WO2024099577A1

WO2024099577A1 - Optical apparatus and method for selective wavelength switching of light

Info

Publication number: WO2024099577A1
Application number: PCT/EP2022/081658
Authority: WO
Inventors: Aurelian Dodoc
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2022-11-11
Filing date: 2022-11-11
Publication date: 2024-05-16

Abstract

An optical apparatus (100) for selective wavelength switching of light is disclosed. The optical apparatus (100) comprises a first spatial light modulator, SLM, (120), wherein the first SLM (120) comprises a first area (120a) and a second area (120b) and wherein the first area (120a) of the first SLM (120) is configured to receive and redirect a first plurality of demultiplexed light waveband channels. Moreover, the optical apparatus (100) comprises a second SLM (160) positioned along an optical axis at a distance from the first SLM (120), wherein the second SLM (160) comprises a first area (160a) and a second area (160b) and wherein the second area (160b) of the second SLM (160) is configured to receive and redirect the first plurality of demultiplexed light waveband channels from the first area (120a) of the first SLM (120) to the second area (120b) of the first SLM (120). The optical apparatus (100) further comprises a plurality of lens arrangements positioned between the first SLM (120) and the second SLM (160) to receive and redirect the first plurality of demultiplexed light waveband channels from the first area (120a) of the first SLM (120) towards the second area (160b) of the second SLM (160) and to receive and redirect the first plurality of demultiplexed light waveband channels from the second area (160b) of the second SLM (160) towards the second area (120b) of the first SLM (120).

Description

Optical apparatus and method for selective wavelength switching of light

TECHNICAL FIELD

The present disclosure relates to optical technology for optical fiber communication networks. More specifically, the present disclosure relates to an optical apparatus and method for selective wavelength switching (also referred to as cross-connecting) of light.

BACKGROUND

Optical networks are networks that use optical signals to carry data. Light sources such as lasers generate optical signals. Modulators modulate the optical signals with data to generate modulated optical signals. Various components transmit, propagate, amplify, receive, and process the modulated optical signals, such as optical fibers and optical multiplexers/demultiplexers allowing to achieve higher bandwidths for optical networks. More details about switching architectures in optical networks can be found in the review article “Survey of Photonic Switching Architectures and Technologies in Support of Spatially and Spectrally Flexible Optical Networking”, Marom Dan, et. al., JOSA, VOL. 8, No. 1 , 2017.

SUMMARY

It is an objective of the present disclosure to provide an improved optical apparatus (herein also referred to as an optical multiplexer/demultiplexer) and method for selective wavelength switching of light.

The foregoing and other objectives are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect an optical apparatus for selective wavelength switching of light is provided. The optical apparatus comprises a first spatial light modulator, SLM, wherein the first SLM comprises a first area and a second area and wherein the first area of the first SLM is configured to receive and redirect a first plurality of demultiplexed light waveband channels. Moreover, the optical apparatus comprises a second SLM positioned along a main optical axis of the optical apparatus at a distance D from the first SLM. The second SLM comprises a first area and a second area, wherein the second area of the second SLM is configured to receive and redirect the first plurality of demultiplexed light waveband channels from the first area of the first SLM to the second area of the first SLM. The optical apparatus further comprises a plurality of lens arrangements positioned between the first SLM and the second SLM to receive and redirect the first plurality of demultiplexed light waveband channels from the first area of the first SLM towards the second area of the second SLM and to receive and redirect the first plurality of demultiplexed light waveband channels from the second area of the second SLM towards the second area of the first SLM. Thus, a more flexible optical apparatus for selective wavelength switching of light is provided with a flexible input/output functionality of the first and the second SLM. More specifically, unlike conventional optical switching devices, where the first and second SLM receive and redirect only input our output light waveband cannels, in the optical apparatus according to the first aspect both the first and the second SLM may receive and redirect both input and output waveband data channels, thus providing a larger flexibility. It is to be understood that the two areas of each of the two SLMs can be implemented also as two or more separate sub SLMs so that the two separate active areas are provided by two different sub SLMs with a synchronised steering procedure.

