Wavelength division multiplexer

Abstract

A wavelength division multiplexer includes a prism, a collimator, and a filter bank. A collimator injects an optical input signal into an input surface of the prism. The filter bank is coupled to the prism. The filter bank includes a plurality of filters sequentially coupled to each other. Each filter reflects an optical input signal of a different wavelength and allows optical input signals of other wavelengths to pass to a next filter in the filter bank.

Description

Technical Field

[0001] This disclosure relates to multiplexers, and more particularly to wavelength division multiplexers. Background Technology

[0002] Conventional wavelength division multiplexers are large and cannot provide sufficiently fine optical spacing. Summary of the Invention

[0003] As shown and / or described in conjunction with at least one of the accompanying drawings, and more fully set forth in the claims, is a wavelength division multiplexer that provides a more laterally compact layout than conventional wavelength division multiplexers.

[0004] These and other advantages, aspects and novel features of this disclosure, as well as details of the embodiments shown therein, will be more fully understood from the following description and accompanying drawings. Attached Figure Description

[0005] The different features and advantages of this disclosure can be more readily understood by referring to the following detailed description taken in conjunction with the accompanying drawings, wherein the same reference numerals denote the same structural elements.

[0006] Figure 1 A first embodiment of a wavelength division multiplexer is described.

[0007] Figure 2 A second embodiment of a wavelength division multiplexer is described.

[0008] Figure 3 A third embodiment of a wavelength division multiplexer is described. Detailed Implementation

[0009] The following discussion provides various examples of wavelength division multiplexers that can provide a more laterally compact layout than conventional wavelength division multiplexers. These examples are non-limiting, and the scope of the appended claims should not be limited to the specific examples disclosed. In the following discussion, the terms "example" and "for example" are non-limiting.

[0010] The accompanying drawings illustrate a general configuration of the structure, and descriptions and details of known features and techniques may be omitted to avoid unnecessarily obscuring this disclosure. Furthermore, elements in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements in the drawings may be enlarged relative to other elements to aid in understanding the examples discussed in this disclosure. The same reference numerals in different drawings denote the same elements.

[0011] The term "and / or" means any one or more of the terms connected by "and / or" in the list. For example, "x and / or y" means any element in the ternary set {(x), (y), (x, y)}. As another example, "x, y and / or z" means any element in the heptagonal set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}.

[0012] The terms “comprises”, “comprising”, “includes”, and / or “including” are “open-ended” terms and specify the presence of the stated feature, but do not exclude the presence or addition of one or more other features.

[0013] The terms “first,” “second,” etc., may be used herein to describe different elements, and these elements are not limited by these terms. These terms are used only to distinguish one element from another. Thus, for example, without departing from the teachings of this disclosure, the first element discussed herein may be referred to as the second element.

[0014] Unless otherwise specified, the term "coupled" can be used to describe two elements that are in direct contact with each other or to describe two elements that are indirectly connected through one or more other elements. For example, if element A is coupled to element B, then element A can either be in direct contact with element B or be indirectly connected to element B through intervening element C. Similarly, the terms "above" or "on" can be used to describe two elements that are in direct contact with each other or to describe two elements that are indirectly connected through one or more other elements.

[0015] Now for reference Figure 1 This illustrates a wavelength division multiplexer 100. Specifically, Figure 1 The wavelength division multiplexer 100 may include a collimator 110, a prism 120, and a filter bank 130. The collimator 110 may receive an optical input signal S from a light source (e.g., multimode fiber) incident on the collimator 110. The collimator 110 may further inject the received optical input signal S into the prism 120.

[0016] Prism 120 may include a block of glass or other dielectric material defining a lower prism surface 121, a prism input surface 122, a prism upper surface 123, and a prism output surface 124. As depicted, the prism output surface 124 may be positioned laterally opposite and parallel to the prism input surface 122. The lower prism surface 121 and the upper prism surface 123 may be located between the prism input surface 122 and the prism output surface 124. In some embodiments, the upper prism surface 123 may be positioned perpendicularly opposite and parallel to the lower prism surface 121.

