Apparatus and method for free space optical signals

Abstract

An apparatus (100) configured to transmit and receive free space optical signals. The apparatus comprises a plurality of optical lenses (102) configured to transmit first optical signals, and receive at least one second optical signal. The plurality of optical lenses (102) are spaced apart on the apparatus. An optical lens system (106) is configured to align the first optical signals. Each of the plurality of the optical lenses (102) is configured to transmit a said first optical signal with a different wavelength than the other of the plurality of the optical lenses (102).

Description

[0001] APPARATUS AND METHOD FOR FREE SPACE OPTICAL SIGNALS

[0002] Technical Field

[0003] Embodiments of the present disclosure relate to an apparatus and method, the apparatus and method using free space optics to transmit and receive an optical signal. In some examples, the apparatus also transmits and receives microwave frequency signals.

[0004] Background

[0005] Microwave links are a known technology, which can provide, for example, up to 10Gb / s on short to medium distances. Microwave links are generally implemented in licensed frequency bands and can be impacted by antenna misalignment and weather conditions.

[0006] Free Space Optics (FSO) is a relatively new technology being introduced in the telecommunication environment to provide higher capacity for generally unlicensed bands (e.g., in the infrared part of the optical spectrum), where a line of sight is available between the two end points of the FSO link.

[0007] FSO is a promising technology to support future transport infrastructure, for example in 6G. This is due to the very large capacity in the unlicensed infrared spectrum. FSO may be impacted by obstacles on the line of sight and by weather conditions, though it is expected to be differently impacted with respect to microwave links, e.g. in respect of weather conditions.

[0008] Further, FSO is expected to use reduced power with respect to microwave links in short distance connections, so may be preferred in good line of sight conditions to a microwave link in order to reduce power consumption. In some cases, a microwave link can be activated in case weather or environmental conditions do not allow FSO transmission.

[0009] Radio Access Network, RAN, operators using both microwave and FSO to connect two sites need to install, align and manage the two different systems separately and then switch their traffic into the two systems. The installation of two systems may cause increased costs in terms of footprint, installation, and alignment of the transmitters and receivers to achieve a line of sight.

[0010] Summary

[0011] An aspect of the disclosure provides an apparatus configured to transmit and receive free space optical signals. The apparatus comprises a plurality of optical lenses configured to transmit first optical signals, and receive at least one second optical signal, wherein the plurality of optical lenses are spaced apart on the apparatus. The apparatus further comprises an optical lens system configured to align the first optical signals. Each of the plurality of the optical lenses is configured to transmit a said first optical signal with a different wavelength than the other of the plurality of the optical lenses.

[0012] A furher aspect of the disclosure provides a method of transmitting free space optical signals. The method comprises transmitting first optical signals from a plurality of optical lenses to an optical lens system, wherein the plurality of optical lenses are spaced apart on the apparatus, and each wavelength is transmitted by only one of the optical lenses. The method further comprises aligning and transmitting the first optical signals by the optical lens system.

[0013] Brief Description of Drawings

[0014] For a better understanding of the present disclosure, and to show how it may be put into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0015] Figure 1 is a view of the apparatus;

[0016] Figure 2 is a schematic view of part of the FSO parts of the apparatus;

[0017] Figure 3 is a schematic view of part of the FSO and microwave parts of the apparatus;

[0018] Figure 4 is a schematic view of part of the FSO and microwave parts of the apparatus;

[0019] Figures 5a and 5b are schematic views of part of the FSO and microwave parts of the apparatus;

[0020] Figure 6 is a method according to a first example of the disclosure using the apparatus;

[0021] Figure 7 is a method according to a second example of the disclosure using the apparatus; and

[0022] Figure 8 is a method according to a third example of the disclosure using the apparatus.

[0023] Detailed Description

[0024] For the purpose of explanation, details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed. It will be apparent, however, to those skilled in the art that the embodiments may be implemented without these specific details or with an equivalent arrangement.

[0025] The present disclosure exploits the commonalities and the differences between microwave and FSO propagation in the line-of-sight systems, in order to augment one or more of the resiliency of the link, complexity of installation, power supply and maintenance of the outdoor site.

