Optical router for distributing optical signals

Abstract

The invention relates to an optical router (1) for distributing optical signals, comprising at least three input / output ports (10), each able to be optically connected to a transceiver (2), each input / output port comprising an optical routing system (11) connected to a plurality of optical paths (13), each of the optical paths also being connected to another of the optical routing systems so as to optically connect the input / output port to each of the other input / output ports, the optical routing system being configured to passively direct an optical signal received by the input / output port into one of the optical paths that is chosen according to the wavelength of said optical signal.

Description

[0001] Description

[0002] Title: Optical router for the distribution of optical signals

[0003] Technical field

[0004] The invention relates to the communication of information by optical signals, in particular to optical routing devices for the distribution of optical signals between different optoelectronic systems.

[0005] Prior art

[0006] It is common nowadays for a transmitter / receiver to communicate information to other transmitters / receivers via optical signals.

[0007] When a transmitter / receiver is connected with several other transmitters / receivers to communicate different information depending on each of the other transmitters / receivers, it is usual to use one or more passive optical router(s), also called PON (Passive Optimal Network) router(s).

[0008] A passive optical router (PON) comprises a single input and a plurality of outputs, and makes it possible to distribute an optical signal received by the single input to one or more of the outputs and to transmit the optical signals received by each of the outputs to the single input. The orientation of an optical signal from the single input to one or more of the outputs is carried out by distributing the power of the signal in optical fibers of the passive optical router. There is therefore a significant loss of optical energy depending on the number of divisions necessary to orient the signal from the single input to one or more of the outputs. In addition, the passive optical router (PON) is poorly suited to photonic communication, in fact during such communication, the photons are randomly oriented towards one of the different outputs of the passive optical router (PON).

[0009] When a first transceiver connected to one of the outputs of the passive optical router (PON) seeks to send information to a second transceiver connected to another of the outputs of the passive optical router (PON), then the first transceiver must transmit the information to a relay connected to the single input of the passive optical router (PON) which in turn transmits the information to the second transceiver. The communication of information between two transceivers connected to different outputs of a passive optical router (PON) is therefore complex. In addition, state-of-the-art passive optical routers (PON) are not suitable for transmitting information by successive photons, such a single photon entering through a single input can exit through any of the many outputs.

[0010] Therefore, there is a need to improve passive optical routers to overcome the above-mentioned problems. In particular, there is a need for an optical router for communicating information between different transmitters / receivers, the communication being simple to implement and having low energy loss.

[0011] The aim of the invention is to meet, at least in part, this need.

[0012] Statement of the invention

[0013] To this end, the invention relates to an optical router for distributing optical signals, comprising at least three input / output ports, each adapted to be optically connected to a transmitter / receiver configured to transmit and receive optical signals according to a plurality of different wavelengths, each input / output port comprising an optical routing system connected to a plurality of optical paths, internal to the optical router, each of the optical paths also being connected to another of the optical routing systems so as to optically connect the input / output port to each of the other input / output ports, the optical routing system being configured to passively direct an optical signal received by the input / output port into one of the optical paths chosen as a function of the wavelength of said optical signal,the optical path through which an optical signal of a given wavelength is directed from a first input / output port to a second input / output port being the same optical path as that taken by an optical signal of the given wavelength from the second input / output port to the first input / output port.,

[0014] For the purposes of the present invention, the term "optical path" means the path intended to be followed by an optical signal. Thus, an optical path may comprise the path intended to be followed by the light beam of the optical signal in a transparent medium. An optical path may comprise one or more waveguides in which the optical signals are intended to circulate. Preferably, the waveguides are optical fibers or channel guides. More preferably, the channel has a rectangular base, preferably square, with a side length between 0.020 μm and 5 μm for example, preferably between 0.15 μm and 5 μm. The channel of the channel guide may be in ribbon, surface-inscribed or buried.

[0015] For the purposes of the present invention, the term "optical signal" means a photon, a series of photons or a light wave.

[0016] Each optical routing system is connected to at least Nl optical paths, N being equal to the number of input / output ports of the optical router.

[0017] The optical router according to the present invention advantageously allows each of the transmitters / receivers connected thereto to communicate directly with each other without relays, without the optical signals interfering with each other and with little energy loss. Communication between the different transmitters / receivers is thus greatly facilitated. Since there is little loss of photons during communication between a transmitter / receiver and another transmitter / receiver, the optical router according to the present invention is particularly suitable for communication by photon polarization and / or by entangled photons. Furthermore and advantageously, each of the transmitters / receivers is connected to only a single input / output port of an optical router according to the present invention, the optical router is therefore simple to use.

[0018] The optical router may include more than three input / output ports, preferably more than ten.

[0019] Optical routing systems can be configured to passively steer optical signals of wavelength in the ultraviolet, visible or infrared, for example between 169 nm and 14 pm.

[0020] An optical routing system may be configured to passively and simultaneously direct optical signals to a single optical path for a plurality of different wavelengths, for example for wavelengths within a wavelength band of predefined width. Thus, the optical router according to the present invention enables information communication between two transmitters / receivers with optical signals of different wavelengths sent simultaneously, which may increase the speed of information transmission.

[0021] Preferably, at least one, preferably each, of the optical routing systems comprises one or more switches for directing an optical signal according to its wavelength, each switch being selected from: a prism of transparent dispersive material,

[0022] - a resonator coupler comprising first and second waveguides and at least one ring resonator arranged between the first and second waveguides, the ring resonator being configured to transmit an optical signal from the first waveguide to the second waveguide, and vice versa, depending on the wavelength of the optical signal,

[0023] - an optical coupler comprising two waveguides comprising a section in which the two waveguides are brought closer to each other so as to transmit an optical signal from one of the waveguides to the other of the waveguides as a function of the wavelength of the optical signal,

[0024] - a Bragg filter inclined with respect to the direction of propagation of the incident signal and configured to transmit in the direction of propagation of the incident signal or reflect in a direction different from that of propagation of the incident signal, an incident optical signal as a function of its wavelength

[0025] - a Bragg grating, preferably inscribed in a waveguide.

[0026] The refractive indices of the materials used for successive Bragg filters or for successive resonator couplers can be chosen according to the width of the wavelength band for which an optical routing system passively directs optical signals towards the same optical path.

[0027] The prism may be coated with at least one anti-reflective layer. This helps limit optical energy losses due to unwanted reflections caused by changes in refractive index when the optical signal is oriented.

[0028] The resonator coupler may comprise a plurality of ring resonators arranged between the first and second waveguides such that the transmission of an optical signal from the first waveguide to the second waveguide, and vice versa, is carried out by passing said optical signal through each of the ring resonators. The wavelength for which the ring resonators transmit an optical signal may be the same for each of the ring resonators. The ring resonators may be identical.

[0029] The resonator coupler may comprise waveguides between each of the ring resonators, said waveguides being connected to the first waveguide. Said waveguides thus make it possible to recombine together towards the same output an optical signal not transmitted by some of the ring resonators. Preferably, the length of said waveguides is adapted so as to avoid destructive interference during the recombination of the optical signals.

[0030] Preferably, at least one, preferably each, of the optical routing systems comprises first and second groups of switches configured to passively direct an optical signal, emitted by the transmitter / receiver connected to the input / output port, to the same other input / output port chosen as a function of the wavelength of said optical signal, said optical routing system comprising a polarizing filter arranged upstream of all the switches, said polarizing filter being configured to orient said optical signal towards the first group of switches if said optical signal is according to a first polarization, for example vertical, or towards the second group of switches if said optical signal is according to a second polarization perpendicular to the first polarization, for example horizontal,said optical routing system comprising a polarization rotator configured to rotate by 90° the polarization of the optical signal arranged between the polarizing filter and the second group of switches. Thus, the optical routing system is suitable for directing an optical signal regardless of its polarization and the switches chosen. This is particularly interesting when at least one of the switches chosen only operates with electromagnetic waves with a given polarization, for example trans-electric, for example said switch is a resonator coupler.,

[0031] By "upstream of the switch assembly" it is meant that the polarizing filter is arranged so as to be between the switch assembly and a transmitter / receiver, when the latter is connected to the input / output port.

[0032] According to a variant, each of the optical routing systems comprises first and second switch groups, and the optical paths at the output of the first switch group, respectively of the second switch group, of an optical routing system are connected to the first switch groups, respectively to the second switch groups, of the other optical routing systems.

[0033] According to another variant, the first and second groups of switches are configured to passively direct an optical signal, emitted by the transmitter / receiver connected to the input / output port, towards the same optical path chosen according to the wavelength of said optical signal, the optical routing system comprising, for each optical path, a polarizing filter between all the switches and said optical path, each of the polarizing filters being configured to direct an optical signal towards the first group of switches, if said optical signal is according to the first polarization, or towards the second group of switches, if said optical signal is according to the second polarization, said optical routing system comprising a polarization rotator configured to rotate by 90° the polarization of the optical signal arranged between each of said polarizing filters and the second group of switches.