[0017] The prism input surface 122 may include an input portion 125 through which the collimator 110 injects an optical input signal S into the prism 120. The prism input surface 122 may also include a reflective portion 126 coated with a reflective film 127. The reflective film 127 along the prism input surface 122 may reflect the optical input signal S and its associated wavelength toward the prism output surface 124. In different embodiments, the input portion 125 is not coated with the reflective film 127.

[0018] The filter bank 130 may include a first filter 130a, a second filter 130b, a third filter 130c, and a fourth filter 130d along the prism output surface 124. Specifically, the first filter 130a may be positioned laterally opposite the input portion 125 of the prism input surface 122. Thus, the optical input signal S can laterally pass through the prism 120 from the input portion 125 of the prism input surface 122 to reach the first filter 130a. Further, the second filter 130b may be positioned above the first filter 130a and offset from the first filter 130a by a first offset distance, the third filter 130c may be positioned above the second filter 130b and offset from the second filter 130b by a second offset distance, and the fourth filter 130d may be positioned above the third filter 130c and offset from the third filter 130c by a third offset distance. In some embodiments, filters 130a-130d may be offset from each other by the same offset distance along the prism output surface 124. Furthermore, the segmented optical output signal D can be separated from filters 130a-130d, thus giving the segmented wavelength signals a signal spacing equal to the offset of filters 130a-130c (i.e., the distance between the segmented wavelength signals).

[0019] The first filter 130a and / or the prism output surface 124 of prism 120 can provide a first passband that allows an optical input signal S of a first wavelength λa to pass through the prism output surface 124 and exit the first filter 130a as a first segmented wavelength signal λa of the segmented optical output signal D. The first filter 130a and / or the prism output surface 124 of prism 120 can reflect optical input signals S of other wavelengths (e.g., wavelengths λb, λc, and λd) back to the reflective portion 126 of the prism input surface 122. The reflective film 127 along the reflective portion 126 of the prism input surface 122 can reflect the optical input signals S, including wavelengths λb, λc, and λd received from the first filter 130a, toward the second filter 130b.

[0020] The second filter 130b and / or the prism output surface 124 of prism 120 can provide a second passband that allows the optical input signal S of the second wavelength λb to pass through the prism output surface 124 and exit the second filter 130b as a second segmented wavelength signal λb of the segmented optical output signal D. Specifically, the optical input signal S of the second wavelength λb can be parallel to the optical input signal S of the first wavelength λa and offset from the optical input signal S of the first wavelength λa by a first offset distance between filters 130a and 130b, thereby exiting the second filter 130b. Furthermore, the second filter 130b and / or the prism output surface 124 of prism 120 can reflect optical input signals S of other wavelengths (e.g., wavelengths λc and λd) back to the reflective portion 126 of the prism input surface 122. The reflective film 127 along the reflective portion 126 of the prism input surface 122 can reflect the optical input signals S including wavelengths λc and λd received from the second filter 130b toward the third filter 130c.

[0021] The third filter 130c and / or prism output surface 124 of prism 120 can provide a third passband that allows a third wavelength λc optical input signal S to pass through prism output surface 124 and exit the third filter 130c as a third segmented wavelength signal λc of the segmented optical output signal D. Specifically, the third wavelength λc optical input signal S can be parallel to the second wavelength λb optical input signal S and offset from the second wavelength λb optical input signal S by a second offset distance between filters 130b and 130c, thereby exiting the third filter 130c. Furthermore, the third filter 130c and / or prism output surface 124 of prism 120 can reflect optical input signals S of other wavelengths (e.g., wavelength λd) back to the reflective portion 126 of prism input surface 122. The reflective film 127 along the reflective portion 126 of prism input surface 122 can reflect the optical input signal S including wavelength λd received from the third filter 130c toward the fourth filter 130d.

[0022] The fourth filter 130d and / or the prism output surface 124 of the prism 120 can provide a fourth passband that allows the optical input signal S with a fourth wavelength λd to pass through the prism output surface 124 and exit the fourth filter 130d as a fourth segmented wavelength signal λd of the segmented optical output signal D. Specifically, the optical input signal S with the fourth wavelength λd can be parallel to the optical input signal S with a third wavelength λc and exit the fourth filter 130d by a third offset distance from the optical input signal S with a second wavelength λc between the third filter 130c and the fourth filter 130d.