[0026] Figure 1 shows an apparatus 100 configured to transmit and receive free space optical, FSO, signals. In some examples, the apparatus 100 is further configured to transmit and receive microwave frequency signals. As such, the apparatus 100 provides a single, integrated, apparatus for both a FSO and microwave communication link between two nodes. For example, the two nodes are nodes in a radio access network node, e.g. nodes comprising a baseband unit and a radio unit, or as a backhaul link between a base station and the core network. The apparatus 100 may be considered as communications apparatus or a transport apparatus.

[0027] The apparatus 100 comprises a plurality of optical lenses 102 configured to transmit first optical signals. In some examples, the first optical signals comprise a plurality of signals, which may or may not comprise different data signals. The optical lenses 102 are further configured to receive an at least one second optical signal. The plurality of lenses 102 are spaced apart on the apparatus 100. The first optical signals comprise a plurality of different wavelengths, e.g. as a wavelength division multiplexed signal. The lenses may alternatively be referred to as micro-lenses.

[0028] In some examples, the apparatus 100 further comprises a microwave apparatus configured to provide a microwave link to transmit and receive microwave frequency signals. The microwave apparatus comprises a dish 104 coupled to a microwave feeder 110.

[0029] In some examples, the lenses 102 are located on the dish 104, for example, spaced apart on the microwave dish 104 configured for use in the microwave link. For example, the lenses 102 are arranged at or adjacent to a periphery of the dish. In some examples, the lenses are equally spaced adjacent to the circular periphery of the dish 104. In some examples, the dish has a substantially circular periphery; other shapes of dish may be used. In some examples, the dish is concave, and the microwave feeder 110 is at a focus point of the dish.

[0030] The apparatus 100 further comprises an optical lens system 106. The optical lens system 106 is configured to align a transmission direction of the transmitted at least one first optical signals. The optical lens system 106 comprises one or more optical lenses configured to provide an optical path from the plurality of optical lenses 102 to the transmission direction to the other node. In some examples, the optical lens system 106 is configured to change the transmission or reception direction to connect the separate optical lenses 102 with the transmission direction. In some aspects, the optical lens system 106 is configured to collimate, or align, light from the lenses 102. The optical lens system 106 is configured to collimate, or align, first optical signals for transmission from the plurality of spaced apart lenses 102 into a single transmission direction towards the remote node. In some examples, the optical lens system 106 is configured such that optical signals received from a different transmission direction are not transmitted on to the optical lenses 102. In some examples, the optical lens system 106 provides for a selection of optical signals based on the reception direction. The optical lenses 102 are configured to transmit a first optical signal to the optical lens system 106, for collimation with the other first optical signals. In some aspects, the lenses 102 are configured to direct the optical first signal in a narrow beam directly to the optical lens system 106.

[0031] The optical lens system 106 is attached to a support 112, configured to position the optical lens system 106 at the correct position in relation to the lenses 102.

[0032] The microwave feeder 110 is attached to a support 112, configured to position the microwave feeder 110 at the correct position in relation to the dish 104. In some examples, the optical lens system 106 and microwave feeder 110 are attached to the same support 112. The optical lens system 106 is attached on an exterior side of the support 112, relative to the microwave feeder 110. In other words, the microwave feeder 110 is located between the optical lens system 106 and the dish 104. This allows the optical signals to be transmitted and received without interference by the microwave feeder 110. For example, the optical lens system 106 diverts the optical signals past the location of the microwave feeder 110. The optical lens system 106 is substantially transparent to the microwave signals.

[0033] In some aspects, the apparatus 100 provides for the usage of the microwave antenna dish 104 to position multiple FSO sources. The FSO sources are converging on an optical lens system 106, e.g. a bi-convex lens, positioned after the microwave feeder in its shadow cone (so not to interfere with the microwave beam).