[0034] According to another preferred variant, each of the optical routing systems comprises first and second groups of switches configured to passively direct an optical signal, emitted by the transmitter / receiver connected to the input / output port, to the same other input / output port chosen according to the wavelength of said optical signal, said optical routing system comprising a polarizing filter arranged upstream of all the switches, said polarizing filter being configured to orient said optical signal towards the first group of switches if said optical signal is according to a first polarization, for example vertical, or towards the second group of switches if said optical signal is according to a second polarization perpendicular to the first polarization, for example horizontal,said optical routing system comprising a polarization rotator configured to rotate by 90° the polarization of the optical signal arranged between the polarizing filter and the second group of switches, and, the optical paths at the output of the first group of switches, respectively of the second group of switches, of an optical routing system are connected to the second groups of switches, respectively to the first groups of switches, of the other optical routing systems. This preferred variant also corresponds to a crossed-type optical router. Preferably, the polarizing filters are made of birefringent crystals, for example prisms or blades made of birefringent materials.,

[0035] The couplings between the polarizing filters and the waveguides are made in such a way as to allow the transmission of an optical signal independently of its wavelength.

[0036] The waveguides of the switches may be optical fibers or channel guides. Preferably, the channel has a rectangular base, preferably square, with a side length between 0.020 pm and 5 pm for example, preferably between 0.15 pm and 5 pm. The channel of the channel guide may be ribbon, surface-inscribed or buried.

[0037] At least one of the input / output ports may comprise a connector to which a transceiver is intended to be connected, the connector being configured to optically connect a transceiver, possibly extended by an optical fiber or a channel guide, to the optical routing system of said input / output port.

[0038] Preferably, at least one of the optical routing systems includes connections configured to optically connect the switches to each other and / or to optically connect the switches to the connector.

[0039] The connections may be light rays passing through air or vacuum, optical fibers or channel guides. Preferably, the channel of the channel guide has a rectangular base, preferably square, with a side length between 0.020 pm and 5 pm for example, preferably between 0.15 pm and 5 pm. The channel of the channel guide may be ribbon, surface-inscribed or buried.

[0040] At least one of the connections may comprise, at at least one of its ends, a mode converter, configured to switch from single-mode guidance to multi-mode guidance or vice versa.

[0041] At least one of the connections may comprise at least one of its ends a joint, also called a "butt coupling" in English, for optically connecting an optical fiber to a channel guide, the optical fiber belonging to a switch or to the connector and the channel guide belonging respectively to the connector or to a switch. At least one of the connections may comprise at the end of an optical fiber a lens for optically connecting said optical fiber to a channel guide, by focusing the optical signal on one end of the channel, the optical fiber belonging to a switch or to the connector and the channel guide belonging respectively to the connector or to a switch.

[0042] The optical routing systems may include at least one lens arranged between one of the connections and one of the prisms or Bragg filters, the lens being configured to direct light rays exiting the connection into a parallel-ray light beam toward the prism or Bragg filter and vice versa.

[0043] The optical router may include a housing in which the optical routing systems and optical paths are housed.

[0044] The optical router may comprise at least two boxes, the optical routing systems of a portion of the input / output ports being housed in one of the boxes and the optical routing systems of another portion of the input / output ports being housed in the other of the boxes. Preferably, the optical router comprises at least one multiplexer configured so that at least two of the optical paths, intended to transport optical signals of different wavelengths and connecting together two optical routing systems housed in boxes different from each other, are merged along their portion between the two boxes.

[0045] The optical router may be configured to modify the polarization of the transmitted optical signal, such that the polarization of said optical signal at the output of the optical router is perpendicular to the polarization of said optical signal at the input of the optical router. Such an optical router is called a cross-type optical router or cross-type optical router. Advantageously, this facilitates the use of transmitters / receivers comprising a light source and a complex detector or absorber. In particular, a cross-type optical router facilitates the use of transmitters / receivers configured to transmit an optical signal in a first polarization, for example linear and vertical, and to receive an optical signal in a second polarization, the second polarization being perpendicular to the first polarization, for example linear and horizontal.Other pairs of complementary polarizations may be used, for example the first polarization may be circular in a first sense and the second polarization may be circular in a second sense, the second sense being opposite to the first sense.

[0046] The crossed optical router may comprise a polarization rotator arranged on each of the optical paths linking two routing systems and being configured to rotate by 90° the polarization of an optical signal circulating in the corresponding optical path. These polarization rotators are preferred when the optical routing systems are adapted for any kind of polarization, for example if these switches are tilted Bragg filters and / or prisms. Said polarization rotators may comprise half-wave plates or Faraday rotators.

[0047] Alternatively, the cross optical router may comprise a polarization rotator arranged in each of the input / output ports upstream of the set of switches of the corresponding input / output port, each polarization rotator being configured to rotate by 45° the polarization of an optical signal circulating in the corresponding optical path. Thus, when an optical signal is transmitted through said cross optical router, it passes through two polarization rotators according to the above, which rotates by 90° in total the polarization of said optical signal. These polarization rotators are preferred when the switches of the cross optical router are only adapted to a single type of polarization, for example trans-electric, for example if these switches are resonator couplers. Said polarization rotators may comprise Faraday rotators or chiral materials.

[0048] According to a preferred alternative, at least one, preferably each, of the optical routing systems comprises first and second groups of switches configured to passively direct an optical signal, emitted by the transmitter / receiver connected to the input / output port, to the same other input / output port chosen according to the wavelength of said optical signal, said optical routing system comprising a polarizing filter arranged upstream of all the switches, said polarizing filter being configured to orient said optical signal towards the first group of switches if said optical signal is according to a first polarization, for example vertical, or towards the second group of switches if said optical signal is according to a second polarization perpendicular to the first polarization, for example horizontal,said optical routing system comprising a polarization rotator configured to rotate by 90° the polarization of the optical signal arranged between the polarizing filter and the second group of switches. Thus, the optical routing system is suitable for directing an optical signal regardless of its polarization and the switches chosen. This is particularly interesting when at least one of the switches chosen only works with electromagnetic waves with a given polarization, for example trans-electric, for example said switch is a resonator coupler.,

[0049] The invention also relates to an optical communication system comprising at least one optical router as described previously and, for each optical router, a plurality of transmitters / receivers configured to transmit and receive optical signals according to a plurality of different wavelengths, each of the transmitters / receivers being connected to one of the input / output ports of the optical router.

[0050] Preferably, at least one, preferably each, of the transceivers is configured to transmit and receive optical signals according to a plurality of different wavelengths at least equal to N minus one, N being equal to the number of input / output ports of the optical router to which the transceiver is connected.

[0051] At least one of the transceivers may be configured to transmit and receive optical signals at a plurality of different wavelengths at least equal to N, where N is equal to the number of input / output ports of the optical router to which the transceiver is connected. This is particularly advantageous if the number N is odd, for example if N is equal to 3, because the optical communication system may be designed so that the transceiver may be connected to any of the input / output ports of the optical router.

[0052] The optical communication system may comprise at least two optical routers and an active router connected to both optical routers, the active router being configured to receive an optical signal, comprising information, from a transceiver connected to one of the two optical routers and to transmit an optical signal, comprising said information, to another transceiver connected to the other of the two optical routers. Preferably, the information comprises an indication, for example the identity, of the other transceiver intended to receive said information. At least one of the transceivers may comprise a plurality of lasers, each laser being configured to transmit a laser optical signal of a wavelength different from the other lasers.Preferably, said transmitter / receiver is configured such that the laser optical signals are directed to a single optical output of said transmitter / receiver, the optical output being connected to the corresponding input / output port. More preferably, said optical output is also an optical input configured to receive optical signals from the corresponding input / output port.

[0053] The communication system can be used for communication by entangled photons as, for example, described in patent applications FR3125658 A1 and FR3125659A1.For this, at least one, preferably each, of the transmitters / receivers may comprise first and second complex absorbers and a source configured to generate at least one pair of entangled photons comprising a first photon emitted on a first propagation path connected to the first complex absorber and a second photon emitted on a second propagation path connected to the input / output port connected to said transmitter / receiver, the first complex absorber being configured to absorb the first photon in a polarization state chosen from two complementary polarizations, the second complex absorber being configured to collect the photons emitted by another of the transmitters / receivers and / or coming from the optical router, to demultiply said photons and to measure the average polarization of the photons resulting from the demultiplication.