[0023] Although Figure 1A wavelength division multiplexer 100 is described, which utilizes four filters 130a-130d to divide an optical input signal S and outputs a divided optical output signal D comprising four divided wavelength signals λa, λb, λc, and λd. However, the wavelength division multiplexer 100 may include a different number of filters 130a-130d that divide the optical input signal S into corresponding numbers of wavelength signals.

[0024] In addition, although Figure 1 The wavelength division multiplexer 100 can effectively divide the optical input signal S into a corresponding number of wavelength signals, but the wavelength division multiplexer 100 positions the collimator 110 and the light source (e.g., incident optical fiber) laterally inlined with the prism 120 and the filter bank 130. This laterally inlined positioning can consume more lateral space than is desired for some applications.

[0025] Figure 2 Another wavelength division multiplexer 200 is described, which in some embodiments is more advanced than... Figure 1 The wavelength division multiplexer 100 consumes less lateral space. With Figure 1 Similar to the wavelength division multiplexer 100, Figure 2 The wavelength division multiplexer 200 includes a collimator 210, a prism 220, and a filter bank 230. However, unlike... Figure 1 The wavelength division multiplexer 100, collimator 210, and filter bank 230 are arranged longitudinally. Furthermore, the collimator 210 and filter bank 230 are positioned on the same side of the prism 220. In this way, the collimator 210 can laterally overlap with the filter bank 230. Therefore, the wavelength division multiplexer 200 can be implemented in a more laterally compact manner than the wavelength division multiplexer 100.

[0026] For this purpose, collimator 210 can receive the optical input signal S from the light source (e.g., multimode fiber) incident on collimator 210. Collimator 210 can further inject the received optical input signal S into prism 220.

[0027] Prism 220 may include a block of glass or other dielectric material defining a lower prism surface 221, a prism input surface 222, a prism upper surface 223, and a prism output surface 224. As depicted, the prism output surface 224 may be positioned laterally opposite and parallel to the prism input surface 222. The lower prism surface 221 and the upper prism surface 223 may be located between the prism input surface 222 and the prism output surface 224. In some embodiments, the upper prism surface 223 may be positioned perpendicularly opposite and parallel to the lower prism surface 221.

[0028] The prism input surface 222 may include an input portion 225 and a filter interface portion 226. A collimator 210 may inject an input light signal S into the prism 220 via the input portion 225. An antireflective coating 242 may be coated or otherwise positioned along the input portion 225 of the prism input surface 222. The filter interface portion 226 of the prism input surface 222 may be uncoated and / or polished to provide an interface to the filter bank 230 extending from the prism input surface 222. A reflective coating 227 may be coated or otherwise positioned along the reflective portion 228 of the prism output surface 224. An antireflective coating 244 may be coated or otherwise positioned along the output portion 229 of the prism output surface 224. In some embodiments, the lower prism surface 221 and the upper prism surface 223 may be frosted.

[0029] In various embodiments, prism 220 can be implemented as a glass parallelepiped. In such an embodiment, the prism input surface 222 and the prism upper surface 223 can form an acute angle ranging from 72° to 82°. Furthermore, antireflective coatings 242 and 244 can be formed using electron beam evaporation coating technology to obtain reflectivity. The antireflective coating is suitable for wavelengths between approximately 1240 nm and 1360 nm and incident angles (AOI) between approximately 8° and 18°. Similarly, electron beam evaporation deposition technology can be used to form reflective films to obtain reflective properties. The reflective coating is suitable for wavelengths between approximately 1240 nm and 1360 nm and incident angles (AOI) between approximately 5.31° and 6.14°.

[0030] Filter bank 230 may include a first filter 230a, a second filter 230b, a third filter 230c, and a fourth filter 230d. Filter bank 230 can segment and spatially separate the optical input signal S into multiple wavelength signals (e.g., wavelength signals λa, λb, λc, and λd). Furthermore, filter bank 230 can reflect or otherwise guide the spatially separated wavelength signals out of the output portion 229 of the prism output surface 224. For this purpose, filter bank 230 may include a first filter 230a, a second filter 230b, a third filter 230c, and a fourth filter 230d. The four filters 230a-230d of the filter bank can provide four reflective bandpass filters that are stacked and coupled to each other using a bonding material such as ultraviolet (UV) adhesive.

