Frequency and Bandwidth Agile Optical Bench

Abstract

An optical bench that utilizes a narrowband optical filter on a precision rotary stage to provide custom tuning of the operating frequency of the optical bench while maintaining the ability to switch between narrowband and broadband operation of the optical bench. The precision rotary filter may further provide for dynamic reconfiguration of the optical bench to alternative frequencies for system interoperability, enablement of additional self-test capabilities, and relaxation of its manufacturing tolerances.

Description

Technical Field

[0001]

[0001] This disclosure generally relates to wireless communication systems. More specifically, in one example, this disclosure relates to an optical bench for use in an optical-based wireless communication system.

Background Art

[0002]

[0002] As communication technologies advance, there is a continuing need for improved, high-speed, reliable, and secure wireless communication and wireless data transmission of large amounts of information. Conventionally, wireless communication and data transmission (collectively referred to herein as communication) typically utilize the transmission of radio frequency (RF) signals that use one or more antennas and / or arrays to transmit communication over a distance. However, conventional RF communication suffers from rapid signal attenuation over distance and dispersion of signals over large geographic areas. Additionally, RF signals are relatively easily intercepted by unintended receivers, either intentionally or accidentally, due to the geographical overlap of RF communication signals.

[0003]

[0003] An alternative to RF communication is the use of optical communication and / or laser communication, which are more suitable for long-distance communication because signals do not degrade over distance and they do not disperse over a wide area. Typically, such systems utilize an optical bench with narrowband optical filters at fixed frequencies for specific applications. In wireless applications where filtering has to be done in free space, having fixed filters can enable filtering and multiplexing of optical signals but is limited by the frequency of the intended application.

[0004]

[0004] In applications that use a spatial reception sensor such as a focal plane or quad cell detector where an optical bench is used to detect and / or track a signal, these fixed filters can limit their proper operation. One solution that has been adopted is to utilize a flipper mechanism that allows the optical bench to switch between broadband and narrowband operation by moving the filter into or out of the optical path. This makes the system more flexible and allows it to operate at alternative frequencies. However, the flipper mechanism provides that the filter is always either in or out of the optical path and does not allow for fine tuning of the filtering of the optical signal.

Summary of the Invention

[0005]

[0005] The present disclosure addresses these and other problems by providing an optical bench that utilizes a narrowband optical filter on a precision rotation stage that can provide custom tuning of the operating frequency of the optical bench while maintaining the ability to switch between narrowband and broadband operation of the optical bench. The precision rotation filter can further provide for dynamic reconfiguration of the optical bench to alternative frequencies for system interoperability, activation of additional self-test capabilities, and relaxation of its manufacturing tolerances.

[0006]

[0006] In one aspect, an exemplary embodiment of the present disclosure may provide a laser communication optical bench comprising at least one generator operable to generate an optical communication transmission beam at a first frequency along a transmission path, a rotation mechanism, and a filter carried by the rotation mechanism, wherein the rotation mechanism is operable to rotate the filter to any desired position between a first position where the filter is substantially orthogonal to the transmission path and a second position where the filter is substantially parallel to the transmission path and off the transmission path, and the filter is further operable to shift the center wavelength frequency of the transmission beam within a desired frequency band as it rotates between the first position and the second position. This exemplary embodiment or another exemplary embodiment may further provide that the transmission path of the optical bench operates in a narrow-band mode when the filter is at any position within the transmission path, and the transmission path of the optical bench operates in a wide-band mode when the filter is at the second position and off the transmission path. This exemplary embodiment or another exemplary embodiment may further provide at least one receiver operable to receive an optical communication reception beam from outside the optical bench along a reception path, a second rotation mechanism, and a second filter carried by the second rotation mechanism within the reception path, wherein the second rotation mechanism is operable to rotate the second filter to any desired position between a first position where the second filter is substantially orthogonal to the reception path of the reception beam and a second position where the second filter is substantially parallel to the reception path of the reception beam and off the reception path, and the second filter is further operable to shift the center wavelength frequency of the reception beam within a desired frequency band as it rotates between the first position and the second position.This exemplary embodiment or another exemplary embodiment may further provide a third rotation mechanism and a third filter carried by the third rotation mechanism within the reception path, where the third rotation mechanism is operable to rotate the third filter between a first position where the third filter is orthogonal to the reception path of the received beam and a second position where the third filter is parallel to the reception path of the received beam and is out of the reception path, and the third filter is further operable to shift the center wavelength frequency of the received beam within a desired frequency band as it rotates between the first position and the second position. This exemplary embodiment or another exemplary embodiment may further provide that the rotation mechanism, the second rotation mechanism, and the third rotation mechanism each further comprise a rotation motor and a position encoder. This exemplary embodiment or another exemplary embodiment may further provide that the third filter further comprises an etalon filter. This exemplary embodiment or another exemplary embodiment may further provide that the etalon filter is operable to reduce interference caused by the solar disk when the solar disk is within the field of view of the optical bench. This exemplary embodiment or another exemplary embodiment may further provide that the reception path further comprises a reception communication path and a capture and tracking sensor path. This exemplary embodiment or another exemplary embodiment may further provide at least one polarization beam splitter operable to direct at least a portion of the received beam to proceed along the reception communication path and at least another portion of the received beam to proceed along the capture and tracking path. This exemplary embodiment or another exemplary embodiment may further provide that when the second filter is within the reception path, the reception path of the optical bench operates in a narrowband mode, and when the second filter is in the second position and out of the reception path, the reception path of the optical bench operates in a broadband mode.

[0007]