[0054] Thus, the communication system is suitable for the communication of quantum information by entangled photons, the wavelength of the entangled photon pair is chosen according to F transmitter / receiver with which the entangled photon source and the first complex absorber wish to communicate. In other words, the second photon is directed according to its wavelength by the optical router to F transmitter / receiver with which the entangled photon source and the first complex absorber wish to communicate.

[0055] The communication system according to the invention advantageously makes it possible to simplify communication by entangled photons between numerous transmitters / receivers according to the above, and in a more compact manner. In particular, the entire communication system can be integrated into a limited number of housings. In particular, each transmitter / receiver can group all of its components in a single housing. The first propagation path and / or the second propagation path can comprise an optical fiber. Preferably, the length of the first propagation path is twice the length of the second propagation path between the transmitter / receiver and the router for each of the transmitters / receivers comprising first and second complex absorbers and a source of entangled photons. Thus, the transport time of the first and second entangled photons between their emission and their reception is substantially the same.The first propagation path may, for example, be arranged along the second propagation path on the portion between the entangled photon source and the router, then arc back to the first complex absorber while being arranged along the same second propagation path. In another example, the first propagation path is coiled and arranged inside or outside the transmitter / receiver housing.

[0056] Preferably, the transmitters / receivers are each connected to the optical router by an optical fiber of the same length.

[0057] Preferably, the optical router is of the crossed type and the optical communication system comprises, for each of said transmitter(s) / receiver(s), a polarizing filter, called an internal polarizing filter, preferably a birefringent crystal, arranged on the propagation path linked to the input / output port of the transmitter / receiver; the polarizing filter being configured to orient an optical signal emitted by the transmitter / receiver, in particular by the source, towards the optical router, if said optical signal is in a first polarization, and to orient an optical signal coming from the optical router towards the second complex absorber, if said signal is in a second polarization perpendicular to the first polarization.Preferably, the optical signal emitted by the source consists of entangled photons with a fixed polarization, for example linear and vertical, allowing it to be directed towards the input / output port to which the transmitter / receiver is connected through said internal polarizing filter.

[0058] For functional reasons, the optical path from the source of entangled photons to the target transmitter / receiver receiving the information is preferably longer than the optical path between the source of entangled photons and the first complex absorber of the transmitter / receiver used to send the information. For this purpose, an additional optical fiber, for example 5 to 10 cm long, may be inserted in the housing of the transmitter / receiver between said internal polarizing filter and the second complex absorber.

[0059] In one variant, the router used is not of the crossed type, each transmitter / receiver then preferably being provided with a 45° polarization rotator such as a Faraday rotator.

[0060] The optical communication system may comprise a polarizing device on the second propagation path at the output of each of the transmitters / receivers and at each input / output port of the optical router, the polarizing device being configured to transform a linearly polarized optical signal into a circularly polarized optical signal. Advantageously, this makes it possible to overcome constraints concerning the direction of polarization of the photons in the optical fibers connecting the transmitters / receivers to the optical router.

[0061] The invention also relates to an optical communication method comprising the use of an optical communication system as described previously, the use comprising the transmission of an optical signal by one of the transmitters / receivers, called the first transmitter / receiver, and the reception of the optical signal by at least one other of the transmitters / receivers, called the second transmitter / receiver.

[0062] The first and second transceivers may be connected to a first electronic component, respectively a second electronic component, the use comprising communicating information from the first electronic component to the second electronic component by transmitting an optical signal from the first transceiver and receiving said optical signal by the second transceiver. The first and second electronic components may be processors and / or memory blocks and / or network peripherals and / or computer peripherals.

[0063] Preferably, the use comprises a calibration step during which at least one of the transmitters / receivers, called the transmitter / receiver to be calibrated, sends at least one optical signal at a given wavelength, then the optical signal is received by another of the transmitters / receivers which sends in return an optical response signal indicating its identity at the same said given wavelength, and the transmitter / receiver to be calibrated then records the identity of the other transmitter / receiver and associates it with the given wavelength. Preferably the optical signal emitted by the transmitter / receiver to be calibrated indicates the identity of said transmitter / receiver and the other transmitter / receiver records the identity of the transmitter / receiver to be calibrated and associates it with the given wavelength.

[0064] During the calibration step, the transceiver to be calibrated may send a plurality of optical signals, each at a given wavelength different from the other optical signals, such that the transceiver to be calibrated records the identity and associated given wavelength of each of the other transceivers connected to the optical router. The sending of the plurality of optical signals may be simultaneous.

[0065] Brief description of the drawings

[0066] Other advantages and characteristics will become more apparent upon reading the detailed description, given for illustrative and non-limiting purposes, with reference to the following figures:

[0067] [Fig 1] Figure 1 is a diagram showing an optical communication system according to the invention;

[0068] [Fig 2 A] [Fig 2B] Figures 2 A and 2B are each a diagram showing an embodiment of an optical router according to the invention;

[0069] [Fig 3A] Figure 3A is a diagram showing an embodiment of an optical routing system for an optical router according to Figure 2A, the optical routing system comprising a prism of dispersive material;

[0070] [Fig 3B] [Fig 3 C] Figures 3B and 3C are simulations of an optical routing system for an optical router according to the invention, the optical routing system comprising a prism made of dispersive material;

[0071] [Fig 4] Figure 4 is a diagram showing another embodiment of an optical routing system for an optical router according to Figure 2A, the optical routing system comprising two resonator couplers;

[0072] [Fig 5 A] [Fig 5B] [Fig 5C] Figures 5 A, 5B and 5C are each a diagram showing one embodiment of a resonator coupler for an optical routing system according to Figure 4; [Fig 6] Figure 6 is a diagram showing another embodiment of an optical routing system for an optical router according to Figure 2A, the optical routing system comprising two optical couplers;

[0073] [Fig 7] Figure 7 is a diagram showing an optical coupler for an optical routing system according to Figure 6;

[0074] [Fig 8] Figure 8 is a curve representing the ratio of the output power to the input power of an optical signal after transmission of the optical signal by an optical coupler according to Figure 7 as a function of the wavelength;

[0075] [Fig 9] Figure 9 is a diagram showing another embodiment of an optical routing system for an optical router according to the invention, the optical routing system comprising a plurality of optical couplers connected to each other in the form of a tree structure;

[0076] [Fig 10] Figure 10 is a diagram showing another embodiment of an optical routing system for an optical router according to the invention, the optical routing system comprising a plurality of inclined Bragg filters arranged one after the other;

[0077] [Fig 11] Figure 11 is a diagram showing an optical communication system according to the invention;

[0078] [Fig 12 A] [Fig 12B] Figures 12A and 12B are each a diagram showing an embodiment of an optical router according to the invention, the optical router comprising two boxes separated from each other;

[0079] [Fig 13] Figure 13 is a diagram showing an embodiment of an optical routing system for an optical router according to the invention, the optical routing system comprising first and second groups of switches, polarizing filters and polarization rotators;

[0080] [Fig 14] Figure 14 is a diagram representing an optical communication system according to the invention for quantum communication by entangled photons integrating polarizing filters between the source of the entangled photons and the optical router;

[0081] [Fig 15] Figure 15 is a diagram showing a first example of a cross-type optical router for the optical communication system shown in Figure 14; [Fig 16] Figure 16 is a diagram showing a second example of a cross-type optical router for the optical communication system shown in Figure 14;

[0082] [Fig 17] Figure 18 is a diagram showing a third example of a cross-type optical router for the optical communication system illustrated in Figure 14;

[0083] [Fig 18] Figure 18 is a schematic diagram showing a polarizing device configured to transform a linearly polarized optical signal into a circularly polarized optical signal.

[0084] Detailed description

[0085] Figure 1 illustrates an optical communication system 100 according to the invention, this system comprises an optical router 1 according to the invention and a plurality of transmitters / receivers 2.

[0086] Each of the transmitters / receivers 2 is connected to an electronic component 4, and is also optically connected to an input / output port 10 of the optical router 1 via an optical fiber 3. Thus, the transmitters / receivers 2 connected to the optical router 1 can communicate with each other, the optical router 1 distributing the optical communication signals between said transmitters / receivers 2, which allows the transmission of information between the different electronic components 4.

[0087] Figure 2A illustrates a first example of an optical router 1 according to the invention. The optical router 1 comprises four input / output ports 10.1-10.4, each comprising an optical routing system 11.1-11.4 and a connector 12.1 - 12.4 adapted for connecting an optical fiber 3.

[0088] Each optical routing system 11.1-11.4 is optically connected to each of the other optical routing systems 11.1-11.4 by optical paths 13a-13c. The optical paths 13a, 13b and 13c are intended to transmit optical signals of wavelength X a , b and Xc, respectively. That is, optical routing systems 11.1-11.4 direct an optical signal of wavelength X a , Xb or Xc, respectively, in an optical path 13a, 13b or 13c. The optical router 1 may comprise a housing 14 in which the optical paths 13a-13c and the optical routing systems 11.1-11.4 are housed.