[0031] The first filter 230 may include a first filter input surface 232a coupled to a filter interface portion 226 of the prism input surface 222 and a first filter output surface 234a laterally opposite the first filter input surface 232a. Furthermore, the first filter input surface 232a may be coated with a reflective coating that reflects light centered at a first wavelength λa (e.g., 1271 nm) of the optical input signal and exits the prism output surface 224 as a segmented optical output signal D with a first wavelength signal λa. Additionally, the reflective coating along the first filter input surface 232a may allow optical input signals S of other wavelengths (e.g., wavelengths λb, λc, and λd) to pass through the first filter 230a and reach the first filter output surface 234a. In various embodiments, the first filter output surface 234a is uncoated and / or polished to facilitate the transmission of optical input signals S of other wavelengths to the second filter 230b.

[0032] The second filter 230b may include a second filter input surface 232b coupled to the first filter output surface 234a and a second filter output surface 234b laterally opposite to the second filter input surface. Furthermore, the second filter input surface 232b is coated with a reflective coating that reflects light centered at the second wavelength λb (e.g., 1291 nm) of the optical input signal and exits the output portion 229 of the prism 220 as a segmented optical output signal D with a second wavelength signal λb. Additionally, the reflective coating along the second filter input surface 232b allows optical input signals S of other wavelengths (e.g., wavelengths λc and λd) to pass through the second filter 230b and reach the second filter output surface 234b. In various embodiments, the second filter output surface 234b is uncoated and / or polished to facilitate the transmission of optical input signals S of other wavelengths to the third filter 230c.

[0033] The third filter 230c may include a third filter input surface 232c coupled to the output surface 234b of the second filter and a third filter output surface 234c laterally opposite to the input surface 232c. Furthermore, the third filter input surface 232c is coated with a reflective coating that reflects light centered at a third wavelength λc (e.g., 1311 nm) of the optical input signal S and exits the output portion 229 of the prism 220 as a segmented optical output signal D with the third wavelength signal λc. Additionally, the reflective coating along the third filter input surface 232c allows optical input signals S of other wavelengths (e.g., wavelength λd) to pass through the third filter 230c and reach the third filter output surface 234c. In various embodiments, the third filter output surface 234c may be uncoated and / or polished to facilitate the transmission of optical input signals S of other wavelengths (e.g., wavelength λd) to the fourth filter 230d.

[0034] The fourth filter 230d may include a fourth filter input surface 232d coupled to the third filter output surface 234c and a fourth filter output surface 234d laterally opposite to the fourth filter input surface 232d. Furthermore, the fourth filter input surface 232d is coated with a reflective coating that reflects light centered on the fourth wavelength λd (e.g., 1331 nm) of the optical input signal S and exits the output portion 229 of the prism 220 as a segmented optical output signal D with the fourth wavelength signal λd. Additionally, the reflective coating along the fourth filter input surface 232d allows optical input signals S of other wavelengths to pass through the fourth filter 230d and reach the fourth filter output surface 234d. In various embodiments, the fourth filter output surface 234d may be uncoated and / or polished to facilitate the passage of optical input signals S of other wavelengths through the fourth filter output surface 234d.

[0035] In some embodiments, the first filter 230a, the second filter 230b, the third filter 230c, and the fourth filter 230d can be implemented using a WMS-15 glass-ceramic substrate purchased from Ohara Corp. Such a substrate can be sequentially coated with a high-refractive-index film and a low-refractive-index film to provide a bandpass reflective film structure. In some embodiments, the substrates of filters 230a-230d can be coated using magnetron sputtering with high-refractive-index and low-refractive-index film materials. Furthermore, in some embodiments, the high-refractive-index material can be implemented using tantalum pentoxide (Ta₂O₅) with a refractive index of approximately 2.13, and the low-refractive-index film material can be implemented using silicon dioxide (SiO₂) with a refractive index of approximately 1.46.

