determined, so that diffracted lights of wavelengths different from each other, which are reflected by the reflection planes of the diffraction grating, respectively reach the output waveguides of the plurality of output waveguide groups.

Abstract: There is provided an apparatus for performing, by optical code division multiplex access, at least one of encoding and decoding of wavelength-division-multiplexed light. The apparatus includes: an optical input/output section 203 for handling input/output of the wavelength-division-multiplexed light; and N fiber gratings (where N is an integer equal to or greater than two) 101 to 103, which are in a series connection to the optical input/output section 203. Each of the N fiber gratings has a sampled grating structure having an alternating array of first regions (11 to 14; 21 to 24; and 31 to 34) which provide a refractive index modulation with a relatively large amplitude and second regions (201) which provide a refractive index modulation with a relatively small amplitude, the first and second regions being disposed with a constant period P.

Abstract: End of line dispersion compensation is applied on a sub-band by sub-band basis. Adequate end-of-line dispersion compensation may be provided for high data rate WDM systems even for optical link lengths of 1000 km or more. Dispersion compensating gratings (DCGs) may be used as the dispersion compensating components. There is a great savings in cost and package volume compared to per-channel compensation schemes.

Abstract: An optical add-drop multiplexer successively comprises a first ferrule, a first graded index (GRIN) lens with a bandpass filter attached thereon, an optical crystal, a second GRIN lens, and a second ferrule. An input and an output optical fiber are stationed in the first ferrule, and a dropping and an adding optical fiber are stationed in the second ferrule. An optical multiplexed signal from the input optical fiber is transmitted through the first GRIN lens to the bandpass filter. From the bandpass filter, an optical signal having a wavelength identical to a central wavelength of the bandpass filter is output to the dropping optical fiber, and other optical signals having other wavelengths are coupled with an optical signal from the adding optical fiber having a wavelength identical to the central wavelength of the bandpass filter and are transmitted to the output optical fiber.

Abstract: The invention relates to an optical fiber presenting a core, cladding, and a grating written by irradiation and coupling at least one light mode into the cladding so that it is dissipated therein. The invention proposes causing the mean index to vary progressively along the grating, at least at the ends of the grating. The progressive variation in mean index or in the amplitude of index modulation for writing the grating serves to limit insertion losses to the filter formed by the grating. Analogously, in a written-in grating, the invention provides the equivalent of progressively varying the core size of the fiber for interconnecting two optical fibers presenting different core diameters. The invention is applicable in particular to gain-equalizing filters in WDM transmission systems.

Abstract: The invention proposes a Grouped Optical Add Drop Multiplexer (GOADM) comprising a periodic filter for forming a group of spaced optical wavelengths to be dropped or added.

Abstract: The invention provides a wavelength division demultiplexing apparatus which can reduce the connection loss between an input slab and channel waveguides and can suppress excitation of higher-order mode light to reduce the loss. The apparatus includes a first waveguide for propagating WDM light, a first slab for diffusing the light from the first waveguide, a plurality of channel waveguides having a series of different waveguide lengths with a predetermined difference for receiving and splitting the light from the first slab, a second slab for condensing the split light from the channel waveguides, and a second waveguide for propagating the light from the second slab therein, all formed on asubtrate. The channel waveguides and the first slab are optically connected to each other at a number of nodes greater than the number of nodes at which the channel waveguides and the second slab are connected to each other.

Abstract: The object of the present invention is to provide a compact dispersion slope equalizer by which it is possible to simultaneously recover distorted waveforms of WDM signals by dispersion slope of DSF or NZ-DSF at 1.55 ?m band, and to compensate for the dispersion of various fiber transmission lines having various dispersion values and variation of dispersion value caused by the temperature change or the like. WDM signals distorted by the dispersion slope of the fiber are introduced into an input waveguide, and are demultiplexed by a wavelength demultiplexer into each wavelength component, and pass through lattice-form optical circuits, transversal-form optical circuits, or the combination of these circuits. The dispersion slope of the signals is compensated for by these circuits. The recovered signals are multiplexed by a wavelength multiplexer, and the multiplexed light is outputted at an output waveguide. Arrayed-waveguide gratings can be used as the wavelength demultiplexer and multiplexer.

Abstract: A dispersion compensator having relatively uniform transmission characteristics over the bandwidth of a communication channel. The compensator is designed to process an optical signal corresponding to the communication channel by decomposing that signal into spectral components, routing different components along different optical paths that impart relative delays between the components, and recombining the delayed components spatially and directionally to generate a processed optical signal with reduced chromatic dispersion. In one embodiment, the compensator includes a diffraction grating optically coupled to a mirror array, in which different mirrors receive light corresponding to different communication channels. For each channel, a desired group delay value is produced by selecting the curvature of the corresponding mirror. A compensator employing independently addressable, variable-curvature mirrors enables generation of variable, channel-specific group delays.