[0089] For example, an optical signal of wavelength X areceived by the input / output port 10.1, respectively 10.3, will be directed by the optical routing system 11.1, respectively 11.3, into an optical path 13a which will transmit said optical signal to the input / output port 10.2, respectively 10.4. Conversely, an optical signal of wavelength A a received by the input / output port 10.2, respectively 10.4, will be directed by the optical routing system 11.2, respectively 11.4, into an optical path 13a which will transmit said optical signal to the input / output port 10.1, respectively 10.3. Table 1 below represents the wavelength assignment for communication between the different input / output ports 10.1-10.4 of the optical router 1 according to Figure 2A.

[0090] [Table 1]

[0091] As shown in Table 1, it is sufficient that a transceiver 2 connected to one of the input / output ports 10.1-10.4 of the optical router 1 is configured to transmit and receive optical signals according to at least three different wavelengths for said transceiver 2 to be able to transmit or receive optical signals to or from each of the other input / output ports 10.1-10.4 of the optical router 1.

[0092] Figure 2B illustrates a second example of an optical router 1 according to the invention. The optical router 1 is similar to that of Figure 2A except that it comprises three input / output ports 10.1-10.3, each comprising an optical routing system 11.1-11.3 and a connector 12.1-12.3 adapted for connecting an optical fiber 3.

[0093] The optical router 1 also includes optical paths 13a, 13b and 13c for transmitting optical signals of wavelength A a , Ab and A c, respectively. The optical routing system 11.1 directs an optical signal of wavelength X a , respectively Xb, in the optical path 13a, respectively 13b. The optical routing system 11.2 directs an optical signal of wavelength X a , respectively X c , in the optical path 13a, respectively 13c. The optical routing system 11.3 directs an optical signal of wavelength Xb, respectively X c , in the optical path 13b, respectively 13c.

[0094] Table 2 below represents the wavelength assignment for communication between the different input / output ports 10.1-10.3 of the optical router 1 according to Figure 2B.

[0095] [Table 2]

[0096] As shown in Table 2, it is sufficient for a transmitter / receiver 2 connected to one of the input / output ports 10.1-10.3 of the optical router 1 to be configured to transmit and receive optical signals according to at least two different wavelengths for said transmitter / receiver 2 to be able to transmit or receive optical signals to or from each of the other input / output ports 10.1-10.3 of the optical router 1. However, and unlike the optical router 1 of Figure 2 A, the wavelengths used for communication depend on the input / output port 10.1-10.3 to which the transmitter / receiver 2 is connected.

[0097] In each of the embodiments of Figures 2A and 2B, the optical paths 13 may be waveguides, for example channel guides or optical fibers. Preferably, the waveguides 13 do not cross. For example, the waveguides 13 may overlap each other. Furthermore, the connectors 12 are only preferred, the transmitters / receivers 2 may be optically connected to the optical routing systems 11 directly, that is to say by an optical beam in the open air or by an optical guide of a transmitter / receiver 2 welded to the optical router 1.

[0098] Of course, the number of input / output ports 10 can be any number greater than or equal to three. For example, an optical router 1 according to the invention can comprise six input / output ports 10.1-10.6, or even eight input / output ports 10.1-10.8, or even ten input / output ports 10.1-10.10, or even more than ten input / output ports. Tables 3, 4 and 5 below represent, respectively, the wavelength assignments for communication between six input / output ports 10.1-10.6, eight input / output ports 10.1-10.8, and ten input / output ports 10.1-10.10 of an optical router 1 according to the invention.

[0099] [Table 3] [Table 4]

[0100] [Table 5]

[0101] Figure 3A illustrates a first embodiment of an optical routing system.

[0102] 11. The optical routing system 11 comprises a prism 14 made of transparent dispersive material and connections 20.

[0103] One of the connections 20 optically connects the connector 12 to the prism 14 so that when a transmitter / receiver 2 connected to the connector 12 emits an optical signal, it is transmitted to the prism 14 in the form of a light beam F. The other connections 20 are each optically connected to one of the optical paths 13a-13c.

[0104] A lens 21 is arranged at the output of the connection 20 between the prism 14 and the connector

[0105] 12. This lens 21 is configured to direct the light rays exiting the connection 20 into a light beam with parallel rays towards the prism 14 and, conversely, to direct the parallel light rays exiting the prism 14 into said connection 20.

[0106] Depending on the wavelength of the optical signal, the light beam F will be deflected more or less by the prism 14. Thus, the prism 14 directs the light beam F into one of the connections 20 connected to one of the optical paths 13 a- 13 c depending on the wavelength of the optical signal.

[0107] For example, as illustrated in Figure 3 A, the optical signal is of wavelength Xb and the prism 14 deflects the light beam F towards the connection 20 connected to the optical path 13b.

[0108] Conversely, according to the principle of reverse light return, an optical signal coming from one of the optical paths 13 a-13 c will be directed towards the connection 20 connected to the connector 12. Preferably, the connections 20 are configured so that the optical signal S propagates in the form of a plane wave in said connections 20.

[0109] Illustrated in Figure 3B is a computer simulation of an optical routing system 11 comprising a prism 14 made of a transparent dispersive material coated with an anti-reflective layer. The prism 14 is configured to direct optical signals of wavelengths X a , respectively Xb, at the output of a connection 20 to an optical path 13a, respectively an optical path 13b. In the simulation presented, an optical signal of wavelength X a is directed in the form of a light beam F towards the optical path 13a.

[0110] The optical paths 13a and 13b are each waveguides whose width is substantially equal to three times the wavelength of the optical signals which they are intended to transmit.

[0111] Illustrated in Figure 3C is a computer simulation of an optical routing system 11 comprising a prism 14 made of a transparent dispersive material coated with an antireflection layer. The prism 14 is configured to direct optical signals of wavelengths, respectively, X a , Xb, Xc, Xa, Xe, Xf and X g at the output of a connection 20 to, respectively, an optical path 13a, an optical path 13b, an optical path 13c, an optical path 13d, an optical path 13e, an optical path 13f and an optical path 13g. In the simulation presented, an optical signal of wavelength Xa is directed in the form of a light beam F towards the optical path 13d.

[0112] The optical paths 13a to 13g are each waveguides whose width is substantially equal to fifteen times the wavelength of the optical signals which they are intended to transmit.

[0113] Figure 4 illustrates a second embodiment of an optical routing system 11. The optical routing system 11 comprises first 15 and second 15' resonator couplers and connections 20.

[0114] The connections 20 are here channel-inscribed waveguides. The connection 20 connected with the connector 12 comprises a joint 22 welded at its end connected to the connector 12. The joint 22 allows the transmission of an optical signal from the channel-inscribed waveguide 20 to the connector 12, and vice versa, with a signal loss of between 10% and 90%. The first resonator coupler 15 comprises first 151 and second 152 channel-inscribed waveguides, and a ring resonator 150 arranged between the first 151 and second 152 waveguides. The ring resonator 150 is configured to transmit an optical signal from the first waveguide 151 to the second waveguide 152 if the wavelength of the optical signal is A a, and, to pass an optical signal without transmission from one waveguide to another if the wavelength of the optical signal is Ab or A c .

[0115] The second resonator coupler 15' comprises first 151' and second 152' channel-written waveguides, and a ring resonator 150' arranged between the first 151' and second 152' waveguides. The ring resonator 150' is configured to transmit an optical signal from the first waveguide 151' to the second waveguide 152' if the wavelength of the optical signal is Ab, and to pass an optical signal without transmission from one waveguide to another if the wavelength of the optical signal is A a or Ac.

[0116] Thus, when an optical signal is emitted by a transmitter / receiver 2 connected to the connector 12, it will be transmitted by the first resonator coupler 15, or respectively by the second resonator coupler 15', towards the optical path 13a, or respectively the optical path 13b, if the wavelength of the optical signal is A a , respectively Ab. If the wavelength of the optical signal is A c , the optical signal will be directed to the optical path 13c without transmission by the first 15 and second 15' resonator couplers.

[0117] Conversely, according to the principle of reverse light return, an optical signal from one of the optical paths 13a, 13b or 13c will be directed to the connection 20 connected to the connector 12 if the wavelengths of the lights are respectively A a , Ab or Ac.

[0118] Figures 5A to 5D illustrate different embodiments of resonator couplers 15.

