Beam expanding optical ferrule

Abstract

An optical ferrule (200) includes an input surface (10) to receive and transmit a central light ray (21) from an optical fiber (20) attached to the optical ferrule. A light redirecting side (30) receives the central light ray (21) transmitted by the input surface (10) along a first direction (40) and redirects the received light along a different second direction (41). The redirected central light ray (23) exits the optical ferrule through an output surface (50) of the optical ferrule. As the central light ray (21) propagates in the optical ferrule from the input surface (10) to the output surface (50), the central light ray (21) propagates through different first and second portions (60, 70) of the optical ferrule having different respective first and second components, respectively.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to optical coupling devices such as optical ferrules, and in particular to expanded beam optical ferrules. BACKGROUND

[0002] Optical communication is increasingly used in systems compared to electrical communication to enable data communication with greater bandwidth and / or lower electromagnetic interference. In some systems, optical and electrical communication can be used in interconnection. Optical fibers can be employed for optical input / output, and for some applications, optical fibers can be coupled to other optical fibers and / or system components by optical connectors. Optical connectors are used for optical communication in a variety of applications, including communication networks, local area networks, data center links, and internal links in computer devices. Optical connectors, including expanded beam optical connectors, can include an optical ferrule having elements for receiving and securing an optical waveguide, elements for affecting light from the optical waveguide, and features for aligning the optical ferrule with a mating optical ferrule. Injection molding of polymer materials used to make expanded beam fiber ferrules is a widely used, cost-effective method for mass production of fiber ferrules. SUMMARY

[0003] Various aspects and embodiments described herein relate to optical connectors and optical ferrules.

[0004] Some aspects of the present disclosure relate to an optical ferrule including an input surface for receiving and transmitting a central light ray from an optical fiber attached to the optical ferrule. A light redirecting side of the optical ferrule receives the central light ray transmitted by the input surface along a first direction and redirects the received light along a different second direction. The redirected central light ray exits the optical ferrule through an output surface of the optical ferrule. The central light ray propagates through different first and second portions of the optical ferrule when propagating in the optical ferrule from the input surface to the output surface, the different first and second portions having different respective first and second components, respectively.

[0005] Some other aspects of the present disclosure relate to an optical ferrule including a light input surface, a light redirecting surface, a light output surface, a glass portion, and a polymer portion, wherein the glass portion includes glass and at least one of the light input surface and the light output surface, and the polymer portion includes a polymer and is disposed between the glass portion and the light redirecting surface. The optical ferrule is configured such that light entering the optical ferrule through the light input surface exits the optical ferrule through the light output surface after being redirected by the light redirecting surface. The light propagates through the glass portion and the polymer portion of the optical ferrule when propagating from the light input surface to the light output surface.

[0006] Some other aspects of the present disclosure relate to an optical ferrule including a trench for receiving and supporting an optical waveguide. The trench includes opposite open front and back ends. A light redirecting member of the optical ferrule includes an input surface for receiving light from the optical waveguide received and supported in the trench. A light redirecting side of the light redirecting member changes a direction of the light received from the input surface. The open back end of the trench is disposed between the open front end of the trench and the input surface. The open back end of the trench and the input surface define a recessed region therebetween. An optically transparent glass insert is disposed in the recessed region and substantially conforms in shape to an interior shape of the recessed region.

[0007] Other aspects of the present disclosure relate to a hybrid optical ferrule including a light input surface, a light redirecting side, and a light output surface. A first ferrule portion has a first optical intensity damage threshold I1. A second ferrule portion has a second optical intensity damage threshold I2, where I2≤ I1 / 5. The hybrid optical ferrule is configured such that light entering the optical ferrule through the light input surface exits the optical ferrule through the light output surface after being redirected by the light redirecting surface and propagates through the first ferrule portion and the second ferrule portion. The light has maximum intensities Imax1 and Imax2 as it propagates through the respective first and second ferrule portions. The first and second ferrule portions are arranged such that Imax2 < I2 < Imax1 < I1.

[0008] Some other aspects of the present disclosure relate to an optical ferrule assembly including an optical ferrule according to one or more aspects of the present disclosure, and an optical waveguide received and supported in the trench.

