Patent Application
20130287342
The technology of the disclosure relates to optical fiber segments such as gradient index (GRIN) lenses and, more particularly to optical fiber segments having lead-in formations for receiving an end of an optical fiber.
Benefits of optical fiber include extremely wide bandwidth and low noise operation. Because of these advantages, optical fiber is increasingly being used for a variety of applications, including but not limited to broadband voice, video, and data transmission. Fiber optic networks employing optical fiber are being developed and used to deliver voice, video, and data transmissions to subscribers over both private and public networks. These fiber optic networks often include separated connection points linking optical fibers to provide “live fiber” from one connection point to another connection point. In this regard, fiber optic equipment is located in data distribution centers or central offices to support optical fiber interconnections.
Fiber optic connectors are provided to facilitate optical connections with optical fibers for the transfer of light. For example, optical fibers can be optically connected to another optical device, such as a light-emitting diode (LED), laser diode, or opto-electronic device for light transfer. As another example, optical fibers can be optically connected to other optical fibers through mated fiber optic connectors. In any of these cases, it is important that the end face of an optically connected optical fiber be precisely aligned with the optical device or other optical fiber to avoid or reduce coupling loss. For example, the optical fiber is disposed through a ferrule that precisely locates the optical fiber with relation to the fiber optic connector housing.
Gradient index (GRIN) lenses offer an alternative to mechanically polishing very accurate arrays of fibers. GRIN lenses focus light through a precisely controlled radial variation of the lens material's index of refraction from the optical axis to the edge of the lens. The internal structure of this index gradient can dramatically reduce the need for tightly controlled fiber array tolerances and results in a simple, compact lens. This allows a GRIN lens with flat surfaces to collimate light emitted from an optical fiber or to focus an incident beam into an optical fiber. The GRIN lens can be provided in the form of a glass rod that is disposed in a lens holder as part of a fiber optic connector. The flat surfaces of a GRIN lens allow easy bonding or fusing of one end to an optical fiber disposed inside the fiber optic connector with the other end of the GRIN lens disposed on the ferrule end face. The flat surface on the end face of a GRIN lens can reduce aberrations, because the end faces can be polished to be planar or substantially planar to the end face of the ferrule. The flat surface of the GRIN lens allows for easy cleaning of end faces of the GRIN lens.
In one embodiment, an optical fiber segment includes a glass body with a first end face at a first end of the glass body and a second end face at a second end of the glass body. At least one of the first and second end faces includes a lead-in formation having a sidewall extending inwardly from an entrance at the at least one first and second end faces to an end, the entrance sized to at least partially receive a tip of an optical fiber.
In another embodiment, a fiber assembly includes an optical fiber segment comprising a glass body, a first end face at a first end of the glass body and a second end face at a second end of the glass body. At least one of the first and second end faces includes a lead-in formation having a sidewall extending inwardly from an entrance at the at least one first and second end faces to an end. The entrance is sized to at least partially receive a tip of an optical fiber. An optical fiber has a tip at least partially located in the lead-in formation.
In another embodiment, a method of forming an optical fiber segment is provided. The method includes directing a laser beam onto an end face of the optical fiber segment. A lead-in formation is formed having a sidewall extending inwardly from an entrance at the end face using the laser beam. The entrance is sized to at least partially receive a tip of an optical fiber.
Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description that follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description present embodiments, and are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed.
Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all embodiments are shown. Indeed, the concepts may be embodied in many different forms and should not be construed as limiting herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.
Embodiments described herein generally relate to optical fiber segments such as gradient index (GRIN) lenses including lead-in formations formed in one or both end faces of the optical fiber segments. In some instances, the lead-in formations are formed in only one end face of the optical fiber segments. The lead-in formations may be formed within the optical fiber segments, themselves, and may be used in aligning a tip of an optical fiber with a centerline (or other desired alignment) of the optical fiber segments. The tips of the optical fibers may have alignment formations that can mate or otherwise cooperate with the lead-in formations of the optical fiber segments to provide the desired alignment therebetween. Such lead-in formations can provide for mechanical alignment between the optical fiber segments and their associated optical fibers. While GRIN lenses are discussed below, other optical fiber segments, such as multimode fiber segments may include the lead-in formations where the optical fiber segments behave in a fashion similar to that of GRIN lenses.