[0119] The resonator coupler 15 illustrated in Figure 5 A comprises first 151 and second 152 waveguides optically coupled to a ring resonator 150. A person skilled in the art usually knows how to optically couple a ring resonator 150 to a waveguide 151, or 152. In particular, he knows that the optical coupling depends on the radius of curvature r of the ring resonator 150 as it approaches the waveguides 151 and 152, on the distance d between the ring resonator 150 and the waveguides 151 and 152 and on the refractive index of the medium between the ring resonator 150 and the waveguide 151, or 152. The ring resonator 150 comprising two semicircles of radius r spaced apart from each other by segments of length L.The radius r and the length L are chosen so that the perimeter of the ring resonator 150 multiplied by its refractive index is a multiple plus half of the wavelength X for which an optical signal is transmitted from the waveguide 151 to the waveguide 152. Thus, the ring resonator 150 transmits optical signals of wavelength X from the first waveguide 151 to the second waveguide 152 and vice versa. The ring resonator 150 can also be a circle of radius r, in other words, the length L of the segments is equal to 0 pm.

[0120] The inventor has determined that for waveguides 151 and 152 and for a ring resonator 150 with a refractive index equal to 3, with a distance d between the ring resonator 150 and the waveguides 151 and 152 equal to 0.2 pm and for a refractive index of the transparent medium between the ring resonator 150 and the waveguides 151 and 152 equal to 1, for example the transparent medium being air:

[0121] - the ring resonator 150 will transmit an optical signal of wavelength A a equal to 1.33 pm if it is in the form of a circle with radius r equal to 1.62 pm;

[0122] - the ring resonator 150 will transmit an optical signal of wavelength Xn equal to 1.57 pm if it is in the form of a circle of radius r equal to 1.67 pm;

[0123] - the ring resonator 150 will transmit an optical signal of wavelength X c equal to 1.11 pm if it is in the form of a circle with radius r equal to 1.65 pm;

[0124] - the ring resonator 150 will transmit an optical signal of wavelength Ai equal to 1.77 pm if it is in the form of a circle of radius r equal to 2.72 pm.

[0125] For each of the dimensions described in the preceding paragraph, the ring resonator 150 will not transmit an optical signal of wavelength X eequal to 1.885 pm. Thus, an optical routing system 11 according to the invention may comprise a succession of four resonator couplers 15, each comprising a ring resonator 150 according to the preceding dimensions. Such an optical routing system 11 is adapted to direct optical signals of wavelengths, respectively, X a , Xb, X c , Xd and Xe to, respectively, an optical path 13a, an optical path 13b, an optical path 13c, an optical path 13d and an optical path 13e.

[0126] The resonator coupler 15 illustrated in Figure 5B comprises a first waveguide 151 optically coupled to a first ring resonator 150 and a second waveguide 152 optically coupled to a second ring resonator 150', the first 150 and second 150' ring resonators being optically coupled to each other.

[0127] The first 150 and second 150' ring resonators have the shape of circles of different radii and therefore different perimeters. The perimeter of the first ring resonator 150 multiplied by the refractive index of said ring resonator 150 is a multiple plus half of the wavelength X for which an optical signal is transmitted from the waveguide 151 to the waveguide 152. The perimeter of the second ring resonator 150' multiplied by the refractive index of said ring resonator 150' is another multiple plus half of the wavelength X for which an optical signal is transmitted from the waveguide 151 to the waveguide 152. Thus, the first 150 and second 150' ring resonators transmit the optical signals of wavelength X from the first waveguide 151 to the second waveguide 152 and vice versa.

[0128] The embodiment illustrated in Figure 5B advantageously allows precise selection of the wavelengths allowing the transmission of an optical signal from the first waveguide 151 to the second waveguide 152, and vice versa.

[0129] Another embodiment having a succession of three ring resonators 150, 150' and 150” is illustrated in Figure 5C. The three ring resonators 150, 150' and 150” are identical and configured to transmit optical signals of wavelength X. This embodiment allows for even more precise selection of wavelengths for transmission from waveguide 151 to waveguide 152. Optical signals whose wavelength is not sufficiently close to X will not be transmitted by each of the ring resonators 150, 150' and 150” from waveguide 151 to waveguide 152. The portions of such optical signals not transmitted by each of the ring resonators 150, 150' and 150” are recombined together at junction 153.Since the selection of wavelengths for transmission from waveguide 151 to waveguide 152 is more precise, it is advantageously possible to expand the bandwidth of the optical signals transmitted by junction 153. The lengths of the waveguides, in which circulate said parts not transmitted by each of the ring resonators 150, 150' and 150”, are determined so that the light waves joining at junction 153 can add, regardless of their wavelength. Figure 6 illustrates a third embodiment of an optical routing system.

[0130] 11. The optical routing system 11 comprises first 16 and second 16' optical couplers and connections 20.

[0131] 7 illustrates an optical coupler 16, which comprises first 160 and second 161 waveguides. The first 160 and second 161 waveguides may be optical fibers or channel-written guides. The first 160 and second 161 waveguides are brought together over a section of length H and in which the first 160 and second 161 waveguides are separated by a distance e. The length H, the distance e and the refractive index of the medium between the first 160 and second 161 waveguides are determined so as to allow optical coupling of the first waveguide 160 with the second waveguide 161 for certain wavelengths.

[0132] In the embodiment illustrated in Figure 6, the first optical coupler 16 is configured to transmit an optical signal from the first waveguide 160 to the second waveguide 161 if the wavelength of the optical signal is X a, and, to let an optical signal pass without transmission from one waveguide to another if the wavelength of the optical signal is Xn OR X C .

[0133] The second optical coupler 16' is configured to transmit an optical signal from the first waveguide 160' to the second waveguide 161' if the wavelength of the optical signal is Xb, and to pass an optical signal without transmission from one waveguide to another if the wavelength of the optical signal is X c .

[0134] So when an optical signal is emitted by a transmitter / receiver 2 connected to the connector

[0135] 12, this will be transmitted by the first optical coupler 16, or respectively by the second optical coupler 16', towards the optical path 13a, or respectively the optical path 13b, if the wavelength of the optical signal is X a , respectively Xb. If the wavelength of the optical signal is X c, the optical signal will be directed to the optical path 13c without transmission by the first 16 and second 16' optical couplers.

[0136] Conversely, an optical signal from one of the optical paths 13a, 13b or 13c will be directed to the connection 20 connected to the connector 12 if the wavelengths of the lights are respectively X a , Xb or X c .

[0137] 8 illustrates the ratio of output power to input power of an optical signal for an optical coupler 16 according to FIG. 7 as a function of the wavelength X of the optical signal, the optical signal being transmitted from the first waveguide 160 to the second waveguide 161. As shown in FIG. 8, an optical coupler 16 is adapted for transmitting an optical signal from the first waveguide 160 to the second waveguide 161 for a plurality of different wavelengths.

[0138] An optical routing system 11 may therefore comprise a plurality of optical couplers 16 connected to each other in the form of a tree. Such an embodiment is illustrated in FIG. 9.

[0139] The optical routing system 11 illustrated in Figure 9 is configured to direct an optical signal into six different optical paths 13a-13f depending on the wavelength of the optical signal. For this, the optical routing system 11 comprises five different optical couplers 16.1-16.5 and connections 20 for optically connecting the optical couplers 16.1-16.5 to each other, and to the optical paths 13a-13f, and to the connector 12.

[0140] The optical coupler 16.1 is configured to transmit optical signals of wavelength X a, Xb, or U to the optical coupler 16.2 and to pass the optical signals of wavelength Xd, Xe, or Xf to the optical coupler 16.3. The optical coupler 16.2 is configured to transmit the optical signals of wavelength X a , or Xb to the optical coupler 16.4 and to let the optical signals of wavelength X pass c to the optical path 13c. The optical coupler 16.3 is configured to transmit the optical signals of wavelength X e , or Xf to the optical coupler 16.5 and to pass the optical signals of wavelength Xd to the optical path 13d. The optical coupler 16.4 is configured to transmit the optical signals of wavelength X ato the optical path 13a and to pass the optical signals of wavelength Xb to the optical path 13b. The optical coupler 16.5 is configured to transmit the optical signals of wavelength Xf to the optical path 13f and to pass the optical signals of wavelength Xe to the optical path 13e.

[0141] Figure 10 illustrates a fourth embodiment of an optical routing system 11. The optical routing system 11 comprises a succession of three inclined Bragg filters 17.1, 17.2 and 17.3, each configured to transmit or reflect an optical signal as a function of its wavelength. The optical routing system 11 also comprises connections 20. A lens 21 is arranged at the output of the connection 20 between the Bragg filters 17.1, 17.2 and 17.3 and the connector 12 so that when a transmitter / receiver 2 connected to the connector 12 emits an optical signal, it is transmitted to the Bragg filters 17.1, 17.2 and 17.3 in the form of a light beam F with parallel rays. The other connections 20 are each optically connected to one of the optical paths 13a-13c.