[0007] In another aspect, an exemplary embodiment of the present disclosure includes generating an optical communication transmission beam from at least one beam generator, directing the transmission beam to travel along a transmission path on an optical bench, rotating a filter to a first position where the filter is orthogonal to the transmission path, filtering the transmission beam using the filter such that the filter has a required center wavelength for a desired wavelength of the transmission beam, rotating the filter to a second position where the filter is parallel to and offset from the transmission path and the transmission beam is not filtered, and operating the transmission path of the optical bench in a broadband mode when the filter is in the second position, thereby providing a method for tuning a laser communication optical beam. This exemplary embodiment or another exemplary embodiment may further include rotating the filter to a plurality of positions between the first position and the second position, and filtering the transmission beam using the filter to shift the center wavelength of the transmission beam across a frequency band as the filter rotates through each of the plurality of positions between the first position and the second position. This exemplary embodiment or another exemplary embodiment may further include receiving an optical communication reception beam from outside the optical bench along a reception path, directing the reception beam to travel along the reception path, rotating a second filter to a first position where the second filter is orthogonal to the reception path, filtering the reception beam using the second filter such that the second filter has a required center wavelength for a desired wavelength of the reception beam, rotating the second filter to a second position where the second filter is parallel to and offset from the reception path and the reception beam is not filtered, and operating the reception path of the optical bench in a broadband mode when the second filter is in the second position. This exemplary embodiment or another exemplary embodiment may further include rotating the second filter to a plurality of positions between the first position and the second position, and filtering the reception beam using the second filter to shift the center wavelength of the reception beam across a frequency band as the second filter rotates through each of the plurality of positions between the first position and the second position.This exemplary embodiment or another exemplary embodiment may further provide that rotating a filter in the transmission path and rotating a second filter in the reception path are respectively achieved via a first rotation motor and a position encoder, and a second rotation motor and a position encoder. This exemplary embodiment or another exemplary embodiment may further provide rotating a third filter to a first position where the third filter is orthogonal to the reception path, and filtering a received beam using the third filter to reduce interference from the solar disk when the solar disk is within the field of view of the optical bench, and rotating the third filter to a second position where the third filter is parallel to the reception path and out of the reception path and the received beam is not filtered by the third filter. This exemplary embodiment or another exemplary embodiment may further provide that rotating the third filter is achieved via a third rotation motor and a position encoder.

[0008]

[0008] Sample embodiments of the present disclosure are described in the following description, shown in the drawings, and specifically and clearly shown and described in the appended claims.

Brief Description of the Drawings

[0009]

Figure 1

[0009] FIG. 1 is a representative optical bench block diagram of a next-generation optical communication system according to one aspect of the present disclosure.

Figure 2A

[0010] FIG. 2A is an exemplary filter and rotation mount for use with an optical bench according to one aspect of the present disclosure.

Figure 2B

[0011] FIG. 2B is an operating diagram of an exemplary optical filter shown in a first position within an optical path according to one aspect of the present disclosure.

Figure 2C

[0012] FIG. 2C is an overhead operating view of an exemplary optical filter from FIG. 2B shown in a second position rotated completely out of the optical path, according to one aspect of the present disclosure.

Figure 3A

[0013] FIG. 3A is a conceptual diagram of angle tuning of an optical bandpass filter, according to one aspect of the present disclosure.

Figure 3B

[0014] FIG. 3B is a graphical representation of the corresponding shift at the center wavelength of the narrow passband resulting from the angle tuning of the optical bandpass filter from FIG. 3A, according to one aspect of the present disclosure.

Figure 4

[0015] FIG. 4 is an operational flowchart illustrating a method of use for an optical bench that includes one or more precision rotational optical filters thereon.

DETAILED DESCRIPTION

[0010]

[0016] Like numbers refer to like parts throughout the drawings.

[0011]

[0017] Referring to FIG. 1, an exemplary laser communication optical bench block diagram is shown and is generally designated as optical bench 10. The optical bench 10 can include a plurality of optical and associated elements and can be arranged in any suitable configuration, as further described herein. Accordingly, it will be understood that the exemplary bench block diagram shown in FIG. 1 is a non-limiting example of an optical bench and not a limiting example thereof.

[0012]

[0018] The optical bench 10 can be a laser communication optical system that generally includes a transmission path 12 and a reception path 14. Generally speaking, the transmission path 12 can include a plurality of components described below for generating and transmitting an optical signal such as a laser beam that exits the optical bench 10 and moves away from it. Similarly, the reception path 14 can include additional components further described below and can generally be defined as a part of the optical bench 10 that is operable to receive a remote optical signal therein and process the received signal. The reception path 14 can be further divided into a reception communication path 16 and a acquisition and tracking sensor (ATS) path 18.

[0013]

[0019] Continuing to refer to FIG. 1, the transmission path 12 and the reception path 14 can include a plurality of optical components selected according to the desired use and implementation of the optical bench 10. According to the exemplary system shown and described herein, the transmission path 12 can include one or more laser generators 20, one or more optical switches 22, one or more optical amplifiers 24, one or more collimators 26, one or more alignment and / or beam steering components such as an alignment wedge pair 28, one or more bandpass filters 30, and one or more absorbers 32. Both the transmission path 12 and the reception path 14 can share components such as one or more polarizing beam splitters (PBS) 34, one or more liquid crystal variable retarders (LCVR) 36, and one or more quarter-wave plates (QWP) 38 and other optical components as desired. The reception path 14 can further include one or more bandpass filters 40, one or more etalon filters 42, one or more continuous LCVRs 44, and one or more reception PBSs 46. The reception communication path 16, as a subset of the reception path 14, can further include one or more alignment and / or beam steering components such as an alignment wedge pair 48, one or more collimators 50, and one or more optical amplifiers 52. The ATS path 18, as a second subset of the reception path 14, can similarly include one or more alignment and / or beam steering components such as an alignment wedge pair 54 and one or more acquisition and tracking sensors 56.

[0014]

[0020] The laser generator 20 can be any suitable laser generator operable to generate and transmit an optical signal or a laser signal over a C-band telecommunications wavelength range (e.g., 1530 nm to 1565 nm), as determined by the desired implementation. It may include a generator carried with or on the optical bench 10, or alternatively, may include a remote generator operable to generate an optical laser and transmit this laser to the optical bench 10. According to another aspect, the laser generator 20 can be one or more tunable laser generators, which can be operable to generate low optical signals at a plurality of wavelengths over a desired wavelength range, as determined by the desired implementation.

[0015]

[0021] As shown in this specification, the laser generator 20 may include a first laser generator 20A and a second generator 20B, which may actually be any suitable wavelength within the C-band or may include it, but in this specification, they are shown as the first "blue" laser generator 20A and the second "red" laser generator 20B. The terms blue and red are understood to be relative terms. The first laser generator 20A is operable to generate a beam biased towards the blue side of the C-band spectrum, and the second laser generator 20B is operable to generate a laser biased towards the red side of the C-band spectrum. Thus, as used in this specification, the blue laser and the red laser are relative to each other. For example, the first "blue" laser generator 20A may generate a beam at a wavelength of approximately 1550 nm, and the second "red" laser generator 20B may generate a beam at a wavelength of approximately 1555 nm. Thus, in this example, the second "red" beam generator 20B generates a beam biased towards the red side of the spectrum relative to the first "blue" laser generator 20B. Also in this case, the laser generator 20 may be operable to generate a laser at any suitable wavelength, and further or alternatively, it may be understood that it may be a tunable generator operable to generate a beam at a variable wavelength as desired.