In a further possible implementation form, the first area of the second SLM is configured to receive and redirect a second plurality of demultiplexed light waveband channels and the second area of the first SLM is configured to receive and redirect the second plurality of demultiplexed light waveband channels from the first area of the second SLM to the second area of the second SLM. The plurality of lens arrangements are further configured to receive and redirect the second plurality of demultiplexed light waveband channels from the first area of the second SLM towards the second area of the first SLM and to receive and redirect the second plurality of demultiplexed light waveband channels from the second area of the first SLM towards the second area of the second SLM.

In a further possible implementation form, the first SLM and the second SLM have a substantially rectangular, in particular quadratic spatially extended portion, wherein the first area and the second area of the first SLM are defined by a first half and a second half of the rectangular, in particular quadratic spatially extended portion of the first SLM and wherein the first area and the second area of the second SLM are defined by a first half and a second half of the rectangular, in particular quadratic spatially extended portion of the second SLM.

In a further possible implementation form, the optical axis defines a first plane of symmetry and a second plane of symmetry perpendicular to the first plane of symmetry of the optical apparatus, wherein the first area of the first SLM and the first area of the second SLM are positioned on one side of the first plane of symmetry and the second area of the first SLM and the second area of the second SLM are positioned on an opposite side of the first plane of symmetry. In a further possible implementation form, the plurality of lens arrangements comprises a first, second and third lens arrangement. The first lens arrangement has a refractive power primarily in the first plane of symmetry. The second lens arrangement has a refractive power primarily in the second plane of symmetry, wherein the second lens arrangement is positioned between the first lens arrangement and the second SLM. The third lens arrangement has a refractive power primarily in the first plane of symmetry and is positioned between the second lens arrangement and the second SLM.

In a further possible implementation form, the first lens arrangement, the second lens arrangement and/or the third lens arrangement comprises one or more cylindrical lens elements.

In a further possible implementation form, the first SLM and/or the second SLM comprises a liquid crystal on silicon (LCOS) device and/or a digital mirror device.

In a further possible implementation form, the optical apparatus further comprises a first dispersive optical element configured to disperse one or more first input light beams into the first plurality of light waveband channels and to direct the first plurality of light waveband channels onto the first area of the first SLM and/or to receive the first plurality of light waveband channels from the second area of the first SLM and combine the first plurality of light channels from the second area of the first SLM into one or more output light beams.

In a further possible implementation form, the optical apparatus further comprises a second dispersive optical element configured to disperse one or more second input light beams into the second plurality of light waveband channels and to direct the second plurality of light waveband channels onto the first area of the second SLM and/or to receive the second plurality of light waveband channels from the second area of the second SLM and combine the second plurality of light waveband channels from the second area of the second SLM into one or more output light beams.

In a further possible implementation form, the first dispersive optical element and/or the second dispersive optical element comprises a grating, a prism and/or a grism.

In a further possible implementation form, the plurality of lens arrangements between the first SLM and the second SLM define an anamorphic optical system. In a further possible implementation form, the plurality of lens arrangements between the first SLM and the second SLM define an afocal optical system in one of the planes of symmetry.

According to a second aspect a method for selective wavelength switching of light by an optical apparatus, in particular the optical apparatus according to the first aspect is provided. The method comprises: receiving and redirecting a first plurality of demultiplexed light channels by a first area of a first SLM, wherein the first SLM further comprises a second area; receiving and redirecting by a second area of a second SLM the first plurality of demultiplexed light channels from the first area of the first SLM to the second area of the first SLM, wherein the second SLM is positioned along an optical axis of the optical apparatus at a distance D from the first SLM and further comprises a first area; receiving and redirecting, by a plurality of lens arrangements positioned between the first SLM and the second SLM, the first plurality of demultiplexed light channels from the first area of the first SLM towards the second area of the second SLM; and receiving and redirecting, by the plurality of lens arrangements positioned between the first SLM and the second SLM, the first plurality of demultiplexed light channels from the second area of the second SLM towards the second area of the first SLM.

The method according to the second aspect of the present disclosure can be performed by the optical apparatus according to the first aspect of the present disclosure. Thus, further features of the method according to the second aspect of the present disclosure, result directly from the functionality of the optical apparatus according to the first aspect of the present disclosure as well as its different implementation forms described above and below.

Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

Fig. 1 shows a schematic diagram illustrating an optical apparatus for selective wavelength switching of light according to an embodiment;

Fig. 2 shows two schematic cross-sectional side views of an optical apparatus for selective wavelength switching of light according to an embodiment;

Fig. 3 shows two schematic cross-sectional side views of an optical apparatus for selective wavelength switching of light according to a further embodiment; and Fig. 4 shows a flow diagram illustrating steps of a method for operating an optical apparatus for selective wavelength switching of light according to an embodiment.

In the following, identical reference signs refer to identical or at least functionally equivalent features.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

For instance, it is to be understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if one or a plurality of specific method steps are described, a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on one or a plurality of units, e.g. functional units, a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise.

Figure 1 shows a schematic diagram illustrating an optical apparatus (also referred to as optical multiplexer/demultiplexer) 100 for selective wavelength switching of light according to an embodiment from a plurality of input ports to a plurality of output ports. In the embodiment shown in figure 1 , the plurality of input ports comprises a first set A of input ports IA1-N/2 arranged on a first side of the optical apparatus 100 and a second set B of input ports I B1-N/2 arranged on an opposite second side of the optical apparatus 100. Likewise, the plurality of output ports comprises a first set A of output ports OA1-N/2 arranged on the second side of the optical apparatus 100 (adjacent to the second set of input ports) and a second set B of output ports OB1-N/2 arranged on the first side of the optical apparatus 100 (adjacent to the first set of input ports). Each input and output port may contain one or more data carrying waveband channels so that the optical apparatus 100 is configured to recombine and redirect a plurality of input data channels to the plurality of output ports. The input ports and/or output ports may be connected to optical fibers, wherein each optical fiber transmits the one or more data carrying waveband channels.

More specifically, the optical apparatus 100 comprises a first spatial light modulator, SLM, 120 and a second SLM 160 positioned along an optical axis OA (shown in figures 2 and 3) at a distance D from the first SLM 120. In an embodiment, the first and second SLM 120, 160 may be implemented, for instance, as a liquid crystal on silicon device and/or a digital mirror device. The first SLM 120 comprises a spatially extended first area 120a and a spatially extended second area 120b. As illustrated in figure 1 , the first SLM 120 and the second SLM 160 may have a substantially rectangular, in particular quadratic spatially extended planar surface portion, wherein the first area 120a and the second area 120b of the first SLM 120 are defined by a first half and a second half (referred to as A and B in figure 1) of the rectangular, in particular quadratic spatially extended surface portion of the first SLM 120. Likewise, the first area 160a and the second area 160b of the second SLM 160 may be defined by a first half and a second half (also referred to as A and B in figure 1) of the rectangular, in particular quadratic spatially extended planar surface portion of the second SLM 160. In a further embodiment, the two areas of the SLMs 120, 160 may also be implemented as separate sub SLMs with a synchronised steering procedure.

For generating the plurality of demultiplexed light channels in the plurality of wavebands (and vice versa) the optical apparatus 100 may further comprise a first dispersive optical element 110a,b and/or a second dispersive optical element 170a, b, as illustrated in figure 3. In an embodiment, the first dispersive optical element 110a,b and/or the second dispersive optical element 170a, b comprises a grating, a prism and/or a grism.

The first dispersive optical element 110a,b may be configured to disperse one or more first light beams into the first plurality of light waveband channels and to direct the first plurality of light waveband channels onto the first area 120a of the first SLM 120 and/or to receive the first plurality of light waveband channels from the second area 120b of the first SLM 120 and combine the first plurality of light waveband channels from the second area 120b of the first SLM 120 into one or more first output light beams. Likewise, the second dispersive optical element 170a, b may be configured to disperse one or more second light beams into the second plurality of light waveband channels and to direct the second plurality of light waveband channels onto the first area 160a of the second SLM 160 and/or to receive the second plurality of light waveband channels from the second area 160b of the second SLM 160 and combine the second plurality of light waveband channels from the second area 160b of the second SLM 160 into one or more second output light beams.

As will be described in more detail below, the first area 120a of the first SLM 120 is configured to receive and redirect the first plurality of demultiplexed light waveband channels provided by the first set of input ports IAI-N/2- Moreover, the second area 160b of the second SLM 160 is configured to receive and redirect, i.e. reflect the first plurality of demultiplexed light waveband channels from the first area 120a of the first SLM 120 to the second area 120b of the first SLM 120. Likewise, the first area 160a of the second SLM 160 is configured to receive and redirect a second plurality of demultiplexed light waveband channels provided by the second set of input ports IB1-N/2 to the second area 120b of the first SLM 120 and the second area 120b of the first SLM 120 is configured to receive and redirect the second plurality of demultiplexed light waveband channels from the first area 160a of the second SLM 160 to the second area 160b of the second SLM 160.