[0142] The first Bragg filter 17.1 is configured to reflect the optical signals of wavelength A to the connection 20 connected to the optical path 13a and to transmit the optical signals of wavelength ÀbOu À c .

[0143] The second Bragg filter 17.2 is configured to reflect the optical signals of wavelength A to the connection 20 connected to the optical path 13b and to transmit the optical signals of wavelength A or A-

[0144] The third Bragg filter 17.3 is configured to reflect optical signals of wavelength λ c to connection 20 connected to optical path 13c and to transmit optical signals of wavelength A or A-

[0145] Thus, an optical signal output from connector 12 will be directed to one of the optical paths 13a-13c depending on its wavelength. For example, as illustrated in Figure 10, the optical signal is of wavelength A and the second Bragg filter 17.2 reflects the light beam F to the connection 20 connected to the optical path 13b.

[0146] Conversely, according to the principle of reverse light return, an optical signal coming from one of the optical paths 13a-13c will be directed towards the connection 20 connected to the connector 12.

[0147] According to another alternative not shown here, the optical routing system 11 may comprise other optical lenses inserted between the Bragg filters 17.1-17.3 and configured to focus the beam F so as to limit its flare. Alternatively, the optical routing system 11 may comprise a first transparent medium in which the beam F is intended to circulate up to the Bragg filters 17.1-17.3 and a second transparent medium, bordering the first transparent medium and having a refractive index lower than that of the first transparent medium so as to guide the beam F in the first transparent medium while allowing the beams reflected by the Bragg filters 17.1-17.3 to pass. Figure 13 illustrates another embodiment of an optical routing system 11. The optical routing system 11 comprises a first group of switches 24.1 and a second group of switches 24.2.The first and second switch groups 24.1 and 24.2 are adapted to direct electromagnetic waves whose electric field is perpendicular to the plane in which the waveguides of the switches are inscribed, also called "trans-electric waves". Electromagnetic waves whose magnetic field is perpendicular to the plane in which the waveguides of the switches are inscribed are called "trans-magnetic waves".

[0148] The optical routing system 11 comprises a first polarizing filter 25.1 configured to steer an optical signal entering the optical routing system 11 from the connector 12 towards the first switch group 24.1, if the polarization of this optical signal is vertical, and towards the second switch group 24.2, if the polarization of this optical signal is horizontal. A first polarization rotator 26.1 is arranged between the first polarizing filter 25.1 and the second switch group 24.2. This first polarization rotator 26.1 is configured to rotate the polarization of the optical signal passing through it by 90°.

[0149] The optical routing system also comprises a second polarizing filter 25.2, a third polarizing filter 25.3 and a fourth polarizing filter 25.4. The first switch group 24.1 is configured to transmit the optical signal from the first polarizing filter 25.1 to the second polarizing filter 25.2, if its wavelength is equal to X a , to the third polarizing filter 25.3, if its wavelength is equal to Xb, and to the fourth polarizing filter 25.4, if its wavelength is equal to Xc. The second switch group 24.2 is configured to transmit the optical signal from the first polarizing filter 25.1 to the second polarizing filter 25.2, if its wavelength is equal to X a , towards the third polarizing filter 25.3, if its wavelength is equal to Xb, and towards the fourth polarizing filter 25.4, if its wavelength is equal to X c .

[0150] A second polarization rotator 26.2, a third polarization rotator 26.3, respectively a fourth polarization rotator 26.4, is arranged between the second switch group 24.2 and, respectively, the second polarizing filter 25.2, the third polarizing filter 25.3 and the fourth polarizing filter 25.4. Each of the polarization rotators 26.2, 26.3 and 26.47 is configured to change the polarization of the trans-electric optical signal into a trans-magnetic optical signal and vice versa.

[0151] The optical signals received by the second polarizing filter 25.2 from the first and second switch groups 24.1 and 24.2 are directed to the optical path 13a. Similarly, the optical signals received by the third polarizing filter 25.3 from the first and second switch groups 24.1 and 24.2 are directed to the optical path 13b. The optical signals received by the fourth polarizing filter 25.4 from the first and second switch groups 24.1 and 24.2 are directed to the optical path 13c.

[0152] Figure 11 illustrates another embodiment of an optical communication system 100 according to the invention, this comprising a plurality of optical routers 1 according to the invention and a plurality of transmitters / receivers 2.

[0153] Each of the transmitters / receivers 2 is connected to an electronic component 4, and is also optically connected to an input / output port 10 of one of the optical routers 1 via an optical fiber 3. Thus, the transmitters / receivers 2 connected to the same optical router 1 can communicate with each other, the optical router 1 distributing the optical communication signals between said transmitters / receivers 2, which allows the transmission of information between the different electronic components 4.

[0154] An input / output port 10 of an optical router 1 may also be optically connected to an input / output port 10 of another optical router 1 via an active router 5 as shown in Figure 11.

[0155] An active router 5 analyzes a received optical signal to determine the destination transmitter / receiver 2 and to transmit a new optical signal to the optical router 1 to which said transmitter / receiver 2 is optically connected, the optical signal having the appropriate wavelength for said optical router 1 to direct the optical signal to said transmitter / receiver 2.

[0156] The presence of an active router 5 in the optical communication system 100 is advantageous, since it makes it possible to reduce the quantity of different wavelengths that the transmitters / receivers 2 must emit in order to communicate with each other. For example, the optical communication system 100 comprises a first transmitter / receiver 2 connected to a first optical router 1, said first optical router

[0157] 1 being configured to direct the optical signals at a first wavelength, respectively at a second wavelength, emitted by said first transmitter / receiver

[0158] 2 to another transmitter / receiver 2 connected to the first optical router 1, respectively to an active router 5 connected to the first optical router 1. The optical communication system 100 also comprises a second optical router 1 to which a second transmitter / receiver 2 is connected, the second optical router 1 being configured to direct the optical signals at the first wavelength emitted by the active router 5 to the second transmitter / receiver 2. Thus, when the first transmitter / receiver 2 wishes to communicate with the second transmitter / receiver 2, it transmits an optical signal, containing the information of the recipient, at the second wavelength, said optical signal is directed by the first optical router 1 to the active router 5, which analyzes it and then transmits a new optical signal at the first wavelength to the second optical router 1, said optical signal then being directed by the second optical router 1 to the second transmitter / receiver 2.

[0159] The optical communication system 100 may also comprise a connection 6 connecting the relay 5 to a communication network comprising a plurality of optical communication systems 100 connected to each other.

[0160] Figure 12A illustrates another embodiment of an optical router 1 according to the invention. The optical router 1 comprises eight input / output ports 10.1-10.8 and two housings 14.1 and 14.2. The input / output ports 10.1-10.4 are fixed to the housing 14.1 and the input / output ports 10.5-10.8 are fixed to the housing 14.2. The optical signals entering one of the input / output ports 10.1-10.8 are directed according to their wavelength to another of the input / output ports 10.1-10.8 according to the previous wavelength assignment table 4.

[0161] Figure 12A illustrates the different optical paths 13a-13g optically connecting the input / output port 10.1 to each of the other input / output ports 10.2-10.8. The optical paths 13a-13c are housed in the housing 14.1. The optical paths 13d-13g exit the housing 14.1 and then enter the other housing 14.2 to optically connect the input / output port 10.1 to the input / output ports 10.5-10.8. The optical router 1 comprises a first multiplexer 18.1 and a second multiplexer 18.2 connected to the optical paths 13d-13g. The first multiplexer 18.1 is configured to concentrate all of the optical paths 13d-13g at the output of the housing 14.1 into a single waveguide 19. The second multiplexer 18.2 is configured to distribute each of the optical paths 13d-13g, then concentrated into the single waveguide 19, at the input of the other housing 14.2 to the corresponding input / output port 10.5-10.8. Thus, the optical paths 13d-13g are merged between the housing 14.1 and the other box 14.2.

[0162] Alternatively, the optical router 1 may comprise a multiplexer 18, the optical paths 13d-13g being merged between the input / output port 10.1 and the input into the housing 14.2, the multiplexer 18 being configured to separate the optical paths 13d-13g at the input of the housing 14.2 by distributing each optical path 13d-13g to the associated input / output port 10.5-10.8. This alternative is illustrated in FIG. 12B.

[0163] Figure 14 illustrates an embodiment of an optical communication system 100 suitable for quantum communication by entangled photons. The communication system 100 of Figure 14 differs from that of Figure 1 in that the transmitters / receivers 2.1 and 2.2 comprise a source 7.1 or 7.2, configured to generate at least one pair of entangled photons, a first complex absorber 8.1 or 8.2 and a second complex absorber 9.1 or 9.2 configured to measure the average polarization of the photons resulting from the amplification of the received photons. The components of each of the transmitters / receivers 2.1 and 2.2 are integrated in a housing 29.1, respectively 29.2.