[0016]

[0022] The optical switch 22 can be a standard and / or commercially available optical switch configured to enable switching between a first laser from the first laser generator 20A (simply referred to as the first laser 20A in this specification) and a second laser from the second laser generator 20B (referred to as the second laser 20B in this specification). If the laser generator 20 is tunable, the generator 20 can be tuned to change the wavelength of the laser, so the use and / or inclusion of the optical switch 22 is optional. Alternatively, the optical switch 22 can further be operable to combine the first and second lasers 20A and 20B as desired.

[0017]

[0023] The optical amplifier 24 can be any suitable optical amplifier operable to amplify an optical signal to a predetermined optical power. According to one example, the optical amplifier can be a high-power amplifier operable to amplify a signal with an amplification power from one-tenth watt (0.1) to 20 (twenty) watts.

[0018]

[0024] The transmit fiber collimator 26 can be any suitable collimator operable to reconfigure a transmitted or transmit beam (shown as beam 66 and further described below) to propagate through open air. According to one aspect, each of the laser generator 20, the optical switch 22, and the optical amplifier 24 can propagate a signal through an optical fiber cable (shown as the thin arrow within the transmission path 12) to advance the transmit beam 66 through the transmission path 12, as further described below. The transmit fiber collimator 26 can then be operable to convert the transmit beam 66 from a signal carried on a cable to an open-air optical signal (shown by the thick arrow within the transmission path 12), as determined by the desired implementation. In other words, the transmit fiber collimator 26 can convert the beam 66 from the optical fiber cable to an optical beam 66 operating in free space.

[0019]

[0025] The transmit alignment wedge pair 28 can be a standard optical wedge operable to steer or otherwise direct the beam 66 within the optical bench 10. The wedge pair 28 can be aligned to steer the beam 66 from the collimator 26 so as to align with the transmission path of the optical bench 10. Alternatively, the wedge pair 28 can be or include any other suitable steering optical component operable to direct the beam 66 within the optical bench 10.

[0020]

[0026] Referring to FIGS. 1 and 2A, the transmit BPF 30, described in more detail below, can be operative to tune the filter passband to any wavelength within the desired transmit frequency band and filter out any wavelength light that is not the desired or target wavelength for the transmit beam 66. This can help prevent contamination of the receive path 14 by stray light from the transmit path 12. The transmit BPF 30 can include a filter cell 58, such as a filter cell that can be carried within a filter cell mount 60 or otherwise securely fixed. As illustrated herein, the cell mount 60 and the filter cell 58 can generally be circular, although it will be understood that both components can have any suitable shape. As described in more detail below with respect to its operation, the transmit BPF 30 can be rotated at any angle between 0 and 90 degrees with respect to the path of the beam 66 to tilt-tune the wavelength of the beam 66. When the transmit BPF 30 is rotated to 0 degrees (i.e., orthogonal to the beam path 66 - see, e.g., FIG. 2B), the beam 66 will have the exact required center wavelength with respect to the desired transmit wavelength. When the transmit BPF 30 is rotated to 90 degrees (i.e., parallel to the beam path 66 and completely off the beam path 66 - see, e.g., FIG. 2C), the transmit beam 66 will not be filtered and the transmit path 12 of the optical bench 10 will operate at a broadband frequency as generated by the laser generator 20. As further described below, rotating the transmit BPF 30 at an angle between 0 and 90 degrees will effectively shift the center wavelength of the filter passband to other frequencies within the desired transmit frequency band for the beam 66. According to one aspect, a smaller rotation range can be used to tune the passband of the beam 66 for operation within the desired frequency band. For example, if the target frequency band is the C-band, the rotation angle can be between 0 and 15 degrees for operational tuning, while 90 degrees can still be used to remove the transmit BPF 30 from the path of the beam 66.

[0021]

[0027] The transmission BPF 30 may further include a cell mount support plate 62, which may function to connect the cell mount 60 and the filter cell 58 to the rotation mechanism 64. The cell mount support plate 62 may simply be any suitable structure operable to support the filter cell 58 and the cell mount 60 relative to the rotation mechanism 64, may have any suitable shape and / or configuration, and may be formed as an integral part of the cell mount 60 or as a separate component operable to connect thereto.

[0022]

[0028] As described herein, the rotation mechanism 64 can be any suitable rotation stage device operable to support the filter cell 58, the cell mount 60, and the cell mount support plate 62 while maintaining the ability to rotate these components to any angle between 0 and 90 degrees. According to one aspect, the rotation mechanism 64 can be a standard rotary motor and encoder, or other similar rotary device as determined by the desired implementation. The operation of the rotation mechanism is further described below. According to an example, the rotation mechanism 64 can be a precision rotary encoder operable to rotate the filter cell to any position between 0 and 90 degrees with respect to the path of the transmission beam 66 while providing precise position measurement of the filter cell 58. Knowing the precise position of the encoder means knowing the precise angle of the filter cell 58 with respect to the beam 66, which can then provide a very accurate calculation of the effect that the angle of the filter cell 68 will have on the center wavelength of the beam 66. In other words, knowing the exact angle of the filter cell 58 enables a precise calculation of the shift at the center wavelength of the beam 66, as further described below. Thus, according to this example, using a precision encoder and motor as the rotation mechanism 64 enables precise tuning of the beam 66 to any desired frequency within the target frequency band. The reverse is also true, i.e., knowing the desired center wavelength for the beam 66 enables a precise determination of the angle of the filter cell 58 required to cause the desired shift. In this case, including a precision rotary encoder and motor as the rotation mechanism 64 also enables rotating the transmit BPF 30 to a specific angle with respect to the path of the beam 66 to cause a desired shift in the center wavelength.

[0023]

[0029] According to one aspect, the optical bench 10 may further include or utilize one or more feedback loops to provide corrective feedback to help reduce any residual errors caused by the operation of the optical bench 10 and its components based on the installation environment and / or its usage time. For example, the optical bench may use one or more of self-test transmit / receive loopback feedback, receive operation feedback, and / or transmit operation feedback. Each of these types of feedback loops may provide data regarding the position of the filter cell 58 with respect to the beam 66 and the center wavelength of the beam 66. If any errors are found, this data may be used to offset or otherwise correct the factory calibration during normal operation.

[0024]

[0030] The transmission path 12 may further include one or more absorbers or absorbent surfaces 32, which may be operable to reflect out of the path of the beam 66 or otherwise absorb stray or deviated portions of the beam 66 that travel out of the path of the beam 66. According to one example, as the transmission BPF 30 rotates, a small portion of the beam 66 may be reflected away from the beam path, and the absorber may capture these deviated portions and may further help prevent stray wavelength light from contaminating the receive path 14.