As schematically indicated in figure 1 , the optical apparatus 100 further comprises an optical system 180 arranged between the first SLM 120 and the second SLM 160 for guiding the light emitted by a respective portion of the first SLM 120 to a selectable desired portion of the second SLM 160 and vice versa. By way of example, as illustrated in figure 1 , the optical system 180 of the optical apparatus 100 may be configured to guide a first waveband A1 of the light provided by the input port IA1 onto the first waveband A1 of the light connected to the output port OA2. Likewise, the optical system 180 of the optical apparatus 100 may be configured to guide a first waveband A1 of the light provided by the input port IB1 onto the first waveband A1 of the light connected to the output port OBN/2.

As illustrated in figures 2 and 3, which show two schematic cross-sectional side views of the optical apparatus 100 in a first plane of symmetry, namely the Y-Z plane and in a second plane of symmetry, namely the X-Y plane defined by the optical axis OA, the optical system 180 of the optical apparatus 100 comprises a plurality of lens arrangements 130, 140, 150 positioned between the first SLM 120 and the second SLM 160. In the embodiments shown in figures 1 to 3, the first area 120a of the first SLM 120 and the first area 160a of the second SLM 160 are positioned on one side of the first plane of symmetry, i.e. the Y-Z plane, while the second area 120b of the first SLM 120 and the second area 160b of the second SLM 160 are positioned on an opposite side of the first plane of symmetry, i.e. the Y-Z plane. As will be appreciated, the plurality of lens arrangements 130, 140, 150 between the first SLM 120 and the second SLM 160 define an anamorphic optical system 180. In an embodiment, the plurality of lens arrangements 130, 140, 150 between the first SLM 120 and the second SLM 160 define an afocal optical system in one of the planes of symmetry.

The plurality of lens arrangements 130, 140, 150 are configured to receive and redirect the first plurality of demultiplexed light waveband channels from the first area 120a of the first SLM 120 towards the second area 160b of the second SLM 160 and to receive and redirect the first plurality of demultiplexed light waveband channels from the second area 160b of the second SLM 160 towards the second area 120b of the first SLM 120. Moreover, the plurality of lens arrangements 130, 140, 150 are configured to receive and redirect the second plurality of demultiplexed light waveband channels from the first area 160a of the second SLM 160 towards the second area 120b of the first SLM 120 and to receive and redirect the second plurality of demultiplexed light waveband channels from the second area 120b of the first SLM 120 towards the second area 160b of the second SLM 160.

In the embodiment shown in figures 2 and 3, the first lens arrangement 130 and the third lens arrangement 140 are implemented as a respective biconvex Y lens, i.e. a cylindrical lens having a positive refractive power only in the first plane of symmetry, i.e. the Y-Z plane. In further embodiments, the first lens arrangement 130 and the third lens arrangement 140 may comprise further optical elements and/or also have some refractive power in the second plane of symmetry, i.e. the X-Z plane, which, however, usually will be smaller than the primary refractive power in the first plane of symmetry, i.e. the Y-Z plane.

In the embodiment shown in figures 2 and 3, the central second lens arrangement 140 may be implemented as a biconvex X lens, i.e. a cylindrical lens having a refractive power only in the second plane of symmetry, i.e. the X-Z plane. In further embodiments, the second lens arrangement 140 may comprise further optical elements and/or also have some refractive power in the first plane of symmetry, i.e. the Y-Z plane, which, however, usually will be smaller than the primary refractive power in the second plane of symmetry, i.e. the X-Z plane.

In the embodiment shown in figures 2 and 3, the first and third lens arrangement 130, 150 may have the focal length F in the first plane of symmetry, i.e. the Y-Z plane, while the second lens arrangement 140 has substantially the focal length 2F in the second plane of symmetry, i.e. the X-Z plane. Moreover, in the embodiment shown in figures 2 and 3, the distance D between the first SLM 120 and the second SLM 160 may be four times the focal length F, i.e. D = 4F, wherein the first lens arrangement 130 is located at a distance F from the first SLM 120 and at a distance 3F from the second SLM 160, the second lens arrangement 140 is located at a distance 2F from the first SLM 120 and at a distance 2F from the second SLM 160, and the third lens arrangement 130 is located at a distance 3F from the first SLM 120 and at a distance F from the second SLM 160.