[0164] In addition, the optical router used in the optical communication system illustrated in Figure 14 is a cross-type optical router, referred to as cross-type optical router 1. That is, the optical router 1 is configured to modify the polarization of the transmitted optical signal, such that the polarization of said optical signal at the output of the optical router 1 is perpendicular to the polarization of said optical signal at the input of the optical router 1. The pair of entangled photons comprises a first photon, emitted on a first propagation path 3.1 of length equal to 2L, and a second photon, emitted on a second propagation path 3.2 of length equal to L.

[0165] The first propagation path 3.1 is connected to the first complex absorber 8.1. Thus, the first complex absorber 8.1 absorbs the first photon in a polarization state chosen from the states of at least two different pairs of complementary polarization states.

[0166] The second propagation path 3.2 is connected to the input / output port 10 of the optical router 1. Thus, the optical router 1 directs the second photon to the transmitter / receiver 2.2 with which the source 7.1 and the first complex absorber 8.1 want to communicate, called the target transmitter / receiver 2.2. Said target transmitter / receiver 2.2 collects the second photon and measures its polarization. The first and second photons being entangled, the absorption of the first photon by the first complex absorber 8.1 instantly determines the polarization of the second photon.

[0167] The optical distance traveled by the second photon between the optical router 1 and the target transmitter / receiver 2.2 is equal to L. Thus, the distance traveled by the second photon is substantially the same as that traveled by the first photon. More precisely, the distance traveled by the second photon is very slightly greater than that traveled by the first photon, because the distance traveled by the second photon includes the path through the optical router 1. Subsequently, the first complex absorber 8.1 can instantaneously determine the polarization of the second photon just before it reaches the target transmitter / receiver 2.2.

[0168] Furthermore, the optical communication system 100 also comprises a polarizing filter 25.1 on the second propagation path 3.2 between the source 7.1 and the optical router 1.

[0169] The polarizing filter 25.1 makes it possible to orient an optical signal according to its polarization. In particular, the source 7.1 is configured to emit an optical signal, with entangled photons, with a first polarization which will be oriented by the polarizing filter 25.1 towards the crossed optical router 1 then directed towards another transmitter / receiver 2.2. On the other hand, the optical signals coming from the crossed optical router 1 with a second polarization perpendicular to the first polarization are oriented by the polarizing filter 25.1 towards the second complex absorber 9.1. The polarizing filter 25.1 therefore acts as a switch directing the optical signals emitted by the source 7.1 towards the optical router 1 and the optical signals received from the optical router 1 towards the second complex absorber 9.1. When a transmitter / receiver 2.1 wishes to communicate by quantum entanglement with another transmitter / receiver 2.2, the source 7.1 of said transmitter / receiver 2.1 emits entangled photon pairs at a wavelength for which the optical router 1 directs an optical signal to the other transmitter / receiver 2.2. Each entangled photon pair comprises a first photon directed to the first complex absorber 8.1 of said transmitter / receiver 2.1, and a second photon of first polarization to the polarizing filter 25.1. The polarizing filter 25.1 directs the second photon to the crossed optical router 1. The crossed optical router 1 changes the polarization of the second photon to a second polarization perpendicular to the first polarization, and then directs the second photon to another polarizing filter 25.2 arranged between the other transmitter / receiver 2.2 and the optical router 1. Since the second photon is according to the second polarization, it is then directed by the other polarizing filter 25.2 to the second complex absorber 9.2 of the other transmitter / receiver 2.2.

[0170] A first example of a crossed optical router 1 is illustrated in Figure 15. The crossed optical router 1 comprises polarization rotators 26 on each of its optical paths 13a, 13b and 13c. Each polarization rotator 26 is configured to rotate by 90° the polarization of the optical signal circulating in the corresponding optical path 13a, 13b or 13c. Thus, an optical signal with the first polarization received by the optical router 1 will be transmitted to the transmitter / receiver 2 with the second polarization. Advantageously, this simplifies the optical communication system 100 because for each transmitter / receiver 2 it is the same first polarization that can be used to transmit an optical signal from a source 7 to the optical router 1 and it is the same second polarization that can be used to receive an optical signal from the optical router 1 and orient it towards the second complex absorber 9.Polarization rotators 26 may consist of half-wave plates matched to the wavelength of the light passing through them.

[0171] Another example of a cross optical router 1 is illustrated in Figure 16. The cross optical router 1 comprises polarization rotators 28.1, 28.2 and 28.3 in each of the input / output ports 10.1, 10.2 and 10.3, between the corresponding connector 12.1, 12.2 or 12.3 and the corresponding optical routing system 11.1, 11.2 and 11.3. Each polarization rotator 28.1, 28.2 and 28.3 is configured to rotate the polarization of the optical signal transmitted through said polarization rotator 28.1, 28.2 or 28.3 by 45°. Thus, an optical signal with the first polarization received by the optical router 1 will be transmitted to the transmitter / receiver 2 with the second polarization.Advantageously, this simplifies the optical communication system 100 because for each transmitter / receiver 2 it is the same first polarization which can be used to transmit an optical signal from a source 7 to the optical router 1 and it is the same second polarization which can be used to receive an optical signal from the optical router 1 and direct it towards the second complex absorber 9.

[0172] Figure 17 illustrates a preferred variant of the crossed optical router 1. In said crossed optical router 1, each of the optical routing systems 11.1, 11.2 and 11.3 comprises a first switch group 24.1 and a second switch group 24.2. The first and second switch groups 24.1 and 24.2 are adapted to direct electromagnetic waves whose electric field is perpendicular to the plane in which the waveguides of the switches are inscribed, also called "trans-electric waves". Electromagnetic waves whose magnetic field is perpendicular to the plane in which the waveguides of the switches are inscribed are called "trans-magnetic waves".

[0173] Each of said optical routing systems 11.1, 11.2 and 11.3 comprises a polarizing filter 25 configured to steer an optical signal entering the optical routing system 11.1, 11.2 or 11.3 from the connector 12.1, 12.2 or 12.3 towards the first switch group 24.1, if the polarization of this optical signal is vertical, and towards the second switch group 24.2, if the polarization of this optical signal is horizontal. For each of said optical routing systems 11.1, 11.2 and 11.3, a polarization rotator 26 is arranged between the polarizing filter 25 and the second switch group 24.2. This polarization rotator 26 is configured to rotate the polarization of the optical signal passing through it by 90°.

[0174] For each optical routing system 11.1, 11.2 and 11.3, the optical paths 13a, 13b and 13c at the output of the first switch group 24.1 are connected to the second switch groups 24.2 of the other optical routing systems 11.1, 11.2 or 11.3. Similarly, for each optical routing system 11.1, 11.2 and 11.3, the optical paths 13a, 13b and 13c at the output of the second switch group 24.2 are connected to the first switch groups 24.1 of the other optical routing systems 11.1, 11.2 or 11.3. Thus, when the input / output port 10.1 receives a vertically polarized optical signal through its connector 12.1, this optical signal is directed to the first switch group 24.1 by the polarizing filter 25. The first switch group 24.1 directs the optical signal to the second switch group 24.2 of the optical routing system 11.2 if the optical signal is of wavelength a, or to the second switch group 24.2 of the optical routing system 11.3 if the optical signal is of wavelength b. After passing through the corresponding second switch group 24.2, the optical signal passes through the polarization rotator 26 of the optical routing system 11.2 or 11.3. The polarization of the optical signal is then rotated by 90° and becomes horizontal. The optical signal is then directed out of the optical router 1 through the polarizing filter 25 of the optical routing system 11.2 or 11.3 and then through the connector 12.2 or 12.3.

[0175] Similarly, when the input / output port 10.1 receives a horizontally polarized optical signal through its connector 12.1, this optical signal is directed by the polarizing filter 25 of the optical routing system 11.1 to the polarization rotator 26 of the optical routing system 11.1. The polarization of the optical signal is then rotated by 90° and becomes vertical. The optical signal is then directed to the second switch group 24.2 of the optical routing system 11.1. The second switch group 24.2 directs the optical signal to the first switch group 24.1 of the optical routing system 11.2 if the optical signal is of wavelength X a, or to the first switch group 24.1 of the optical routing system 11.3 if the optical signal is of wavelength Xb. After passing through the corresponding first switch group 24.1, the optical signal is directed out of the optical router 1 through the polarizing filter 25 of the optical routing system 11.2 or 11.3 and then through the connector 12.2 or 12.3.