[0025]

[0031] As described above, PBS34 can be shared by both the transmission path 12 and the reception path 14 in that it can encounter the transmission beam 66 when the transmission beam 66 moves through the optical bench 10 and exits, and it can also encounter the reception beam 68 when the reception beam 68 enters and moves along the reception path 14. The PBS can be any suitable optical splitter operable to pass a certain wavelength of light (such as the reception beam 68) while reflecting other wavelengths (such as the transmission beam 66). According to one aspect, PBS34 can be a pellicle, a standard optical lens, an optical wedge, or any other optical component operable to function as described herein. According to another aspect, PBS34 can be further operable to enable signals (plural) to be multiplexed based on polarization.

[0026]

[0032] Similar to PBS34, LCVR36 can be shared between the transmission path 12 and the reception path 14 in that it can encounter both the transmission beam 66 and the reception beam 68 during operation. However, in normal operation, LCVR36 only passively encounters the reception beam 68 and typically does not modify or change the beam 68 when the reception beam 68 moves into the optical bench 10. In other words, LCVR36 operates in the transmission path 12 but can be omitted from the reception path 14 as determined by its specific implementation.

[0027]

[0033] LCVR36 can be a binary LCVR operable to control the phase to correct the polarization of the transmission beam 66 and / or the reception beam 68 as desired. Since LCVR36 is not necessary for the functional operation of the optical bench 10, it can be an optional component. However, when the transmission BPF 30 is used to rotationally tune or micro-tune the transmission beam 66, it may also be desirable to utilize the binary LCVR36 to change or shift the polarization of the transmission signal 66.

[0028]

[0034] The QWP38 can also be shared in both the transmission path 12 and the reception path 14, or can be bypassed in one or both of the paths 12 and 14 as required. The QWP28 can work in conjunction with the LCVR36 to enable full control over the polarization of the transmission beam 66. According to one example, the transmission beam 66 can be linearly polarized as it moves through the optical bench 10, as determined by the desired implementation, and then converted to have circular polarization as it passes through the LCVR36 and the QWP38, and can exit the optical bench 10 and be transmitted away therefrom.

[0029]

[0035] As described above, the reception path 14 can include one or more reception BPFs 40 that can be substantially the same as or identical to the transmission BPF 30 in that the reception BPF 40 can similarly include a filter cell 58, a cell mount 60, a cell mount support plate 62, and a rotation mechanism 64.

[0030]

[0036] The receiving BPF 40 can be operable to tune the filter bandpass for the received beam 68 to any wavelength within a desired received frequency band and filter out any wavelength light that is not the desired or target wavelength for the received beam 68. This can help prevent contamination of the receiving path 14 by stray light from the receiving path 14 and can further enable the optical bench 10 to be tuned for higher sensitivity on the receiving path 14. Similar to the transmitting BPF 30, and as will be described in more detail below with respect to its operation, the receiving BPF 40 can be rotated to any angle between 0 and 90 degrees with respect to the path of the beam 68 to tilt-tune the wavelength of the beam 68. When the receiving BPF 40 is rotated to 0 degrees (i.e., orthogonal to the beam path 68 - see, e.g., FIG. 2B), the beam 68 will have the exact required center wavelength with respect to the desired received wavelength. When the receiving BPF 40 is rotated to 90 degrees (i.e., parallel to the beam path 68 and completely off the beam path 68 - see, e.g., FIG. 2C), the received beam 68 will not be filtered and the receiving path 14 of the optical bench will operate at broadband frequencies. As will be further described below, rotating the receiving BPF 40 to an angle between 0 and 90 degrees will effectively shift the center wavelength of the beam 68 to other frequencies within the desired received frequency band. Similar to the transmitting BPF 30, according to one aspect, a smaller rotation range can likewise be used to tune the passband of the beam 68 for operation within a desired frequency band. For example, if the target frequency band is the C band, the rotation angle can be between 0 and 15 degrees for operational tuning, while 90 degrees can still be used to remove the receiving BPF 40 from the path of the beam 68.

[0031]

[0037] The etalon filter 42 can be substantially similar to the transmit BPF 30 and / or the receive BPF 40 in that it can be a filter attached with a rotation mechanism 64 to enable rotational movement and adjustment to the filter position, as further described below. The etalon filter 42 can be different from the receive BPF 40 and / or the transmit BPF 30 in that the filter cell 58 itself can be an etalon filter cell for enabling very narrow-band filtering of the received signal 68, as further described below. The etalon filter 42 can be further operable and / or beneficial when filtering out direct sunlight, such as when the sun itself is within the field of view of the optical bench 10. In cases where it is not needed, the etalon filter 42 can be rotated out of the receive path 14 as desired. When broadband reception operation is desired, the etalon filter 42 can be rotated out of the receive path 14 together with the receive BPF 40, thus enabling broadband operation of the optical bench 10 along the receive path 14.

[0032]

[0038] According to one example, similar to the transmit BPF 30, the rotation mechanism 64 for the receive BPF 40 and the etalon filter 42 can be a precision rotary encoder that can enable accurate and precise calculation of the degree of shift at the center wavelength of the received beam 68, as described herein, and vice versa. Similarly, the receive path 12 can utilize one or more feedback loops to ensure precise positioning and angling of the receive BPF 40 and / or the etalon filter 42 over time and during normal operation of the optical bench 10, as previously described herein.

[0033]

[0039] The continuous LCVR 44 can be any suitable LCVR operable to adjust or modify the polarization of the received signal 68 to control the amount of light guided through the polarization beam splitter 46 to the receive communication path 16 and the ATS path 18. The continuous LCVR 44 can be operable to adjust the polarization of all or a portion of the received signal 68 to adjust or otherwise determine the percentage of light traveling through each path 16 and / or 18.

[0034]

[0040] For example, the continuous LCVR 44 may allow any percentage of light to travel through any of the paths 16 and / or 18, such as 100 percent of the light traveling through the ATS path 18, 50 percent of the light traveling through each of the paths 16 and 18, or any other suitable distribution depending on the determined use and particular operation of the optical bench 10, at the instant the received beam 68 encounters the continuous LCVR 44. According to another aspect, the continuous LCVR 44 is considered to be continuous in that it may adjust these percentages in real time to allow for a fluid and dynamic determination and change in the amount of light traveling through each of the paths 16 and / or 18.

[0035]

[0041] Similar to the transmit PBS 34, the receive PBS 46 can be any suitable or standard polarization beam splitter operable to multiplex the received signal 68 and split the signal to each of the aforementioned paths 16 and / or 18.