[0009] These and other aspects of the application will become apparent from the detailed description below. In no way, however, should the above summary be understood to limit the claimed subject matter, which is defined solely by the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0010] Various aspects of the present disclosure will be discussed in greater detail with reference to the drawings, in which:

[0011] Figures 1 to 3 Different views of an optical ferrule according to certain embodiments are schematically illustrated;

[0012] Figure 4 A cross-sectional view of an optical ferrule according to one aspect of the present disclosure is schematically illustrated;

[0013] Figure 5 Light propagating through different first and second portions of an optical ferrule is schematically illustrated;

[0014] Figure 6An optical ferrule is schematically illustrated in accordance with some aspects of the present disclosure;

[0015] Figure 7 A partial view of an optical ferrule is schematically illustrated in accordance with some aspects of the present disclosure, showing an end facet of an optical waveguide and an input surface of the ferrule;

[0016] Figure 8 A cross-sectional view of an optical ferrule is schematically illustrated in accordance with some other aspects of the present disclosure;

[0017] Figure 9 A partial view of an optical ferrule is schematically illustrated in accordance with some aspects of the present disclosure;

[0018] Figures 10 to 12 Different cross-sectional views of an optical ferrule are schematically illustrated in accordance with some aspects of the present disclosure;

[0019] Figures 13 to 15 Different views of an optical ferrule assembly are schematically illustrated in accordance with some aspects of the present disclosure; and

[0020] Figure 16 A graphical representation of optical intensity of light entering an optical ferrule and propagating through different first and second ferrule portions is shown.

[0021] The drawings are not necessarily to scale. Like numbers indicate like parts throughout the drawings. It will be appreciated, however, that like numbers do not necessarily indicate identical parts throughout the several illustrative drawings. DETAILED DESCRIPTION

[0022] In the following description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration various embodiments. It is to be understood that other embodiments can be utilized and that structural or logical changes can be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

[0023] An expanded beam can be used in a connector to provide an optical connection that is less sensitive to dust and other forms of contamination, in order to relax alignment tolerances. Generally, an expanded beam is a beam of light having a diameter that is larger than the core of the associated optical waveguide, typically a fiber optic, such as a multi-mode fiber optic used in a multi-mode communication system. A connector is generally considered to be an expanded beam connector if there is an expanded beam at the point of connection. In certain examples, an expanded beam ferrule can include an expanded beam section (e.g., a GRIN fiber) for expanding the beam diameter of an optical signal passing through the expanded beam section. The expanded beam is obtained by divergence of the beam of light from a light source or fiber optic. In many cases, the divergent beam is processed by an optical element such as a lens or mirror into an approximately collimated expanded beam. The expanded beam is then received via another lens or mirror that focuses the beam.

[0024] Injection molding of a polymer material is a widely used, cost-effective method for manufacturing expanded beam fiber ferrules. Due to the high power density from the optical fiber, particularly single mode optical fibers, the polymer material can experience photodegradation, which can negatively impact the performance of the connector. The light beam emitted from the optical fiber diverges in the ferrule material, and the area in front of the fiber facet has the highest power density, which experiences the highest degradation. The embodiments described herein address these and other challenges.

[0025] Some embodiments of the present disclosure relate to optical ferrules including a plate made of a suitable material that can handle the high power density light in the area of the ferrule with the highest power density (e.g., the area in front of the fiber facet) to reduce or eliminate photodegradation.

[0026] Some embodiments of an optical ferrule (200) are shown in Figures 1 to 4 The optical ferrule (200) can have an integral construction (e.g., a construction that includes a first component integrally formed on a second component). In other aspects, the optical ferrule can be a ferrule that includes pieces separately formed and adhered or otherwise fastened together. The ferrule can be made of any suitable material, including a polymer or a ceramic. The ferrule can include one or more elements that guide or help guide the ferrule in alignment with a mating ferrule when the two ferrules are mated. In some aspects, the optical ferrule and / or the mating optical ferrule can be genderless.

[0027] In some aspects, the optical ferrule (200) includes a light input surface (10), a light redirecting surface (30), and a light output surface (50). The optical ferrule (200) is configured such that light (21) entering the optical ferrule through the light input surface (10) exits the optical ferrule through the light output surface (50) after being redirected by the light redirecting surface (30). For example, as best shown in Figure 4 In some aspects, the optical ferrule (200) includes a light input surface (10), a light redirecting surface (30), and a light output surface (50). The optical ferrule (200) is configured such that light (21) entering the optical ferrule through the light input surface (10) exits the optical ferrule through the light output surface (50) after being redirected by the light redirecting surface (30). For example, as best shown in

[0028] An optical ferrule (200) can include a trench (80) for receiving and supporting an optical waveguide (20). In some aspects, the optical ferrule (200) can include a plurality of trenches (80) for receiving and securing a plurality of optical waveguides (20), the plurality of trenches being substantially parallel to one another. Each optical waveguide (20) can be received and secured in a different trench. The optical waveguides (20) according to some embodiments can be optical fibers. At the point of attachment, the fiber buffer coating and protective jacket of the optical fiber (20), if any, are stripped away to allow only the bare optical fiber to be aligned and permanently secured to the trench.