[0176] As illustrated in Figure 14, the optical communication system 100 may also comprise two polarizing devices 27.1 and 27 or 27.2 and 27 on each second propagation path 3.2 between the corresponding polarizing filter 25.1, respectively 25.2, and the optical routing system 11 of the optical router 1. One of the two polarizing devices 27.1 or 27.2 is arranged just after the polarizing filter 25.1, respectively 25.2, with respect to the transmitter / receiver 2.1, respectively 2.2, and the other of the polarizing devices 27 may be arranged just before the input / output port 10 of the optical router 1. Alternatively, said other polarizing device 27 may be integrated into the input / output port 10 and / or into the housing 30 of the optical router 1, said other polarizing device 27 being arranged just before the optical routing system 11. The polarizing devices 27.1 or 27.2 can be housed in the housings 29.1, respectively 29.2, of the transmitter / receiver 2.1, respectively 2.2. Each polarizing device 27.1, 27.2 and 27 is configured to transform a linearly polarized optical signal into a circularly polarized optical signal. Thus, the optical signals circulating between the polarizing device 27.1, or 27.2, and the polarizing devices 27 are circularly polarized.

[0177] 18 illustrates a polarizing device 27 for the optical communication system 100 of FIG. 14. Since the polarizing device 27 must operate for a plurality of wavelengths, it comprises two multiplexers 271, one at the input and the other at the output, in order to distribute the received optical signals into different optical paths 272a, 272b or 272c according to their wavelength. For example, the multiplexers 271 are configured to transmit in the optical path 272a the optical signals of wavelengths a, in the optical path 272b the optical signals of wavelengths b, and in the optical path 272c the optical signals of wavelengths A c . The polarizing device 27 comprises on each of its optical paths 272a, 272b and 272c a quarter-wave plate 273a, 273b, respectively 273c. The quarter-wave plate 273a is configured to transform an optical signal of wavelength A a and linearly polarized into an optical signal of wavelength λ a and circularly polarized. The quarter-wave plate 273b is configured to transform an optical signal of wavelength λn and linearly polarized into an optical signal of wavelength λn and circularly polarized. The quarter-wave plate 273c is configured to transform an optical signal of wavelength λn c and linearly polarized into an optical signal of wavelength λ c and circularly polarized.

[0178] Other variations and improvements may be envisaged without departing from the scope of the invention as defined by the claims below.

[0179] In particular, it is possible to combine the different embodiments of the optical routing systems 11 with each other. For example, an optical routing system 11 may comprise a prism 14 or a Bragg filter 17 and a plurality of resonator couplers 15 and / or a plurality of optical couplers 16, the prism 14 or the Bragg filter 17 being configured to transmit optical signals of wavelengths shorter than a predetermined length to a first group of resonator couplers 15 or optical couplers 16 and to transmit optical signals of wavelengths longer than the predetermined length to a second group of resonator couplers 15 or optical couplers 16.

Claims

Claims 1. Optical router (1) for distributing optical signals, comprising at least three input / output ports (10), each adapted to be optically connected to a transmitter / receiver (2) configured to transmit and receive optical signals according to a plurality of different wavelengths, each input / output port comprising an optical routing system (11) connected to a plurality of optical paths (13), internal to the optical router, each of the optical paths also being connected to another of the optical routing systems so as to optically connect the input / output port to each of the other input / output ports, the optical routing system being configured to passively direct an optical signal received by the input / output port into one of the optical paths chosen as a function of the wavelength of said optical signal,the optical path through which an optical signal of a given wavelength is directed from a first input / output port to a second input / output port being the same optical path as that taken by an optical signal of the given wavelength from the second input / output port to the first input / output port., 2. Optical router according to the preceding claim, at least one, preferably each, of the optical routing systems comprising one or more switches for directing an optical signal according to its wavelength, each switch being chosen from: a prism (14) made of transparent dispersive material, - a resonator coupler (15) comprising first (151) and second (152) waveguides and at least one ring resonator (150) arranged between the first and second waveguides, the ring resonator being configured to transmit an optical signal from the first waveguide to the second waveguide, and vice versa, depending on the wavelength of the optical signal, - an optical coupler (16) comprising two waveguides (160, 161) comprising a section in which the two waveguides are brought closer to each other so as to transmit an optical signal from one of the waveguides to the other of the waveguides as a function of the wavelength of the optical signal, - a Bragg filter (17) inclined and configured to transmit or reflect an optical signal depending on its wavelength, - a Bragg grating.

3. Optical router according to the preceding claim, the waveguides of the switches being optical fibers or channel guides, preferably the channel having a rectangular base, preferably square, with a side between 0.020 pm and 5 pm for example, preferably between 0.15 pm and 5 pm.

4. Optical router according to claim 2 or 3, at least one of the input / output ports comprising a connector (12) to which a transmitter / receiver is intended to be connected, the connector being configured to optically connect a transmitter / receiver, possibly extended by an optical fiber or a channel guide, to the optical routing system of said input / output port.

5. Optical router according to one of claims 2 to 4, at least one of the optical routing systems comprising connections (20) configured to optically connect the switches to each other and / or to optically connect the switches with the connector.

6. Optical router according to the preceding claim, the connections being optical fibers or channel guides, preferably the channel having a rectangular base, preferably square, with a side between 0.020 pm and 5 pm for example, preferably between 0.15 pm and 5 pm.

7. Optical router according to one of the preceding claims, the optical routing systems being configured to passively direct optical signals with a wavelength between 169 nm and 14 pm.

8. Optical router according to one of the preceding claims, the optical paths comprising one or more waveguides (13) in which the optical signals are intended to circulate, preferably the waveguides being optical fibers or channel guides, preferably the channel having a rectangular base, preferably square, with a side length between 0.020 pm and 5 pm for example, preferably between 0.15 pm and 5 pm.

9. Optical router according to one of the preceding claims, each of the optical routing systems comprises first and second groups of switches (24.1, 24.2) configured to passively direct an optical signal, emitted by the transmitter / receiver connected to the input / output port, to the same other input / output port chosen according to the wavelength of said optical signal, said optical routing system comprising a polarizing filter (25, 25.1) arranged upstream of all the switches, said polarizing filter being configured to orient said optical signal towards the first group of switches if said optical signal is according to a first polarization, for example vertical, or towards the second group of switches if said optical signal is according to a second polarization perpendicular to the first polarization, for example horizontal, said optical routing system comprising a polarization rotator (26, 26.1) configured to rotate 90° the polarization of the optical signal arranged between the polarizing filter and the second switch group.

10. Optical router according to the preceding claim, the optical paths at the output of the first group of switches, respectively of the second group of switches, of an optical routing system are connected to the second groups of switches, respectively to the first groups of switches, of the other optical routing systems.

11. Optical communication system (100) comprising at least one optical router (1) according to one of the preceding claims and, for each optical router, a plurality of transmitters / receivers (2) configured to transmit and receive optical signals according to a plurality of different wavelengths, each of the transmitters / receivers being connected to one of the input / output ports of the optical router.

12. System according to the preceding claim, at least one, preferably each, of the transmitters / receivers being configured to transmit and receive optical signals according to a plurality of different wavelengths at least equal to Nl, N being equal to the number of input / output ports of the optical router to which the transmitter / receiver is connected.

13. System according to claim 11 or 12, at least one of the transmitters / receivers comprising a plurality of lasers, each laser being configured to emit an optical laser signal of a wavelength different from the other lasers.

14. Optical communication method comprising the use of an optical communication system (100) according to one of claims 11 to 13, the use comprising the transmission of an optical signal by one of the transmitters / receivers (2), called the first transmitter / receiver, and the reception of the optical signal by at least one other of the transmitters / receivers, called the second transmitter / receiver.

15. Method according to the preceding claim, the first and second transmitters / receivers being connected with a first electronic component (4), respectively a second electronic component (4), the use comprising the communication of information from the first electronic component to the second electronic component by the emission of an optical signal from the first transmitter / receiver and the reception of said optical signal by the second transmitter / receiver, preferably the first and second electronic components being processors and / or memory blocks and / or network peripherals and / or computer peripherals.

16. Method according to claim 14 or 15, the use comprising a calibration step during which at least one of the transmitters / receivers, called the transmitter / receiver to be calibrated, sends at least one optical signal at a given wavelength, then the optical signal is received by another of the transmitters / receivers which sends in return an optical response signal indicating its identity at the same said given wavelength, and the transmitter / receiver to be calibrated then records the identity of the other transmitter / receiver and associates it with the given wavelength.

17. Method according to the preceding claim, the optical signal emitted by the transmitter / receiver to be calibrated indicates the identity of said transmitter / receiver and the other transmitter / receiver records the identity of the transmitter / receiver to be calibrated and associates it with the given wavelength.

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