[0036] Due to the arrangement of prism 220 and filter bank 230, wavelength division multiplexer 200 can provide a shorter optical path between the input and output of wavelength division multiplexer 100 compared to wavelength division multiplexer 100. As a result of this reduced optical path, it is compatible with devices such as... Figure 1 Compared to other reflection-type wavelength division multiplexers, wavelength division multiplexer 200 can provide smaller spacing (i.e., smaller offset between) of the divided wavelengths λa, λb, λc, and λd output from prism 220. Furthermore, such an arrangement allows for compatibility with other wavelength division multiplexers, such as... Figure 1 The wavelength division multiplexer 100 is implemented in a more laterally compact manner compared to other reflection-type wavelength division multiplexers 200.

[0037] Figure 2 A wavelength division multiplexer 200 is depicted, utilizing four filters 230a-230d to divide an optical input signal S into four segmented wavelength signals λa, λb, λc, and λd. However, in some embodiments, the wavelength division multiplexer 200 may include a different number of filters 230a-230d that divide the optical input signal S into corresponding numbers of wavelength signals.

[0038] Figure 3 A wavelength division multiplexer 300 is described, which in some embodiments is more... Figure 1 The wavelength division multiplexer 100 consumes less lateral space. With Figure 1 Similar to the wavelength division multiplexer 100, Figure 3 The wavelength division multiplexer 300 includes a collimator 310, a prism 320, and a filter bank 330. However, unlike... Figure 1 In the wavelength division multiplexer 100, the split light is output from a prism lower output surface 321 in prism 320, which is adjacent to the prism-side input surface 322. In the depicted embodiment, the prism lower output surface 321 is coupled to the prism-side input surface 322 at a 90° angle, thereby producing a split light output signal D that exits the prism 320 at a 90° angle relative to the light input signal S injected into the prism 320. However, other embodiments of the wavelength division multiplexer 300 can abut the prism lower output surface 321 to the prism-side input surface 322 at other angles (e.g., any angle between 60° and 120°). Regarding the spatial separation between the input and output of the prism 320, this orientation of the prism lower output surface 321 to the prism-side input surface 322 allows the wavelength division multiplexer 300 to be implemented in a more laterally compact manner than the wavelength division multiplexer 100.

[0039] For this purpose, collimator 310 can receive the optical input signal S from the light source (e.g., multimode fiber) incident on collimator 310. Collimator 310 can further inject the received optical input signal S into prism 320.

[0040] The prism 320 may include a block of glass or other dielectric material defining a lower prism output surface 321, a prism-side input surface 322, a prism upper surface 323, and a prism-side surface 324. As depicted, the prism-side surface 324 may be positioned laterally opposite the prism-side input surface 322 and angled toward the prism upper surface 323 to reflect the light input signal S. The lower prism output surface 321 and the prism upper surface 323 may be located between the prism-side input surface 322 and the prism-side surface 324. In some embodiments, the prism upper surface 323 may be vertically positioned above the lower prism output surface 321 and angled relative to the prism-side surface 324 to reflect signals from the prism-side surface 324 out of the lower prism output surface 321.

[0041] The prism-side input surface 322 may include an input portion 325. A collimator 310 may inject an optical input signal S into the prism 320 through the input portion 325. An antireflective coating 342 may be coated or otherwise positioned along the input portion 325 of the prism-side input surface 322. The prism-side surface 324 may include a filter interface portion 326. The filter interface portion 326 may be uncoated and / or polished to provide an interface to a filter bank 330 extending from the prism-side surface 324. A reflective coating 327 may be coated or otherwise positioned along the reflective portion 328 of the upper prism surface 323. An antireflective coating 344 may be coated or otherwise positioned along the output portion 329 of the lower prism output surface 321.

[0042] In various embodiments, the prism 320 can be implemented using a glass block or other dielectric material. Furthermore, electron beam evaporation deposition technology can be used to form antireflective coatings 342 and 344 to obtain reflective properties. The anti-reflective coating is suitable for wavelengths between approximately 1240 nm and 1360 nm. Similarly, electron beam evaporation deposition technology can be used to form reflective films to obtain reflective properties. The reflective coating is suitable for wavelengths between approximately 1240 nanometers and 1360 nanometers.