[0036]

[0042] As described above, the receive communication path 16 may further include one or more receive communication alignment wedge pairs 48, which can be any suitable or standard wedge pair or similar steering optics as determined by the desired implementation. The receive communication path 16 may additionally include a receive communication collimator 50 and an optical amplifier 52. The receive collimator 50 can be substantially similar to the transmit collimator 26, but operates in reverse in that it can acquire the received beam 68 traveling through free space and collimate it for transmission to the low-noise optical fiber amplifier 52. The low-noise optical fiber amplifier 52 can acquire the lower-power received signal 68 and be operable to amplify it to a power level usable for further processing by the communication system.

[0037]

[0043] As described above, the ATS path 18 may include one or more alignment wedge pairs 54, which may be standard optical wedges operable to steer or otherwise direct the beam 68 within the optical bench 10. The wedge pairs 54 may be aligned to steer the portion of the beam 68 from the successive LCVRs 44 that travels through the ATS path 18. According to one aspect, the ATS alignment wedge pairs 54 may direct at least a portion of the received signal 68 to a capture and tracking sensor 56, which may be any suitable capture and tracking sensor. According to one aspect, the capture and tracking sensor 56 may be a shortwave infrared acquisition focal plane sensor that utilizes silicon optics within the sensor path using narrowband filtering. According to another aspect, the sensor 56 may be any suitable capture sensor contemplated for use with an optical signal that enables tracking and alignment of the optical bench according to a desired implementation. For example, the capture and tracking sensor may be utilized to align the optical bench 10 with a known location or point, such as a celestial target, and then properly position and align the optical bench 10 to the appropriate position for its desired operation.

[0038]

[0044] The elements and components of the optical bench 10 have been described as such, and its operation and use will be described in even more detail.

[0039]

[0045] Referring to FIGS. 2A - 2C, most of the components and elements of the optical bench 10 can be standard or commercially available optical components and can operate or be used according to their known and expected functions. However, as previously described herein, most optical benches utilized in optical communication or laser communication operate with a filter fixed at a specific frequency or, alternatively, with a filter operated by a flipper mechanism to enable both broadband and narrowband operation. Systems operating on a fixed filter are typically limited to either broadband or narrowband operation alone, while systems utilizing a flipper mechanism can alternate between narrowband and broadband, but these systems are limited in that they can have at most two alternating states. Specifically, these systems can be limited to narrowband operation with the filter flipped into the beam path or to broadband with the filter removed from the beam path. The specific operating frequency is set by the presence or absence of a filter in the beam path and can be either non - tunable or, otherwise, precisely angle - tuned to shift the optical signal wavelength. This imparts rigidity to current systems, which can further result in transmit and receive crosstalk and / or self - interference.

[0040]

[0046] As previously described herein, the optical bench 10 can differ in the utilization of the rotary stages BPF30 and 40 and / or the etalon rotary stage filter 42. In particular, each of these filters can generally have a similar structure and can be substantially identical in structure (except that the specific filter cell 58 can vary depending on the desired implementation and based on its position within the optical bench - for example, the filter cell 58 can vary between the transmit BPF30 and the receive BPF40, etc.) and can be generally similar to the filters shown in FIG. 2A as filters 30, 40, and 42. Thus, this exemplary illustration is understood to apply equally to all filters 30, 40, and / or 42 unless otherwise specified.

[0041]

[0047] Continuing to refer to FIGS. 2B and 2C and further referring to FIG. 1, an exemplary positioning of the rotating filter is shown and can be described with reference to the transmission beam 66 and the reception beam 68 (which are generally shown in exemplary form). Generally shown there is a filter (30, 40, and / or 42) that can be located between two adjacent optical elements, which can vary depending on the particular implementation. For example, the transmission BPF 30 can be between the wedge pair 28 and the PBS 34, and the reception BPF 40 can be between the PBS 34 and the etalon filter 42. Thus, as illustrated there, the adjacent components are generally shown as representing relative positions and are not shown as limiting examples of specific components adjacent to both sides of the filters 30, 40, and / or 42.

[0042]

[0048] Then, as shown in FIG. 2B, the filters 30, 40, and / or 42 can be rotated by the precision rotation mechanism 64, which, according to this example, can be a rotation motor and a rotation position encoder having a resolution of 0.01 degrees and a repeatable / accuracy of 0.03 degrees. The rotation mechanism 64 is operable to rotate the filters 30, 40, and / or 42 from 0 degrees to 90 degrees between a first position (i.e., 0° as shown in FIG. 2B) where the filters 30, 40, and / or 42 are orthogonal to the paths of the beams 66, 68 and a second position (i.e., 90° as shown in FIG. 2C) where the filters 30, 40, and / or 42 are completely removed from the path of the reception beam 68. This rotational movement is indicated by the movement arrow A in FIG. 2C.

[0043]

[0049] As described herein, this rotational ability not only provides narrowband filtering when filters 30, 40, and / or 42 are in the paths of beams 66, 68, but can also provide broadband operation when filters 30, 40, and / or 42 are removed from beam paths 66, 68. Further, to avoid crosstalk, the ability to angularly tune filters 30, 40, and / or 42 to adjust the center wavelength of the signal passband to an alternative frequency at any position between 0 and 90 degrees enables the system to switch between low wavelength configurations and further enables the optical bench 10 to tune the operating center wavelength to alternate between multiple frequencies using a single system. This can provide additional flexibility both in avoiding crosstalk and in compatibility with other remote optical communication systems since transmission path 12 and reception path 14 are not limited to the use of a single frequency.

[0044]

[0050] Referring to FIGS. 3A and 3B and continuing to refer to FIG. 1, a concept of using an optical bench 10 having a rotational stage transmit BPF 30, a receive BPF 40, and an etalon filter 42 to provide precise angular tuning of transmit beam 66 and receive beam 68 to switch or otherwise shift the beam within a desired frequency band is illustrated in FIG. 3A using an exemplary filter cell 58. The passing arrow represents one of transmit beam 66 and receive beam 68. As indicated by arrow B, the filter cell 58 can be rotated in either direction, which can cause a shift at the center wavelength of the desired frequency band. Rotation of the filter cell 58 to any position between 0 and 90 degrees enables full tunability in that the center wavelength of beam 66 or 68 can be shifted to any frequency within the desired frequency band.

[0045]

[0051] This shift is shown generally and conceptually in the graph of FIG. 3B. Specifically, FIG. 3B illustrates the transmissibility or level of transmission of a particular wavelength through filter cell 58. The reference letter “T” on the y-axis represents the transmissibility or transmittance of each wavelength through filter cell 58. The “λ” symbol on the x-axis represents the wavelength of beams 66, 68 moving through filter cell 58.