[0034] The distance between the lenses 102, and / or, the optical lens system 106 and the FSO sources (lenses 102), as well as the convergence angle, allows to increase the selectivity of the FSO antenna to make it equivalent to a bigger lens. The principle is that the larger the distances between the lenses 102 and the convergence angle to the optical lens system 106, the higher the selectivity. The selectivity is a measure of the ability of the apparatus to select received optical signals from a particular direction, and not receive optical signals from other directions. Thus, having physically separated (spaced apart) lenses 102 for receiving the optical signal provides for an improved reception on the FSO link. The same principle is used in microwave antennas to have tighter lobes towards the remote antenna site.

[0035] For transmission using the plurality of spaced apart lenses, this solution overcomes the recognized challenge due to the multipath propagation of the same light signal from the different light sources to the convergence lens and eventually to the remote antenna. In this regard, each of the plurality of the optical lenses 102 is configured to transmit a said first optical signal with a different wavelength than transmitted by the other of the plurality of the optical lenses 102. In some examples, each lens 102 is used to transmit only one wavelength, or lambda. The single wavelength transmitted is different to the wavelengths transmitted by the other lenses 102. In other examples, one or more lenses 102 may be used to transmit a plurality of wavelengths or lambdas. However, each wavelength for transmission is transmitted by only one of the plurality of lenses. This avoids interferometic interference of the first optical signals at the optical lens system 106.

[0036] The optical lenses 102 are connected to optical circuitry 108. The optical circuitry 108 is configured to provide one or more first optical signals to the lenses 102. In some examples, the optical circuitry 108 is configured to generate and / or transmit a single wavelength to a particular lens 102. In some examples, the optical circuitry 108 is connected to the lenses 102 by optical fibers 111 , e.g. a separate optical fiber 111 per lens 102. The optical fibers are optically connected to the lenses 102 such that an optical signal for transmission is transmitted through the optical fiber 111 and from the attached lens 102. In receiving, light received at the lens 102 is directed into the optical fiber for transmission to the optical circuity for receiving the signal.

[0037] In some examples, the optical circuitry 108 comprises one or more laser to generate the one or more optical wavelengths for transmission. In other examples, the optical circuitry 108 comprises one or more filter or other optical equipment for filtering or optically processing the wavelengths for transmission or receiving of the received optical signals. The optical circuitry 108 may alternatively be referred to by its components, e.g. transmitters, laser sources, filters, receivers, photodiode, or as an optical modem, FSO modem, optical transceivers, optical module or optical source.

[0038] In some examples, the optical circuitry 108 comprises one or more modulators to modulate an optical wavelength. For example, the modulators may be Mach- Zender modulators. Controlled phase variations are used in the Mach-Zender modulators, in which two optical copies are modulated in-phase or in-quadrature to transmit 0 and 1 bits of data.

[0039] The plurality of lenses 102 are configured to transmit the first optical signals with different optical wavelengths provided by the optical circuitry 108. The lenses 102 utilize separate optical wavelengths, which may also be referred to as optical frequencies. The optical wavelengths include infrared wavelengths, as well as, for examples, wavelengths in a visible part of the spectrum.

[0040] The transmission of different wavelengths by each of the operating lenses 102 (each wavelength is transmitted by only one lens) avoids the possibility of interferometric interference from transmitting the same wavelength from multiple lenses 102. The light source distance (e.g. the distance from the laser source in the optical circuitry to the optical lens system 106) can be subject to variations due to mechanical vibrations (e.g., due to wind conditions) and it may be difficult to implement exactly the same fiber path from the laser, e.g. in the optical circuitry 108 to each of the lenses 102 on the dish. It is noted the FSO lambdas are in the order of micrometers and even a small difference can create out-of-phase components. The apparatus 100 uses different lambda for each of the light paths, to overcome the problem of interferometric interference from light propagation of the same spectrum over multiple paths.

[0041] The apparatus 100 is configured to transmit the first optical signals in the same direction as the microwave frequency signals. The transmission direction of the optical link and microwave link are aligned. In some examples, this allows for alignment to be carried out for only one of the optical link and microwave link with the other, remote, node. An alignment process for the other of the optical link and microwave link is not then required. Alternatively, separate alignment processes may be carried out for each of the optical link and microwave link.