[0029] In some embodiments, the plurality of optical waveguides (20) can form a waveguide array of an optical cable. The term optical waveguide is used herein to refer to an optical element that propagates signal light. An optical waveguide can have at least one core with a cladding, where the core and cladding are configured to propagate light, for example, by total internal reflection. The optical waveguide can be, for example, a single-mode or multi-mode waveguide, a single-core fiber, a multi-core fiber, a polymer waveguide, or a planar waveguide disposed on a substrate. The waveguide can have any suitable cross-sectional shape, such as circular, square, rectangular, etc. The individual waveguides in the waveguide array can be optical fibers made of glass with a protective buffer coating. The plurality of parallel waveguides of the waveguide array can be enclosed by a jacket.

[0030] In some embodiments, when the central light ray (21) propagates in the optical ferrule from the input surface (10) to the output surface (50), the central light ray (21) propagates through different first and second portions (60, 70) of the optical ferrule. In some embodiments, the first and second portions (60, 70) have different respective first and second compositions, respectively. As shown, the first portion (60) can be disposed within a receiving space (71) defined in the optical ferrule (200). The first composition can include glass, and the second composition can include a polymer. In other embodiments, the first composition can include any material capable of handling high power density of light of suitable wavelengths. For example, the material can be a curable adhesive, or a sol-gel or nanocomposite material, which can be filled into the receiving space (71) and cured. Figure 6

[0031] In some cases, the first portion (60) can include the input surface (10). As best shown in Figure 5 , the central light ray (21) exits the first portion (60) through a first surface (61) of the first portion and enters the second portion (70) through a second surface (74) of the second portion. In some cases, the first and second surfaces (61, 74) can be in direct contact with each other, with no gap therebetween, as shown in Figure 5 In other cases, the first and second surfaces (61, 74) can define a gap (62) therebetween, as shown in​Figure 9 The gap (62) can be substantially filled with optical adhesive (63) as shown.

[0032] In some other embodiments, the optical ferrule can include a glass portion (60) including glass and at least one of the light input surface (10) and the light output surface (50), and a polymer portion (70) including polymer and disposed between the glass portion (60) and the light redirecting surface. Light propagates through the glass portion (60) and the polymer portion (70) of the optical ferrule when propagating from the light input surface (10) to the light output surface (50).

[0033] Reference is made to Figures 9 to 12 In some aspects, the glass portion (60, 60') includes only one of the light input surface (10) and the light output surface (50). In other aspects, the glass portion (60) includes only the light input surface (10). In other aspects, the glass portion (60') includes only the light output surface (50). In some other aspects, the glass portion (60", 60"') includes both the light input surface and the light output surface (10, 50). For example, in the embodiment shown in FIG. 1, the glass portion (60") includes both the light input surface (10) and the light output surface (50). Figure 11 In the embodiment shown, the glass portion (60") includes a first glass portion (60"a) and a second glass portion (60"b). The first glass portion (60"a) includes the light input surface (10), and the second glass portion (60"b) includes the light output surface. In some cases, two separate receiving spaces can be provided for the two different glass portions (60"'a, 60"b). A first receiving space can be disposed on the input surface (10) of the end facet of the optical fiber (20), and a second receiving space can be disposed on the output surface (50). In some other aspects, the glass portion (60"') can be a single continuous component, and can have a trapezoidal cross-section, as best shown in FIG. 2. Figure 12 The glass portion (60"') can be a single continuous insert extending from the input surface to the output surface of the ferrule. The glass portion having a trapezoidal cross-section can help reduce reflected light at the interface returning to the optical fiber, thus achieving better return loss.

[0034] In some aspects, when the optical fiber (20) is attached to the optical ferrule (200), light (21) from the optical fiber enters the optical ferrule through the input surface (10) and exits the optical ferrule through the output surface (50) after propagating through the first portion (60) and the second portion (70) of the optical ferrule. At least 70% of the optical power can be confined within the first portion (60) when propagating through the first portion (60). In some cases, at least 80%, or at least 90%, or at least 95% of the optical power can be confined within the first portion (60).