[0043] Filter bank 330 can segment and spatially separate the optical input signal S into multiple wavelength signals (e.g., wavelength signals λa, λb, λc, and λd). Furthermore, filter bank 330 can reflect or otherwise guide the spatially separated wavelength signals toward the reflective portion 328 of the upper surface 323 of the prism. For this purpose, filter bank 330 may include a first filter 330a, a second filter 330b, a third filter 330c, and a fourth filter 330d. The four filters 330a-330d of filter bank 330 can provide four reflective bandpass filters that are stacked and coupled to each other using a bonding material such as ultraviolet (UV) adhesive.

[0044] The first filter 330a may include a first filter input surface 332a coupled to a filter interface portion 326 of a prism side surface 324 and a first filter output surface 334a laterally opposite the first filter input surface 332a. Furthermore, the first filter input surface 332a may be coated with a reflective coating that reflects light centered on a first wavelength λa (e.g., 1271 nm) of the light input signal along the upper surface 323 of the prism towards a reflective film 327. The upper surface 323 of the prism may sequentially reflect the first wavelength λa as a first wavelength signal λa of a segmented light output signal D out of the output portion 329 of the lower output surface 321 of the prism. Additionally, the reflective coating along the first filter input surface 332a may allow light input signals S of other wavelengths (e.g., wavelengths λb, λc, and λd) to pass through the first filter 330a and reach the first filter output surface 334a. In various embodiments, the first filter output surface 334a is uncoated and / or polished to facilitate the transmission of light input signals S of other wavelengths to the second filter 330b.

[0045] The second filter 330b may include a second filter input surface 332b coupled to the first filter output surface 334a and a second filter output surface 334b ​​laterally opposite to the second filter input surface 332b. Furthermore, the second filter input surface 332b may be coated with a reflective coating that reflects light centered on the second wavelength λb (e.g., 1291 nm) of the optical input signal S along the upper prism surface 323 toward the reflective film 327. The upper prism surface 323 may, in turn, reflect the second wavelength λb as a second wavelength signal λb of the segmented optical output signal D out of the output portion 329 of the lower prism output surface 321. Additionally, the reflective coating along the second filter input surface 332b may allow optical input signals of other wavelengths (e.g., wavelengths λc and λd) to pass through the second filter 330b and reach the second filter output surface 334b. In various embodiments, the second filter output surface 334b ​​is uncoated and / or polished to facilitate the transmission of optical input signals S of other wavelengths to the third filter 330c.

[0046] The third filter 330c may include a third filter input surface 332c coupled to the output surface 334b ​​of the second filter and a third filter output surface 334c laterally opposite to the input surface 332c. Furthermore, the third filter input surface 332c may be coated with a reflective coating that reflects light centered at a third wavelength λc (e.g., 1311 nm) of the optical input signal S along the upper surface 323 of the prism towards the reflective film 327. The upper surface 323 of the prism may subsequently reflect the third wavelength λc as the third wavelength signal λc of the segmented optical output signal D out of the output portion 329 of the lower output surface 321 of the prism. Additionally, the reflective coating along the third filter input surface 332c may allow optical input signals S of other wavelengths (e.g., wavelength λd) to pass through the third filter 330c and reach the third filter output surface 334c. In various embodiments, the third filter output surface 334c may be uncoated and / or polished to facilitate the transmission of optical input signals S of other wavelengths (e.g., wavelength λd) to the fourth filter 330d.

[0047] The fourth filter 330d may include a fourth filter input surface 332d coupled to the third filter output surface 334c and a fourth filter output surface 334d laterally opposite to the fourth filter input surface 332d. Furthermore, the fourth filter input surface 332d may be coated with a reflective coating that reflects light centered on the fourth wavelength λd (e.g., 1331 nm) of the optical input signal S along the upper prism surface 323 toward the reflective film 327. The upper prism surface 323 may subsequently reflect the fourth wavelength λd as the fourth wavelength signal λd of the segmented optical output signal D out of the output portion 329 of the lower prism output surface 321. Additionally, the reflective coating along the fourth filter input surface 332d may allow other wavelengths of optical input signals S to pass through the fourth filter 330d and reach the fourth filter output surface 334d. In various embodiments, the fourth filter output surface 334d may be uncoated and / or polished to facilitate the passage of other wavelengths of optical input signals S through the fourth filter output surface 334d.