[0042] In some examples, the apparatus 100 is configured to transmit the same data on the first optical signal from a plurality of the optical lenses 102. As such, the same data is transmitted on different wavelengths. For example, all of the optical lenses 102 transmit the same data on the first optical signal. In some examples, one or more optical lenses are used to transmit different data on the first optical signal from at least one of, or each, of the other optical lenses. The data on the first optical signal may be the same as, or different to, a signal sent on the microwave link. In some examples, the optical link operates at the same time as the microwave link. Alternatively, only one of the optical link and microwave link operate at the same time.

[0043] The apparatus 100 provides a solution utilizing FSO and microwave communication in the same site on the same antenna dish. Integration of the FSO optics within the microwave antenna dish (optical lenses 102 and a collimator 106) avoids any interference with the microwave signal in front of the antenna dish.

[0044] In some examples, the optical circuitry 108 comprises a passive optical filter to multiplex / demultiplex (Mux / DeMux) the FSO signal into wavelength division multiplexed (WDM) subchannels. In some examples, the same laser source is split over multiple channels by using a WDM passive filter. This allows each lens 102 on the antenna dish to transmit and receive only a single lambda. On the receive side, each lambda is converted electronically with a photodiode, avoiding any recombination of out-of-phase components. In some examples, the at least one photodiode for receiving is in the optical circuitry 108. In some examples, the received wavelengths of the received second optical signal may be received at the optical lens system 106, which directs the wavelengths to the lenses 102. The received optical signal may comprise a plurality of wavelengths, e.g. as a WDM second optical signal. The received optical signal may received via any of the lenses, i.e. each of the plurality of lens is used to pass all received wavelengths to the receiver (e.g. the optical circuitry 108). Alternatively, each lens 102 is associated with a only a subset of the wavelengths, e.g. one wavelength. A received wavelength is passed to the optical circuitry only via a specific lens corresponding to that wavelength.

[0045] It is noted that refraction index of air is very close to 1 , therefore null or minimal chromatic dispersion is expected for the links considered (e.g., up to 1 km).

[0046] The apparatus is configured to be a mechanical and fiber solution implemented to avoid placing any active FSO component in front of the antenna dish 104. The apparatus 100 comprises a hybrid microwave and optical feeder used to share the same direction of the antenna dish to ensure the common alignment of the FSO and microwave beams. Lenses 102 are placed in the antenna dish, pointing to the FSO feeder (e.g. optical lens system 106) and connected to optical fibers 111 placed behind the dish

[0047] It is possible to compare the performance of the links in order to check the full alignment of the antennas. For example, detecting a lower performance than a threshold may be detected by a feedback loop, which may indicate that there is a sub-optimal alignment to or from the remote node. The more precise alignment required for the FSO system, allows for detection of the alignment for the microwave system. In some examples, a motorized alignment system is used, based on the FSO feedback.

[0048] The disclosure includes an apparatus and method to operate a combined FSO and microwave system, in which a FSO collimator system is integrated within a microwave antenna by means of micro-lenses connected to WDM passive filters. The usage of WDM allows the use of multiple FSO sources with a reduced risk of interferometric coherence due to multipath propagation. The lenses are located on or adjacent to the external circumference of the microwave antenna in order to mitigate any degradation of the microwave antenna performances and / or improve FSO receiving performance.

[0049] In some aspects, a plurality of lens carries a WDM subchannel of the FSO signal and collimates it to the FSO feeder, e.g. the optical lens system, placed just after the MW feeder. In some examples, the FSO feeder is made of glass, so a dielectric for the microwave signal and located in the shadow of the microwave feeder, thus not affecting MW beam propagation. The optical lens system 106 is configured to transmit and receive collimated light signals, connecting the remote node with the lenses 102 on the microwave dish.

[0050] Figure 2 shows a schematic view of the optical lens system 106 in association with the dish 104 comprising lenses 102. The view in Figure 2 is not to scale. In some examples, the optical lens system 106, also known as the FSO feeder, comprises a concave lens 117 and a convex lens 118. The optical lens system 106 is configured to collect the signals from the FSO lenses 102 on the dish and collimate the optical signals as a single FSO beam fully aligned with the microwave beam. This is shown by the parallel lines to the right of the convex lens 118. The optical lens system 106 provides a single transmission direction for all of the first optical signals from the spaced apart lenses 102. The optical lens system 106 also functions to receive a collimated signal from the remote node, and pass the receive collimated signal to the plurality of lenses 102.