Abstract: A bi-directional optical transmission system according to the present invention provides transport of x optical channels over n nodes. The system supports two-way transport of the x channels over a single fiber connecting each of the nodes in sequence. The system is advantageous in that only two optical transmission bands are utilized in order to achieve minimal loss in the separation of bands. The use of only two bands permits the utilization of low-loss wide band thin film optical filters to combine and separate the signals at each node. A reflection port of this filter is used to carry oppositely directed signals of the second band from the bi-directional fiber to an optical amplifier for the second band. An alternate arrangement of the optical filters in the two separate bands is chosen to maximize the optical performance of the overall system and significantly reduce insertion losses.

Abstract: A planar lightwave circuit generalized for handling any given band of multiple bands of a wavelength range, including a first grating element handling a first group of bands; and a second grating element handling a second group of bands. The first and second groups of bands overlap in the wavelength range, and may be spaced apart by a fixed wavelength value. By providing two periodic grating elements handling alternating bands, their free spectral range is allowed to expand, improving their roll-off characteristics. By providing separate inputs for each band, wavelength accuracy can be improved. Device flexibility can be further improved by using switch and interleaver fabrics at the inputs and outputs. The resultant device, generalized to handle any given band within a wavelength range, eliminates the need for separate component design and inventory tracking otherwise necessary.

Abstract: An add-drop multiplexer is described, in one embodiment the add-drop multiplexer includes an optical transmission signal input port adapted to receive a wavelength division multiplexed optical transmission signal, an optical transmission signal output port adapted to output at least a portion of the wavelength division multiplexed optical transmission signal, an add-drop optical channel port adapted to receive an optical add channel and output an optical drop channel, and a wavelength selective optical filter arranged between the optical transmission signal input port, the optical transmission signal output port and the optical add-drop channel port. The wavelength selective optical filter reflects optical channels that will continue through the add-drop multiplexer along a transmission line to the optical transmission signal output port and permits an optical channel that is to be dropped to pass therethrough.

Abstract: Compact systems with reduced insertion loss, and increased switch isolation and switching speed. The switching and/or routing devices utilize a separating sub-system, a switching and/or routing sub-system, and a recombining sub-system.

Abstract: At one side of a substrate, a vertical diffraction grating is formed integrated with the substrate, at the other side of the substrate, one pair or more of fibers are disposed through which either light goes from the vertical diffraction grating or light comes into the vertical diffraction grating, and a lens member is disposed between the fibers and the vertical diffraction grating. At the other side of the substrate, positioning means which positions a plurality of fibers is formed integrated with the substrate, and a space between the vertical diffraction grating and the fibers constitutes a waveguide.

Abstract: An optical filter having at least one optical fiber component and a thermal compensation device which includes a first, second and third member in which the thermal compensation device has a first and a second fixing point, the first, second and third members are made from materials having first, second and third thermal expansion coefficients, the optical fiber component is attached to the thermal compensation device at the first and the second fixing points thus defining a composite thermal expansion. The optical filter is such that the composite thermal expansion compensates for thermal behavior of the optical fiber component.

Abstract: An East-West separable ROADM particularly usable as a programmable N×M optical add/drop multiplexer with an efficient pass through of optical channels in a multi-wavelength communication system. The East-West separable ROADM uses a grating that separates multi-channel optical signals into a plurality of optical channels, and combines a plurality of optical channels into multi-channel optical signals. Programmable mirrors and beam steerers can direct each optical channel to any of a plurality of fibers coupled to the device.

Abstract: A tunable dispersion compensator for the compensation of the chromatic dispersion experienced by a single-channel or multi-channel light signal. The compensator includes a plurality of optical structures such as chirped Bragg gratings or combinations thereof, each having a characteristic dispersion profile. An optical coupling arrangement successively propagates the light signal in each of these structures, so that it accumulates the dispersion compensation effect of each. A tuning device jointly tunes the dispersion profile of each optical structure by applying a same tuning force thereto, preferably a temperature gradient.

Abstract: In an optical device, each of a plurality of radiation sources generates a separate different wavelength output signal to a wavelength locking device wherein a grating device receives the separate wavelength output signals from the plurality of radiation sources. The grating device generates a multiplexed wavelength output signal at a zero diffraction order output port thereof, and resolves separate symmetric wavelength?? and wavelength?? output signals at separate predetermined locations within at least one non-zero diffraction order thereof for each of the radiation sources. Each of a plurality of radiation detectors is coupled to receive a separate one of the symmetric wavelength?? and wavelength?? output signals and generate an output signal representing the magnitude of the received wavelength output signal.