Figure 4 shows a flow diagram illustrating steps of a method 400 for selective wavelength switching of light by an optical apparatus 100 according to an embodiment. The method 400 comprises the steps 401 of receiving and redirecting a first plurality of demultiplexed light waveband channels by a first area 120a of a SLM 120, wherein the first SLM 120 further comprises a second area 120b. Moreover, the method 400 comprises the steps 403 of receiving and redirecting by a second area 160b of a second SLM 160 the first plurality of demultiplexed light waveband channels from the first area 120a of the first SLM 120 to the second area 120b of the first SLM 120, wherein the second SLM 160 is positioned along an optical axis OA at a distance D from the first SLM 120 and further comprises a first area 160a. The method 400 further comprises the steps 405a of receiving and redirecting, by a plurality of lens arrangements 130, 140, 150 positioned between the first SLM 120 and the second SLM 160, the first plurality of demultiplexed light waveband channels from the first area 120a of the first SLM 120 towards the second area 160b of the second SLM 160. Moreover, the method 400 comprises the steps of receiving and redirecting, by the plurality of lens arrangements 130, 140, 150 positioned between the first SLM 120 and the second SLM 160, the first plurality of demultiplexed light waveband channels from the second area 160b of the second SLM 160 towards the second area 120b of the first SLM 120. As illustrated in figure 4, the steps 405a and 405b may be performed substantially in parallel.

The person skilled in the art will understand that the "blocks" ("units") of the various figures (method and apparatus) represent or describe functionalities of embodiments of the present disclosure (rather than necessarily individual "units" in hardware or software) and thus describe equally functions or features of apparatus embodiments as well as method embodiments (unit = step).

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described embodiment of an apparatus is merely exemplary. For example, the unit division is merely logical function division and may be another division in an actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented by using some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, functional units in the embodiments of the invention may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.

Claims

1. An optical apparatus (100) for selective wavelength switching of light, wherein the optical apparatus (100) comprises: a first spatial light modulator, SLM, (120), wherein the first SLM (120) comprises a first area (120a) and a second area (120b) and wherein the first area (120a) of the first SLM (120) is configured to receive and redirect a first plurality of demultiplexed light waveband channels; a second SLM (160) positioned along an optical axis (OA) at a distance D from the first SLM (120), wherein the second SLM (160) comprises a first area (160a) and a second area (160b) and wherein the second area (160b) of the second SLM (160) is configured to receive and redirect the first plurality of demultiplexed light waveband channels from the first area (120a) of the first SLM (120) to the second area (120b) of the first SLM (120); a plurality of lens arrangements (130, 140, 150) positioned between the first SLM (120) and the second SLM (160) to receive and redirect the first plurality of demultiplexed light waveband channels from the first area (120a) of the first SLM (120) towards the second area (160b) of the second SLM (160) and to receive and redirect the first plurality of demultiplexed light waveband channels from the second area (160b) of the second SLM (160) towards the second area (120b) of the first SLM (120).

2. The optical apparatus (100) of claim 1 , wherein the first area (160a) of the second SLM (160) is configured to receive and redirect a second plurality of demultiplexed light waveband channels, wherein the second area (120b) of the first SLM (120) is configured to receive and redirect the second plurality of demultiplexed light waveband channels from the first area (160a) of the second SLM (160) to the second area (160b) of the second SLM (160), and wherein the plurality of lens arrangements (130, 140, 150) are configured to receive and redirect the second plurality of demultiplexed light waveband channels from the first area (160a) of the second SLM (160) towards the second area (120b) of the first SLM (120) and to receive and redirect the second plurality of demultiplexed light waveband channels from the second area (120b) of the first SLM (120) towards the second area (160b) of the second SLM (160).

3. The optical apparatus (100) of claim 1 or 2, wherein the first SLM (120) and the second SLM (160) have a substantially rectangular spatially extended portion, wherein the first area (120a) and the second area (120b) of the first SLM (120) are defined by a first half and a second half of the rectangular extended portion of the first SLM (120) and wherein the first area and the second area of the second SLM (160) are defined by a first half and a second half of the rectangular spatially extended portion of the second SLM (160).