[0046]

[0052] As shown, the first center wavelength is indicated by reference numeral X and represents the frequency having the highest center wavelength transmissibility. This peak wavelength X can then shift across the frequency band as filter cell 58 is rotated in one direction (e.g., clockwise), as represented by the subsequent center wavelengths at reference numerals Y and Z. As filter cell 58 continues to rotate in the same direction, the center wavelength of beam 66 or 68 will continue to shift until filter cell 58 rotates out of the path of beam 66 or 68 (e.g., when cell 58 is 90 degrees with respect thereto).

[0047]

[0053] In particular, when filter cell 58 is at 0 degrees (i.e., the optical beam 66 or 68 is incident perpendicularly on filter cell 58), the passband will be at its longest center wavelength (position X in FIG. 3B). As filter cell 58 is rotated to higher angles of incidence, the center wavelength of the passband becomes shorter (i.e., also moves to the left on the plot of FIG. 3B, as represented at reference numerals Y and Z in this case). As described above, the range of tuning angles for filter cell 58 can be less than the full range of 0 to 90 degrees. According to one example, when the region of interest is the C-band, the rotation range can be 0 to 15 degrees. The rotation mechanism 64 also provides the ability to rotate filter cell 58 to the 90-degree position and out of the path of beams 66 and / or 68 for wideband (i.e., filterless) operation.

[0048]

[0054] When the filter cell 58 is out of the paths of the beams 66, 68, the entire spectrum of the frequency band becomes available and the optical bench 10 can operate in a wide band. If the rotation direction of the filter cell 58 is reversed (e.g., counterclockwise), the filter cell 58 moves back into the path of the beam 66 or 68 again, and the central wavelength shifts in the opposite direction and returns to the first position / first central wavelength X, which can represent the exact required central wavelength for the desired wavelength of the beam 66 or 68 (i.e., the central wavelength when the filter cell 58 is at 0 degrees and perpendicular to the path of the beam 66 or 68).

[0049]

[0055] The etalon filter 42 can operate similarly, but it will be understood that the etalon filter 42 can have a very narrow operating frequency band for extremely narrowband filtering. According to one example, this extremely narrowband filtering is beneficial when the optical bench 10 is oriented such that the solar disk (i.e., the sun) directly enters the field of view of the optical bench. If the operation of the optical bench 10 does not require this very narrow filtering provided by the etalon filter 42, the etalon filter 42 can be rotated 90 degrees and move out of the path of the received beam 68, while the transmit BPF 30 and the receive BPF 40 can operate as normal as described herein. Alternatively, in implementations where the extremely narrowband filtering provided by the etalon filter 42 is not required or is undesirable, the etalon filter 42 can be completely omitted from the optical bench 10.

[0050]

[0056] Referring to FIG. 4, the operation of the exemplary transmit path 12 of the exemplary optical bench 10 is illustrated by an operational flowchart as process 100. First, at reference numeral 102 in process 100, the optical bench 10 can generate an optical communication transmit beam 66 from one or more laser generators 20 and further direct that beam 66 to proceed along the transmit path 12 using the various components described above herein.

[0051]

[0057] As the transmission beam 66 moves along the transmission path 12, the transmission BPF 30 can be rotated into the path of the beam 66 until the filter cell 58 reaches a first position orthogonal to the path of the beam 66. At this first position, the beam 66 can be filtered to have the correct required center wavelength as described above. Rotating the transmission BPF 30 to the first position is shown at reference numeral 104 during process 100, while filtering the beam 66 to the required center wavelength is shown at reference numeral 106.

[0052]

[0058] During the operation of the transmission path 12 of the optical bench 10, the transmission BPF 30 and the filter cell 58 can be rotated to any of a plurality of positions or angles between a first position and a second position where the filter is out of the path of the transmission beam 66. The operation of rotating the transmission BPF 30 and the filter cell 58 to a plurality of positions is shown at reference numeral 108 during process 100.

[0053]

[0059] Next, as shown at reference numeral 110, as the transmission BPF 30 and the filter cell 58 rotate through a plurality of positions, the center wavelength of the beam will shift across the desired frequency band of interest as previously described herein.

[0054]

[0060] Although not shown in FIG. 4, it will be understood that the operation of the reception BPF 40 and / or the etalon filter 42 can be similarly implemented as previously described herein.

[0055]

[0061] Although described herein as optical benches for use in optical or laser communication, these are exemplary uses of an optical bench 10 that utilizes a rotating stage transmitting BPF 30, a rotating stage receiving BPF 40, and / or a rotating stage etalon filter 42, and it will be further understood that the optical bench 10 can be readily adapted for use in other optical and / or laser transmission systems, or any other suitable transmission system. According to one aspect, some general applications that can benefit from the concepts described herein can include satellite communication between satellites in orbit, low-earth orbit communication between a low-earth orbit satellite and a ground or land-based facility, and other land-based or space-based applications as desired. Thus, it will be understood that the particular operational perimeters, including the desired and / or specific wavelengths utilized in both the generation of the laser by the laser generator 20 and the operation and rotation of the filters 30, 40, and / or 42, can vary depending on the particular implementation and operational requirements of the optical bench 10. However, the use of the rotating stage BPFs 30 and 40 and the etalon filter 42 can enable, or otherwise permit, a switchable mode between narrowband filtering and broadband filtering of the optical path, along with precise tunable narrowband filtering. This further enables operational flexibility through precise tilt tuning of the filters 30, 40, and / or 42, while at the same time improving manufacturability by relaxing tolerances on the filters and enabling further automation of the alignment of the filters. This further represents a significant improvement over systems that utilize a flipper mechanism to switch between a fixed filter system and / or narrowband and broadband filtering of the optical path.

[0056]

[0062] As described herein, aspects of the present disclosure may include one or more electrical, pneumatic, hydraulic, mechanical, or other similar secondary components and / or systems therein. Accordingly, the present disclosure is intended and understood to include any necessary operating components thereof. For example, it will be understood that electrical components may include any suitable and necessary wiring, fuses, or the like for their normal operation. Similarly, any mechanical actuator may include any secondary or peripheral components such as piezoelectric, gears, electric motors, switches, or the like. It will be further understood that any connection between various components not explicitly described herein may be made through any suitable means, including mechanical fasteners, or more permanent attachment means such as welding or the like. Alternatively, where feasible and / or desirable, the various components of the present disclosure may be integrally formed as a single unit.