Abstract: The present invention is directed to a bidirectional add/drop multiplexer connected with waveguides at opposite ends thereof, respectively, and adapted to add/drop a channel in forward and reverse directions.

Abstract: The invention provides an optical channel monitor chip with an optical coupler for forming a first intermediate signal and a second intermediate signal, and with an AWG-DWDM demultiplexer which splits the second intermediate signal into the individual optical signal parts of the respective wavelength ranges.

Abstract: Devices, such as node and network elements for use in communications systems, which include a plurality of ports, each having an input and an output, a plurality of splitters corresponding to the port inputs, a plurality of combiners corresponding to the port outputs, a plurality of signal paths between the splitters and the combiners, wherein each of the signal paths includes a signal varying device, and a plurality of protection devices connected between the splitters and the combiners, wherein each of the plurality of protection devices includes a signal varying device and provides a protection path corresponding to a plurality of the signal paths, and wherein at least one splitter has at least one unused output after the signal paths and the protection paths are connected, and wherein at least one combiner has at least one unused input after the signal paths and the protection paths are connected.

Abstract: An array of diffraction grating coupled infrared photodetectors is coupled to corresponding high-speed amplifiers for creating a multiple channel high speed receiver for an optical communication system. Each photodetector includes a three-dimensional diffractive resonant optical cavity formed by a diffraction grating that resonates over a narrow range of wavelengths. By creating different resonant optical cavities, the receiver detects each optical channel individually, thereby simplifying receiver design. The receiver finds ready application in systems based upon high power CO2 lasers and semiconductor lasers such as quantum cascade lasers allowing extremely long line of sight communication, such as between satellites. Other applications include ship to ship or ground to missile communications. These applications will benefit from increased jamming resistance and security.

Abstract: A phased-array device for wavelength division multiplexing/demultiplexing, comprising at least one input channel, a plurality of output channels, and an irregularly sampled array of phase modulators between the input and output channels, the irregular array having a configuration and phase modulation such that effectively only one beam at a given wavelength is focused onto a given output channel. In one embodiment the individual phase modulators are randomly spaced, their relative locations being determined by establishing a set of initially chosen locations, shifting each initial location by a random increment resulting in delay within one wavelength if the initially chosen locations are not sufficiently random, and then adjusting each shifted location a fraction of a wavelength such that the overall phase shift to a desired image point on one of the output channels equals a constant value.

Abstract: The present invention relates to an optical waveguide type grating element and others in structure for decreasing absolute values of chromatic dispersion occurring in selective reflection of each of signal channels in a reflection band. The optical waveguide type grating element is provided with an optical waveguide in which signal light containing a plurality of signal channels spaced at a channel spacing ?i propagates, and a grating which is an index modulation formed over a predetermined range of the optical waveguide. Particularly, the optical waveguide type grating element has a transmittance of ?20 dB or less for each of the signal channels in the reflection band, and has a reflectance of ?20 dB or less for each of signal channels outside the reflection band. Furthermore, a deviation of a group delay time of each of the signal channels in the reflection band, which is caused by reflection in the grating, is 10 ps or less in a wavelength range of (?CH??i×0.375/2) or more but (?CH+?i×0.

Abstract: The object of the present invention is to provide a compact dispersion slope equalizer by which it is possible to simultaneously recover distorted waveforms of WDM signals by dispersion slope of DSF or NZ-DSF at 1.55 ?m band, and to compensate for the dispersion of various fiber transmission lines having various dispersion values and variation of dispersion value caused by the temperature change or the like. WDM signals distorted by the dispersion slope of the fiber are introduced into an input waveguide, and are demultiplexed by a wavelength demultiplexer into each wavelength component, and pass through lattice-form optical circuits, transversal-form optical circuits, or the combination of these circuits. The dispersion slope of the signals is compensated for by these circuits. The recovered signals are multiplexed by a wavelength multiplexer, and the multiplexed light is outputted at an output waveguide. Arrayed-waveguide gratings can be used as the wavelength demultiplexer and multiplexer.

Abstract: An optical module 31 is provided in which a wavelength division element 32 such as an optical multi-layer film or diffraction grating is united between the sides of lens blocks 3 of optical module units 1 and 6 opposed to optical fiber blocks 2. Only light with a wavelength ?i among light (wavelength components: ?1, ?2 . . . ?n) from an optical fiber 41 is transmitted through the wavelength division element 32 and enters an optical fiber 42 of the optical module unit 6. On the other hand, the light (wavelength components: ?1, ?2 . . . ?n??i) reflected at the wavelength division element 32 is taken out of an optical fiber 43 of the optical module unit 1.