4. The optical apparatus (100) of any one of the preceding claims, wherein the optical axis (OA) defines a first plane of symmetry and a second plane of symmetry perpendicular to the first plane of symmetry of the optical apparatus (100), wherein the first area (120a) of the first SLM (120) and the first area (160a) of the second SLM (160) are positioned on one side of the first plane of symmetry and the second area (120b) of the first SLM (120) and the second area (160b) of the second SLM (160) are positioned on an opposite side of the first plane of symmetry.

5. The optical apparatus (100) of claim 4, wherein the plurality of lens arrangements (130, 140, 150) comprise: a first lens arrangement (130) with a refractive power primarily in the first plane of symmetry; a second lens arrangement (140) with a refractive power primarily in the second plane of symmetry, wherein the second lens arrangement (140) is positioned between the first lens arrangement and the second SLM (160); and a third lens arrangement (150) having a refractive power primarily in the first plane of symmetry and positioned between the second lens arrangement (140) and the second SLM (160).

6. The optical apparatus (100) of claim 5, wherein the first lens arrangement (130), the second lens arrangement (140) and/or the third lens arrangement (150) comprises one or more cylindrical lenses.

7. The optical apparatus (100) of any one of the preceding claims, wherein the first SLM (120) and/or the second SLM (160) comprises a liquid crystal on silicon device and/or a digital mirror device.

8. The optical apparatus (100) of any one of the preceding claims, wherein the optical apparatus (100) further comprises a first dispersive optical element (110a,b) configured to disperse one or more first light beams into the first plurality of light waveband channels and to direct the first plurality of light waveband channels onto the first area (120a) of the first SLM (120) and/or to receive the first plurality of light waveband channels from the second area (120b) of the first SLM (120) and combine the first plurality of light waveband channels from the second area (120b) of the first SLM (120) into one or more first output light beams.

9. The optical apparatus (100) of any one of the preceding claims, wherein the optical apparatus (100) further comprises a second dispersive optical element (170a,b) configured to disperse one or more second light beams into the second plurality of light waveband channels and to direct the second plurality of light waveband channels onto the first area (160a) of the second SLM (160) and/or to receive the second plurality of light waveband channels from the second area (160b) of the second SLM (160) and combine the second plurality of light waveband channels from the second area (160b) of the second SLM (160) into one or more second output light beams.

10. The optical apparatus (100) of claim 8 or 9, wherein the first dispersive optical element (110a,b) and/or the second dispersive optical element (170a, b) comprises a grating, a prism and/or a grism.

11 . The optical apparatus (100) of any one of the preceding claims, wherein the plurality of lens arrangements (130, 140, 150) between the first SLM (120) and the second SLM (160) define an anamorphic optical system.

12. The optical apparatus (100) of any one of the preceding claims, wherein the plurality of lens arrangements (130, 140, 150) between the first SLM (120) and the second SLM (160) define an afocal optical system in one of the planes of symmetry.

13. A method (400) for selective wavelength switching of light by an optical apparatus (100), wherein the method (400) comprises: receiving and redirecting (401) a first plurality of demultiplexed light waveband channels by a first area (120a) of a first spatial light modulator, SLM, (120), wherein the first SLM (120) further comprises a second area (120b); receiving and redirecting (403) by a second area (160b) of a second SLM (160) the first plurality of demultiplexed light waveband channels from the first area (120a) of the first SLM (120) to the second area (120b) of the first SLM (120), wherein the second SLM (160) is positioned along an optical axis (OA) at a distance D from the first SLM (120) and further comprises a first area (160a); receiving and redirecting (405a), by a plurality of lens arrangements (130, 140, 150) positioned between the first SLM (120) and the second SLM (160), the first plurality of demultiplexed light waveband channels from the first area (120a) of the first SLM (120) towards the second area (160b) of the second SLM (160); and receiving and redirecting (405b), by the plurality of lens arrangements (130, 140, 150) positioned between the first SLM (120) and the second SLM (160), the first plurality of demultiplexed light waveband channels from the second area (160b) of the second SLM (160) towards the second area (120b) of the first SLM (120).