[0035] In some implementation schemes, such as Figures 5 to 8 As shown, the trench (80) for receiving and supporting the optical waveguide (20) may include opposite open front end (81) and open rear end (82). The optical sleeve may include a light redirection member (90) having an input surface (10) for receiving light (21) from the optical waveguide (20) received and supported in the trench (80). The light redirection member (90) also includes a means for changing the light received from the input surface (10). Figure 4 The direction (40) of the received light (22) is the light redirection side (30). The rear end (82) of the opening of the trench (80) can be disposed between the front end (81) of the opening of the trench (80) and the input surface (10), such as Figure 8 As best shown in the diagram. The opening rear end (82) of the trench and the input surface (10) define a recessed region (71) therebetween. An optically transparent glass insert (60) may be disposed in the recessed region (71), the glass insert being substantially consistent in shape with the internal shape of the recessed region (71). The glass insert (60) may be a single continuous component (60) covering all optical fibers attached to the sleeve. In some cases, the glass insert (60) may have a trapezoidal cross-section consistent with a similar internal shape to the recessed region (71). A glass insert (60) with a trapezoidal cross-section helps reduce reflected light returning to the optical fiber at the interface, thus achieving better return loss. In some cases, the glass insert (60) may include the input surface (10). According to this embodiment, the central ray (21) from the optical waveguide (20) received and supported by the trench (80) propagates through the glass insert (60) before being received and redirected by the light redirection side (30).

[0036] In some aspects of this disclosure, the recessed region (71) may define an opening top (72) and include a closed bottom (73), such as Figure 8 As shown. In other respects, the recessed area (70′) may be a through-opening that defines the top (72′) and bottom (73′) of the opening, as... Figures 13 to 15 As shown.

[0037] Figures 13 to 15 Different views of an optical sleeve assembly (300) are shown, which includes an optical sleeve (200) according to one or more embodiments described in this disclosure and at least one optical waveguide (20) received and supported in a groove (80) of the optical sleeve. In some embodiments, such as Figure 7As best shown in FIG. 1, a gap (101) can be provided between the end facet (24) of the optical waveguide (20) and the input surface (10). In some aspects, the gap (101) can be provided between the end facet (24) of the optical waveguide (20) and the glass portion (60) that includes the light input surface (10). The gap (101) between the end facet (24) and the input surface (10) or between the end facet (24) and the glass portion (60) having the input surface (10) can be less than about 2 microns long. The gap (101) can be substantially filled with an adhesive (100), as shown in FIG. 1. Figure 5 As best shown in FIG. 1, the adhesive (100) can be any substance having a refractive index similar to or the same as the material of the first portion (60) having the first component. In some cases, the glass portion (60) can include a tooth to shorten the gap (101) between the end facet (24) and the glass portion (60) to reduce the impact of the adhesive on optical performance.

[0038] Other embodiments of the present disclosure relate to a hybrid optical ferrule (200) including a light input surface (10), a light redirecting side (30), and a light output surface (50). The hybrid optical ferrule (200) includes a first ferrule portion (60) and a second ferrule portion (70). In some aspects, the first ferrule portion (60) can include glass, and the second ferrule portion (70) can include a polymer. As shown in FIG. 2, the hybrid optical ferrule (200) includes a light input surface (10), a light redirecting side (30), and a light output surface (50). Figure 16 As graphically shown, the first ferrule portion (60) has a first optical intensity damage threshold Ii, and the second ferrule portion (70) has a second optical intensity damage threshold I2. In some embodiments, the relationship between the two optical intensity damage thresholds can be such that I2 < Ii / 5. In some cases, I2 < Ii / 50. In some other cases, I2 < Ii / 500

[0039] The hybrid optical ferrule (200) is configured such that light (21) entering the optical ferrule (200) through the light input surface (10) exits the optical ferrule through the light output surface (50) after being redirected by the light redirecting side (30) and propagating through the first ferrule portion (60) and the second ferrule portion (70). The light (21) has a maximum intensity Imaxi as it propagates through the first ferrule portion (60). The light (21) has a maximum intensity Imax2 as it propagates through the second ferrule portion (70). The first and second ferrule portions (60, 70) can be arranged such that Imax2 < I2 < Imaxi < Ii.

[0040] The process for bonding the glass portion (60) in the ferrule can be combined with the optical fiber attachment process. The optical fiber can be aligned in the respective groove of the ferrule. Then, the glass portion (60) can be inserted into the recessed area (71). For example, the glass portion can be made of a suitable material such as fused silica, borosilicate, Pyrex, calcium fluoride (CaF2), quartz crystal, silicon, YAG, ZnS, etc. The recessed area (71) can be formed in an existing ferrule using laser ablation, FIB milling, mechanical machining, etching, RIE techniques, or ICP techniques. In other cases, the recessed area can be integrally formed when the ferrule is manufactured. In some cases, the recessed area (71) can need to be tapered in a direction perpendicular to the output surface (50) with a precisely controlled pinch point for controlling insertion and securing of the glass portion within the recessed area. A curable adhesive can be dispensed in the gap (101) between the end facet (24) of the optical fiber and the glass portion (60), and in the gap (62) between the glass portion (60) and the polymer portion (70). The adhesive can be cured under capillary action to obtain the hybrid optical ferrule.