[0051] In some examples of optical lens system 106, the convex 118 lens has a focal point which is aligned with the concave lens 117. The relative positioning of the lenses 117,118 is such that the light beams are rectified on the front plate of the antenna. A corresponding functionality applies for transmitted and received signals. Any deviating beam is diverted outside of lenses or collimated beam direction, e.g. a received beam from a different direction is not passed to the lenses 102. This provides for a selectivity of the FSO system, and an improved selectivity with respect to a single lens. Any received laser beam not orthogonal to the front convex lens will be diverted away from the lenses 102, significantly reducing the interference and noise from other light sources.

[0052] Using this optical lens system 106, or another arrangement of lenses, any signal incoming from the antenna dish 102 is converged towards the same front direction of transmission, and any incoming signal orthogonal to the lens is sent to the antenna dish receivers, e.g. lenses 102. The usage of WDM allows the use of multiple FSO sources without risk of interferometric coherence due to multipath propagation. The location of the lenses at or adjacent to the external circumference of the microwave antenna in order mitigates degradation of the microwave antenna performances. The FSO and microwave technologies operate in completely different parts of the electromagnetic spectrum, for example FSO may operate in the infrared region around 140 THz, and the microwave system may operate in any one or more parts of the 1-60 GHz region. As such, the two technologies, can be affected differently by the environmental conditions. By combining their characteristics in the same antenna system, it may be possible to increase the resilience of the combined link.

[0053] Figure 3 shows the apparatus 100, including the microwave system comprising the dish 104 and microwave feeder 110. The focus of the microwave dish and the optical FSO system are slightly displaced over the same orthogonal axis in order to focus on the microwave feeder 110 and the FSO feeder (optical lens system 106) respectively. As shown, the microwave feeder 110 is closer to the dish than the FSO feeder. Alternatively, the FSO feeder may be considered as on an exterior side of the microwave feeder 110 or closer to the remote node. The microwave feeder 110 is connected to a microwave transceiver or comprises a microwave transceiver.

[0054] Figure 4 shows the apparatus 100 comprising optical circuitry 108, comprising a FSO modem 120. The apparatus 100 further comprises a microwave modem 122. The FSO modem 120 is configured to convert a data signal into an optical signal to be transmitted. The microwave modem 122 is configured to convert a data signal into a microwave signal to be transmitted. In some examples, the FSO modem 120 comprises a plurality of lasers or laser ports 124, each providing a single wavelength different to the wavelengths of the other lasers. The optical circuitry further comprises a modulator which can modulate the laser to carry the data signal. The lasers or laser ports are separately connected to the lenses, e.g. one wavelength per lens, by optical fibers 111.

[0055] Figure 4 shows that optical fiber cables 111 are connected and stitched to the back of the microwave antenna dish. In some examples, optical circuitry, e.g. a WDM passive filter, can be integrated in the microwave modem enclosure. For example, the WDM passive filter is a completely passive component, not requiring a power supply. In some examples, the WDM passive filter is tolerant to environmental temperature.

[0056] The optical circuitry comprising the FSO electronics (e.g. laser and EDFA amplifiers) are arranged behind the antenna dish, for example, in an indoor cabinet or outdoor enclosure and connected via optical fibers 111 to the hybrid antenna. FSO and microwave signals can be either controlled by separate modems to be switched at Ethernet level or alternatively controlled by a common microwave and FSO Modem System to leverage synergies, power saving and resiliency between the two technologies. In one example, a hybrid microwave and FSO Modem is used in order to proactively adapt the microwave and FSO modulations to the link conditions and / or optimize energy saving between the MW and the IR bands.

[0057] An advantage of the disclosed solution is a reduced footprint of microwave and FSO systems, and simplifying the installation practice. Using this apparatus and method, it is possible to deploy the FSO system without the need for extra space on a support pole 140 and without the need for additional licenses.