[0057]

[0063] Various inventive concepts may be embodied as one or more methods, and an example thereof has been provided. The operations performed as part of the method may be ordered in any suitable manner. Accordingly, embodiments may be configured in which the operations are performed in an order different from that shown, which may include performing some operations simultaneously, even if in the exemplary embodiments they are shown as sequential operations.

[0058]

[0064] Although various embodiments of the present invention have been described and illustrated herein, those skilled in the art will readily envision various other means and / or structures for obtaining one or more of the advantages and / or results described herein and / or for performing the functions, and each such variation and / or modification is to be regarded as within the scope of the embodiments of the invention described herein. More generally, those skilled in the art will readily understand that all parameters, dimensions, materials, and configurations described herein are intended to be exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on one or more specific applications in which the teachings of the invention are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Accordingly, the foregoing embodiments are presented by way of example only, and it is to be understood that embodiments of the invention may be practiced otherwise than as specifically described and claimed within the scope of the appended claims and their equivalents. Embodiments of the invention disclosed herein are directed to each and every distinct feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the scope of the invention disclosed herein if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

[0059]

[0065] All definitions defined and used herein are to be understood as controlling over dictionary definitions, definitions in incorporated by reference documents, and / or ordinary meanings of defined terms.

[0060]

[0066] As used in this specification and the claims, the indefinite articles "a" and "an" are to be understood as meaning "at least one" unless the contrary is clearly indicated. The phrase "and / or" as used in this specification and the claims (if any) is to be understood as meaning "either or both" of the elements so joined, i.e., elements that are present conjunctively in some cases and disjunctively in other cases. A plurality of elements listed with "and / or" are likewise to be construed as meaning "one or more" of the elements so joined. Other elements other than those specifically identified by the "and / or" clause may be present optionally, whether or not they are related to those specifically identified elements. Thus, by way of non-limiting example, reference to "A and / or B", when used in conjunction with open-ended language such as "comprising", in one embodiment refers to only A (optionally including elements other than B), in another embodiment refers to only B (optionally including elements other than A), and in yet another embodiment refers to both A and B (optionally including other elements), and so on. As used in this specification and the claims, "or" is to be understood as having the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" is inclusive, i.e., including at least one of several elements or a list of elements, but more than one, and optionally, additional unlisted items as well. Terms that clearly indicate the contrary, such as "only one of" or "exactly one of", or when used in the claims, "consisting of", etc., will refer to including only one of several elements or a list of elements. Generally, the term "or" as used in this specification is to be construed as indicating exclusive alternatives (i.e., "either one or the other, but not both") only when followed by exclusive terms such as "either", "one of", "only one of", or "exactly one of". "Consisting essentially of", when used in the claims, shall have the ordinary meaning as used in the field of patent law.

[0061]

[0067] As used in this specification and the claims, the phrase "at least one" in reference to a list of one or more elements means at least one element selected from any one or more of the elements in the list of elements, but does not necessarily include at least one of every element specifically recited in the list of elements, and is understood not to exclude any combinations of elements in the list of elements. This definition also allows for elements to optionally be present, whether or not related to those specifically identified elements, in addition to those specifically identified elements within the list of elements referred to by the phrase "at least one". Thus, by way of non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B", or equivalently, "at least one of A and / or B") can, in one embodiment, refer to at least one that optionally includes more than one A and no B (and optionally includes elements other than B), in another embodiment can refer to at least one that optionally includes more than one B and no A (and optionally includes elements other than A), and in yet another embodiment can refer to at least one that optionally includes more than one A, and at least one that optionally includes more than one B (and optionally includes other elements), and so on.

[0062]

[0068] As used in this specification and the claims, the term "effecting" or a phrase or claim element that begins with the term "effecting" is to be understood to mean causing something to occur or bringing about something. For example, causing an event to occur can be caused by the action of a first party, whether or not a second party actually performs the event or the event occurs to the second party. Put another way, effecting refers to a party providing to another party a tool, object, or resource for causing an event to occur. Thus, in this example, the claim element "causing an event to occur" would mean that the first party provides to the second party the tools or resources necessary for the second party to perform the event, where a positive single action is the responsibility of the first party providing the tools or resources for causing the event to occur.

[0063]

[0069] When a feature or element is referred to herein as being "above" another feature or element, it can be directly above that other feature or element, or intervening features and / or elements may also be present. In contrast, when a feature or element is referred to as being "directly above" another feature or element, no intervening features or elements are present. When a feature or element is referred to as being "connected to", "attached to", or "coupled to" another feature or element, it will be understood that it can be directly connected, attached, or coupled to that other feature or element, or intervening features or elements may be present. In contrast, when a feature or element is referred to as being "directly connected to", "directly attached to", or "directly coupled to" another feature or element, no intervening features or elements are present. Although described or shown with respect to one embodiment, the features and elements so described or shown may also be applicable to other embodiments. Also, it will be understood by those skilled in the art that a reference to a structure or feature being "adjacent" to another feature may have portions that overlap or are beneath the adjacent feature.

[0064]

[0070] Spatially relative terms such as "under", "below", "lower", "over", "upper", "above", "behind", "in front of ~", and the like may be used herein for ease of description to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if the device in the figure is inverted, an element described as "under" or "beneath" another element or feature would then be oriented "over" the other element or feature. Thus, the exemplary term "under" can encompass both an over and an under orientation. The device may be otherwise oriented (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein are to be interpreted accordingly. Similarly, terms such as "upwardly", "downwardly", "vertical", "horizontal", "lateral", and the like are used herein for descriptive purposes only, unless specifically indicated otherwise.

[0065]

[0071] The terms "first" and "second" may be used herein to describe various features / elements, but these features / elements should not be limited by these terms unless the context indicates otherwise. These terms may be used to distinguish one feature / element from another. Thus, without departing from the teachings of the present invention, the first feature / element described herein can be referred to as the second feature / element, and similarly, the second feature / element described herein can be referred to as the first feature / element.

[0066]

[0072] An embodiment is an implementation form or example of the present disclosure. References in this specification to "embodiment", "one embodiment", "some embodiments", "one particular embodiment", "exemplary embodiment", or "other embodiments", or the like, mean that the particular features, structures, or characteristics described in connection with the embodiment are included in at least some embodiments of the present invention, but not necessarily all embodiments. The various occurrences of "embodiment", "one embodiment", "some embodiments", "one particular embodiment", "exemplary embodiment", or "other embodiments", or the like, do not necessarily all refer to the same embodiment.