[0048] In some embodiments, the first filter 330a, the second filter 330b, the third filter 330c, and the fourth filter 330d can be implemented using a WMS-15 glass-ceramic substrate purchased from Ohara Corp. Such a substrate can be sequentially coated with a high-refractive-index film and a low-refractive-index film to provide a bandpass reflective film structure. In some embodiments, the substrates of filters 330a-330d can be coated using magnetron sputtering with high-refractive-index and low-refractive-index film materials. Furthermore, in some embodiments, the high-refractive-index material can be implemented using tantalum pentoxide (Ta₂O₅) with a refractive index of approximately 2.13, and the low-refractive-index film material can be implemented using silicon dioxide (SiO₂) with a refractive index of approximately 1.46.

[0049] Due to the arrangement of the prism 320 and the filter bank 330, the wavelength division multiplexer 300 can provide a shorter optical path between the input and output of the wavelength division multiplexer 100 compared to the wavelength division multiplexer 100. As a result of this reduced optical path, it is compatible with devices such as... Figure 1 Compared to other reflection-type wavelength division multiplexers, wavelength division multiplexer 300 can provide smaller spacing (i.e., smaller offset between) of the divided wavelengths λa, λb, λc, and λd output from prism 320. Furthermore, such an arrangement allows for compatibility with other wavelength division multiplexers, such as... Figure 1 The wavelength division multiplexer 100 is implemented in a more laterally compact manner compared to other reflection-type wavelength division multiplexers, such as wavelength division multiplexer 300.

[0050] Figure 3A wavelength division multiplexer 300 is depicted, utilizing four filters 330a-330d to divide an optical input signal S into four segmented wavelength signals λa, λb, λc, and λd. However, in some embodiments, the wavelength division multiplexer 300 may include a different number of filters 330a-330d that divide the optical input signal S into corresponding numbers of wavelength signals.

[0051] This disclosure includes references to certain examples; however, those skilled in the art will understand that various changes can be made and equivalents can be substituted without departing from the scope of this disclosure. Furthermore, modifications can be made to the disclosed examples without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the disclosed examples, but rather to include all examples falling within the scope of the appended claims.

Claims

1. A wavelength division multiplexer comprising: a prism comprising a prism input surface and a prism output surface, wherein the prism input surface comprises an input portion configured to receive an optical input signal, and wherein the prism output surface comprises an output portion configured to output a split optical output signal comprising a plurality of wavelength optical signals separated in space by a pitch; and a filter set coupled to a filter interface portion of the prism, wherein the filter set comprises a plurality of filters coupled in sequence to one another, wherein each of the filters reflects a different wavelength of the split optical output signal and allows other wavelengths to pass to a next filter in the plurality of filters.

2. The wavelength division multiplexer of claim 1, wherein: the prism output surface is laterally opposed to the prism input surface; the prism input surface comprises the filter interface portion of the prism; the prism output surface comprises an output portion and a reflective portion; the reflective portion reflects the optical input signal toward the filter set; and the filter set splits the optical input signal into a plurality of wavelength signals and reflects the plurality of wavelength signals out of the output portion of the prism output surface.

3. The wavelength division multiplexer of claim 2, wherein, the prism output surface is parallel to the prism input surface.

4. The wavelength division multiplexer of claim 2, wherein, the reflective portion of the prism output surface comprises a reflective film.

5. The wavelength division multiplexer of claim 2, wherein, the output portion of the prism output surface comprises an anti-reflective film.

6. The wavelength division multiplexer of claim 2 wherein, the input portion of the prism input surface comprises an anti-reflective film.