[0041] In a expanded beam hybrid optical ferrule according to the present disclosure, the central light ray (21) from the optical fiber (20) diverges. According to some embodiments, the diverging light ray passes through the adhesive (100) between the end facet (24) of the optical waveguide and the glass portion (60), which experiences the highest power density. The diverging light ray (21) subsequently passes through the glass portion (60) at the second highest power density, and then continues to diverge. Since the refractive index of the glass portion is lower than the polymer portion (70) of the optical ferrule, the light diverges more than a ferrule made entirely of polymer, which enhances the handling of high power densities in the optical path from the optical fiber on the ferrule and reduces or eliminates light degradation.

Claims

1. An optical ferrule, the optical ferrule comprising: an input surface to receive and transmit a central light ray from an optical fiber attached to the optical ferrule; a light redirecting side to receive the central light ray transmitted by the input surface in a first direction and to redirect the received light in a different second direction, the redirected central light ray exiting the optical ferrule through an output surface of the optical ferrule such that when the central light ray propagates in the optical ferrule from the input surface to the output surface, the central light ray propagates through different first and second portions of the optical ferrule having different respective first and second compositions, respectively, wherein when an optical fiber is attached to the optical ferrule, light from the optical fiber enters the optical ferrule through the input surface and exits the optical ferrule through the output surface after propagating through the first and second portions of the optical ferrule such that at least 80% of the power of the light is confined within the first portion when propagating through the first portion.

2. The optical ferrule of claim 1, wherein the first composition comprises glass and the second composition comprises a polymer, wherein the optical ferrule defines a receiving space therein, wherein the first portion is disposed within the receiving space, and wherein the first portion includes the input surface.

3. The optical ferrule of claim 1, wherein the central light ray exits the first portion through a first surface of the first portion and enters the second portion through a second surface of the second portion.

4. An optical ferrule, the optical ferrule comprising a light input surface, a light redirecting surface, a light output surface, a glass portion comprising glass and at least one of the light input surface and the light output surface, and a polymer portion comprising a polymer and disposed between the glass portion and the light redirecting surface, the optical ferrule configured such that light entering the optical ferrule through the light input surface exits the optical ferrule through the light output surface after being redirected by the light redirecting surface, wherein the light propagates through the glass portion and the polymer portion of the optical ferrule when propagating from the light input surface to the light output surface, wherein the light exits the optical ferrule through the light output surface after propagating through the glass portion and the polymer portion of the optical ferrule such that at least 80% of the power of the light is confined within the glass portion when propagating through the glass portion.

5. The optical ferrule of claim 4, wherein the glass portion includes only one of the light input surface and the light output surface.

6. An optical ferrule, the optical ferrule comprising: a trench to receive and support an optical waveguide and comprising opposite open front and back ends; and a light redirecting member comprising: ​ an input surface for receiving light from an optical waveguide received and supported in the trench; a light redirecting side for changing a direction of light received from the input surface, wherein the open back end of the trench is disposed between the open front end of the trench and the input surface, the open back end of the trench and the input surface defining a recessed region therebetween; and an optically transparent glass insert disposed in the recessed region and substantially conforming in shape to an interior shape of the recessed region; wherein at least 80% of the power of the light is confined within the optically transparent glass insert when propagating through the optically transparent glass insert.

7. The optical ferrule of claim 6, wherein the recessed region defines an open top and includes a closed bottom.

8. The optical ferrule of claim 6, wherein a central light ray from the optical waveguide received and supported by the trench propagates through the glass insert before being received and redirected by the light redirecting side.

9. A hybrid optical ferrule comprising a light input surface, a light redirecting side and a light output surface, a first ferrule portion having a first optical intensity damage threshold Ii, and a second ferrule portion having a second optical intensity damage threshold I2, I2 < Ii / 5, the hybrid optical ferrule configured such that light entering the optical ferrule through the light input surface exits the optical ferrule through the light output surface after being redirected by the light redirecting side and propagating through the first ferrule portion and the second ferrule portion, wherein the light has maximum intensities Imaxi and Imax2 when propagating through the respective first and second ferrule portions, the first and second ferrule portions arranged such that Imax2 < I2 < Imaxi < Ii.

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