[0067]

[0073] When a component, feature, structure, or characteristic is described in this specification as "may be included", "may be contained", or "can be included", that particular component, feature, structure, or characteristic need not be included. When this specification or the claims refer to "a" element, it does not mean that there is only one such element. When the specification or the claims refer to "additional" elements, it does not exclude the presence of more than one additional element.

[0068]

[0074] As used in this specification and the claims, including when used in examples, unless otherwise specified, all numbers may be read as if the word "about" or "substantially" preceded them even if the term does not explicitly appear. The phrases "about" or "substantially" can be used to indicate that the value and / or position being described is within a reasonable expected range when describing size and / or position. For example, a numerical value can have a value that is + / −0.1%, + / −1%, + / −2%, + / −5%, + / −10%, etc. of the recited value (or range of values). Any numerical range recited in this specification is intended to include all sub-ranges subsumed therein.

[0069]

[0075] In addition, the methods of carrying out the present disclosure may be performed in sequences different from those described herein. Accordingly, the sequences of the methods should not be read as limiting, unless specified. It will be appreciated that performing some of the steps of a method in a different order may achieve similar results.

[0070]

[0076] In the claims, as well as in the above specification, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “consisting of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” are to be considered closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examination Procedures.

[0071]

[0077] In the foregoing description, certain terms have been used for the sake of brevity, clarity, and understanding. Such terms are used for illustrative purposes and are intended to be broadly construed, and no unnecessary limitations should be implied therefrom beyond the requirements of the prior art.

[0072]

[0078] Furthermore, the descriptions and illustrations of the various embodiments of the present disclosure are examples, and the present disclosure is not limited to the exact details shown or described.

Claims

1. A laser communication optical bench, comprising: at least one generator operable to generate an optical communication transmission beam at a first frequency along a transmission path; a rotation mechanism; a filter carried by the rotation mechanism, wherein the rotation mechanism is operable to rotate the filter to any desired position between a first position where the filter is substantially orthogonal to the transmission path and a second position where the filter is substantially parallel to the transmission path and is out of the transmission path, and the filter is further operable to shift the center wavelength frequency of the transmission beam within a desired frequency band as it rotates between the first position and the second position.

2. The transmission path of the optical bench operates in a narrow-band mode when the filter is at any position within the transmission path, and the transmission path of the optical bench operates in a wide-band mode when the filter is at the second position and is out of the transmission path. The laser communication optical bench according to Claim 1.

3. at least one receiver operable to receive an optical communication reception beam from outside the optical bench along a reception path; a second rotation mechanism; a second filter carried by the second rotation mechanism within the reception path, wherein the second rotation mechanism is operable to rotate the second filter to any desired position between a first position where the second filter is substantially orthogonal to the reception path of the reception beam and a second position where the second filter is substantially parallel to the reception path of the reception beam and is out of the reception path, and the second filter is further operable to shift the center wavelength frequency of the reception beam within a desired frequency band as it rotates between the first position and the second position. The laser communication optical bench according to Claim 1.

4. a third rotation mechanism; a third filter carried by the third rotation mechanism within the reception path, The third rotation mechanism is operable to rotate the third filter to any desired position between a first position where the third filter is substantially orthogonal to the reception path of the received beam and a second position where the third filter is substantially parallel to the reception path of the received beam and is out of the reception path. The third filter is further operable to shift the center wavelength frequency of the received beam within a desired frequency band as it rotates between the first position and the second position. The laser communication optical bench according to claim 3.

5. The rotation mechanism, the second rotation mechanism, and the third rotation mechanism each further include a rotation motor and a position encoder The laser communication optical bench according to claim 4.

6. The third filter further includes an etalon filter The laser communication optical bench according to claim 4.

7. The etalon filter is operable to reduce interference caused by the solar disk when the solar disk is within the field of view of the optical bench. The laser communication optical bench according to claim 6.

8. The reception path further includes a reception communication path and a capture and tracking sensor path The laser communication optical bench according to claim 3.

9. At least one polarization beam splitter operable to direct at least a portion of the received beam to travel through the reception communication path and at least another portion of the received beam to travel through the capture and tracking path The laser communication optical bench according to claim 8.

10. The reception path of the optical bench operates in a narrow band mode when the second filter is at any position within the reception path, and the reception path of the optical bench operates in a wide band mode when the second filter is at the second position and is out of the reception path. The laser communication optical bench according to claim 3.

11. A method of tuning a laser communication optical beam, comprising: generating an optical communication transmission beam from at least one beam generator; directing the transmission beam to travel through a transmission path in an optical bench; rotating a filter to a first position where the filter is substantially orthogonal to the transmission path; Filtering the transmission beam using a filter so as to have a required center wavelength with respect to a desired wavelength of the transmission beam; Rotating the filter to a second position where the filter is substantially parallel to the transmission path and is out of the transmission path, and the transmission beam is not filtered; Operating the transmission path of the optical bench in a broadband mode when the filter is in the second position; A method comprising the above.

12. Rotating the filter to a plurality of positions between the first position and the second position; Filtering the transmission beam using the filter so as to shift the center wavelength of the transmission beam across a frequency band as the filter rotates through each of the plurality of positions between the first position and the second position; The method according to claim 11, further comprising the above.

13. Receiving an optical communication reception beam from outside the optical bench along a reception path; Guiding the reception beam to proceed along the reception path; Rotating a second filter to a first position where the second filter is substantially orthogonal to the reception path; Filtering the reception beam using the second filter so as to have a required center wavelength with respect to a desired wavelength of the reception beam; Rotating the second filter to a second position where the second filter is substantially parallel to the reception path and is out of the reception path, and the reception beam is not filtered; Operating the reception path of the optical bench in a broadband mode when the second filter is in the second position; The method according to claim 11, further comprising the above.

14. Rotating the second filter to a plurality of positions between the first position and the second position; Filtering the reception beam using the second filter so as to shift the center wavelength of the reception beam across a frequency band as the second filter rotates through each of the plurality of positions between the first position and the second position; The method according to claim 13, further comprising the above.

15. Rotating the filter in the transmission path and rotating the second filter in the reception path are each achieved via a first rotary motor and a position encoder, and a second rotary motor and a position encoder, respectively, the method according to claim 14.

16. Rotating a third filter to a first position where the third filter is substantially orthogonal to the reception path; Filtering the received beam using the third filter to reduce interference from the solar disk when the solar disk is within the field of view of the optical bench; Rotating the third filter to a second position where the third filter is substantially parallel to and out of the reception path and the received beam is not filtered by the third filter; The method according to claim 14, further comprising.

17. Rotating the third filter is achieved via a third rotary motor and a position encoder, the method according to claim 16.

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