[0058] The apparatus and method provides for an increase in the reliability and availability of the wireless microwave link, due to the different propagation impairments that can impact FSO and microwave signals, which potentially do not occur at the same time.

[0059] In some examples, the apparatus 100 is configured to transmit the signal over the FSO and microwave links to provide 1 + 1 protection at the destination. Alternatively, the FSO and microwave link may use a 2+0 scheme to increase the bandwidth transmitted over the links during perfect conditions. For example, the microwave and FSO links are used simultaneously to transmit separate parts of data. In some examples, the apparatus 100 is configured to fallback to one technology (i.e. one of the FSO link or microwave link) in case of temporary propagation issues, e.g. due to weather conditions such as rain or fog.

[0060] The use of WDM optics allows the use of multiple lenses, connected to transceivers, which are spaced apart on the apparatus. The use of multiple lenses, spaced apart, provides for improved reception of FSO optical signals. The use of separate wavelengths being transmitted from each lens avoids issues with interferometry due to different fiber lengths (e.g. if the same wavelength were transmitted by a plurality of lenses) and environmental conditions. This use of WDM simplifies the FSO system supply and its installation; since the apparatus 100 increases the FSO system’s tolerance to installation errors. The apparatus 100 uses passive components in front of the microwave antenna, e.g. the optical lens system 106. The FSO system does not create any interference with the microwave system and can leverage on the alignment control of the microwave system.

[0061] In some examples, the overall link capacity can be modulated between microwave and FSO (e.g. in IR bands) with a common modem. In some examples, the FSO link is used during perfect line-of-sight conditions, for example in order to save the power required by the microwave link. In some examples, the transmitted first optical signals and received second optical signals are differentiated from each other at an optical level. For example, the transmitted first optical signals and received second optical may use a different light polarization or WDM multiplexing, for example, using different wavelengths for transmitting and receiving.

[0062] Examples of the present solution may be used in association with any type of radio technology, e.g. 5G or 6G. The apparatus 100 represents an alternative to off-the- shelf FSO solutions that require a dedicated installation and continuous alignment. Thus, the use of the present disclosure provides for a reduced installation and maintenance costs. FSO systems provide for a high-capacity wireless connection, e.g. higher than a microwave link.

[0063] Figures 5a and 5b show the the apparatus 100 including the client 130 providing the data for transmission or for receiving data. The client may be any telecommunications equipment or data processor, for example, in a radio access network. The system includes the client and the modem components for the FSO and microwave links. Figures 5a and 5b show the fibers 111 for carrying the wavelengths to / from the lenses 102, the microwave model is also connected (not shown) to the microwave feeder 110, as described above.

[0064] In Figure 5a, the apparatus 100 is configured to transmit additional data using the integrated FSO and microwave link, which may also be referred to as extra-traffic, by utilizing both the FSO and microwave links in the same direction. As such, the data from the client is split between the FSO modem and microwave modem for separate transmission. On reception, the client may receive independent data from both the FSO modem and the microwave modem. In Figure 5b, if one of the FSO link and microwave link are not available, the data can be transmitted over the other link. Thus, the apparatus 100 provides for increased reliability. Alternatively, the FSO modem and microwave modem can be used at the same time to carry the same data for protection purposes.

[0065] In some examples, one or more of the optical wavelengths transmit the same data. This provides for a redundancy in the transmission, improving reliability. In some examples, all wavelengths are modulated with the same data. In a further example, one or more of the WDM channels carry independent signals, e.g. different or separate data. In some examples, all of the WDM channels, i.e. optical wavelengths, carry different data. The data carried at the same time by the separate optical wavelengths may be aggregated at the receiver FSO Modem. The use of different wavelengths to carry separate data provides for a higher capacity. In some aspects, this requires more stringent environmental conditions as there is not a WDM multipath propagation which would provide for redundancy in the data transmission.

[0066] Figure 6 shows an example method 200 of transmitting data using the apparatus.