7. The wavelength division multiplexer of claim 1, wherein: a first filter of the filter set comprises a first filter input surface and a first filter output surface opposed to the first filter input surface; the first filter input surface is coupled to the filter interface portion and comprises a first reflective coating that reflects light centered at a first wavelength of the optical input signal and allows other wavelengths of the optical input signal to pass through the first filter output surface; a second filter of the filter set comprises a second filter input surface and a second filter output surface opposed to the second filter input surface; and the second filter input surface is coupled to the first filter output surface and comprises a second reflective coating that reflects light centered at a second wavelength of the optical input signal and allows other wavelengths of the optical input signal to pass to the second filter output surface.

8. The wavelength division multiplexer of claim 1, wherein: the prism output surface abuts the prism input surface; the prism comprises a prism side surface opposed to the prism input surface; the prism side surface comprises the filter interface portion of the prism; the prism comprises an upper reflective portion opposed to the prism output surface; the filter set splits the optical input signal into a plurality of wavelength signals and reflects the plurality of wavelength signals toward the upper reflective portion; and the upper reflective portion of the prism reflects the plurality of wavelength signals out of the prism output surface.

9. The wavelength division multiplexer of claim 8, wherein, the prism output surface and the prism input surface abut at a 90° angle.

10. The wavelength division multiplexer of claim 8, wherein, The prism output surface and the prism input surface adjoin at an angle between 60° and 120°.

11. The wavelength division multiplexer of claim 8, wherein, The upper reflective portion includes a reflective film.

12. The wavelength division multiplexer of claim 8, wherein, The output portion of the prism output surface includes an anti-reflective film.

13. The wavelength division multiplexer of claim 8, wherein, The input portion of the prism input surface includes an anti-reflective film.

14. The wavelength division multiplexer of claim 1, comprising a collimator configured to inject the optical input signal into the prism via the prism input surface.

15. A wavelength division multiplexer, comprising: a prism; a collimator configured to inject an optical input signal into an input surface of the prism; and a filter set coupled to the prism, wherein the filter set comprises a plurality of filters coupled to one another in series, wherein each filter reflects a different wavelength of the optical input signal and allows other wavelengths of the optical input signal to pass to a next filter of the filter set.

16. The wavelength division multiplexer of claim 15, wherein: an output surface of the prism is laterally opposite the input surface of the prism; the filter set is coupled to the input surface of the prism; a reflective portion of the prism reflects the optical input signal toward the filter set; and the filter set splits the optical input signal into a plurality of wavelength signals and reflects the plurality of wavelength signals out of an output surface of the prism. an output surface of the prism is parallel to an input surface of the prism.

17. The wavelength division multiplexer of claim 16, wherein, 18. The wavelength division multiplexer of claim 16, wherein: the output surface of the prism comprises an output portion coated with an anti- reflective film, the plurality of wavelength signals exiting the prism through the output portion coated with an anti-reflective film; and the input surface of the prism comprises an input portion coated with an anti- reflective film, the optical input signal injected into the prism through the input portion coated with an anti-reflective film.

19. The wavelength division multiplexer of claim 15, wherein: a first filter of the filter set comprises a first filter input surface and a first filter output surface opposite the first filter input surface; the first filter input surface is coupled to the prism and comprises a first reflective coating that reflects light centered at a first wavelength of the optical input signal and allows other wavelengths of the optical input signal to pass through the first filter output surface; a second filter of the filter set comprises a second filter input surface and a second filter output surface opposite the second filter input surface; and the second filter input surface is coupled to the first filter output surface and comprises a second reflective coating that reflects light centered at a second wavelength of the optical input signal and allows other wavelengths of the optical input signal to pass to the second filter output surface.

20. The wavelength division multiplexer of claim 15, wherein: an output surface of the prism adjoins an input surface of the prism; a side of the prism is opposite the input surface; the filter set is coupled to the side of the prism, splits the optical input signal into a plurality of wavelength signals, and reflects the plurality of wavelength signals toward a reflective surface of the prism; and the filter set is coupled to the side of the prism, splits the optical input signal into a plurality of wavelength signals, and reflects the plurality of wavelength signals toward a reflective surface of the prism. And The reflective surface of the prism reflects the plurality of wavelength signals out of an output surface of the prism.

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