[0067] In 206, a plurality of optical lenses transmit first optical signals. The plurality of optical lenses 102 are spaced apart on the apparatus, e.g. on the dish 104. The first optical signals comprise a plurality of wavelengths. Each wavelength is transmitted by only one of the optical lenses 102.

[0068] In 208, the first optical signals are aligned and transmitted by the optical lens system 106.

[0069] Figure 7 shows an example method 220 of transmitting data using the apparatus.

[0070] In 222, a plurality of first optical signals is generated, e.g. by one or more lasers. The plurality of first optical signals comprise different wavelengths, such that the first optical signal is a WDM signal. The first optical signals are modulated with data for transmission.

[0071] In 224, the different wavelengths are transmitted a plurality of optical lenses 102 are spaced apart on the apparatus, e.g. on the dish 104. In 226, the plurality of optical lenses transmit the first optical signals. Each wavelength of the first optical signal is transmitted by only one of the optical lenses 102.

[0072] In 228, the first optical signals are aligned and transmitted by the optical lens system 106.

[0073] Figure 8 shows an example method 240 of receiving data using the apparatus.

[0074] In 242, second optical signals are receiving by the optical lens system 106.

[0075] In 244, the optical lens system 106 transmits the second optical signals to the plurality of lenses 102.

[0076] In 246, the plurality of lenses 102 transmit the second optical signals to the optical circuitry for receiving of the data in the second optical signals.

Claims

CLAIMS1 . An apparatus (100) configured to transmit and receive free space optical signals; the apparatus comprising: a plurality of optical lenses (102) configured to transmit first optical signals, and receive at least one second optical signal; wherein the plurality of optical lenses (102) are spaced apart on the apparatus; an optical lens system (106) configured to align the first optical signals; wherein each of the plurality of the optical lenses (102) is configured to transmit a said first optical signal with a different wavelength than the other of the plurality of the optical lenses (102).

2. The apparatus of claim 1 , further comprising a plurality of optical transmitters, wherein each optical transmitter is connected to an optical lens (102) and configured to generate the first optical signal.

3. The apparatus of claim 1 or 2 further comprising a microwave apparatus configured to transmit and receive microwave frequency signals.

4. The apparatus of claim 3 wherein the microwave apparatus comprises a dish (102), and wherein the plurality of lenses (102) are spaced apart on the dish.

5. The apparatus of claim 4 wherein the plurality of lenses (102) are spaced apart on or adjacent to a periphery of the dish (104).

6. The apparatus of claim 4 or 5 wherein the microwave apparatus comprises a microwave feeder, wherein the feeder is located between the optical lens system and the dish.

7. The apparatus of any one of claims 3 to 6 wherein the apparatus is configured to transmit the first optical signals in a same direction as the microwave frequency signals.

8. The apparatus of any one of the preceding claims wherein the apparatus comprises optical circuitry (108) which is optically connected to the lenses (102), wherein the optical circuitry comprises a plurality of optical transmitters, wherein each optical transmitter is connected to an optical lens (102) and configured to generate the first optical signal; and the optical circuitry further comprises one or more receivers configured to receive the second optical signals.

9. The apparatus of any one of the preceding claims wherein the apparatus is configured to transmit the same first optical signal on the different wavelengths, or the apparatus is configured to transmit separate first optical signals on the different wavelengths.

10. A method (200) of transmitting free space optical signals, comprising transmitting (206) first optical signals from a plurality of optical lenses to an optical lens system (106), wherein the plurality of optical lenses (102) are spaced apart on the apparatus, and each wavelength is transmitted by only one of the optical lenses; and aligning and transmitting (208) the first optical signals by the optical lens system (106).

11. The method of claim 10, further comprising: generating (222) the plurality of first optical signals comprising different wavelengths; transmitting (224) the different wavelengths to the plurality of optical lenses 102 spaced apart on the apparatus.

12. The method of claim 10 or 11 further comprising receiving second optical signals using the apparatus, comprising receiving (242) second optical signals by the optical lens system (106) transmitting (244), by the optical lens system 106, the second optical signals to the plurality of lenses (102); and transmitting (246), by the plurality of lenses 102, the second optical signals to the optical circuitry for receiving second optical signals.

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