Referring to
With continuing reference to
The GRIN lenses 18 may be optically coupled or fused to optical fibers 20 disposed in a cable 22 secured to the plug 12. As will be described in greater detail below, the GRIN lenses 18 may include lead-in formations to facilitate the coupling and alignment between the GRIN lenses 18 and the optical fibers 20. In this manner, an optical connection made to the GRIN lenses 18 disposed in the GRIN lens holder 16 through a mating of the plug 12 to a receptacle or other optical component establishes an optical connection to the optical fibers 20. Alignment openings 19A, 19B are disposed in the plug 12 to assist in alignment of the plug 12 to a receptacle when the plug 12 is mated to a receptacle.
The GRIN lenses 18 disposed in the GRIN lens holder 16 of the plug 12 can offer an alternative to polishing highly accurate array tolerances onto the ends of optical fibers 20. The GRIN lenses 18 focus light through a precisely controlled radial variation of the lens material's index of refraction from the optical axis to the edge of the lens. The internal structure of this index gradient can dramatically reduce the need for tightly controlled surface curvatures and results in a simple, compact lens. This allows the GRIN lenses 18 to collimate light emitted from the optical fibers 20 or to focus an incident beam into the optical fibers 20.
In this regard,
While
Referring to
The optical fiber 20 includes the tip 62 that is sized to be received within the lead-in formation 50. In the illustrated embodiment, the tip 62 is somewhat rounded in shape having a tip periphery 64 that extends from a sidewall 66 of the optical fiber 20 to an end 68. In some embodiments, an outer diameter D1 (or width) of the optical fiber 20 is less than a maximum diameter D2 (or width) of the lead-in formation 50 at an entrance 70 of the lead-in formation 50. In some embodiments, for example, D1 may be about 95 percent or less of D2, such as about 85 percent or less of D2, such as 75 percent or less of D2, such as 65 percent or less of D2, such as 50 percent or less of D2.
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As non-limiting examples, the GRIN lenses disclosed herein may comprise a generally cylindrical glass member having a radially varying index of refraction, the glass member having a length such that the lens has a pitch of less than about 0.23. As used herein, the pitch length of the lens, Lo, is 2π/A; the fractional pitch, or, hereafter, pitch, is L/Lo=LA/2π, where L is the physical length of the lens. In various embodiments, the pitch is between about 0.08 and 0.23, such as, for example, lenses having pitches of 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09 and 0.08. Some embodiments relate to small diameter lenses, such as lenses having a diameter less than or equal to about one (1) mm, for example, 0.8 mm. In certain embodiments, lenses having a diameter less than about 1 mm are operative to produce a beam having a mode field diameter between about 350 μm and 450 μm when illuminated with a beam having a mode field diameter of about 10.4 μm.
Examples of optical devices that can interface with the GRIN lenses disclosed in the GRIN lens holders disclosed herein include, but are not limited to, fiber optic collimators, DWDMs, OADMs, isolators, circulators, hybrid optical devices, optical attenuators, MEMs devices, and optical switches.
Further, as used herein, it is intended that terms “fiber optic cables” and/or “optical fibers” include all types of single mode and multi-mode light waveguides, including one or more optical fibers that may be upcoated, colored, buffered, ribbonized and/or have other organizing or protective structure in a cable such as one or more tubes, strength members, jackets or the like. The optical fibers disclosed herein can be single mode or multi-mode optical fibers. Likewise, other types of suitable optical fibers include bend-insensitive optical fibers, or any other expedient of a medium for transmitting light signals. An example of a bend-insensitive, or bend resistant, optical fiber is ClearCurve® Multimode fiber commercially available from Corning Incorporated. Suitable fibers of this type are disclosed, for example, in U.S. Patent Application Publication Nos. 2008/0166094 and 2009/0169163, the disclosures of which are incorporated herein by reference in their entireties.
Many modifications and other embodiments of the embodiments set forth herein will come to mind to one skilled in the art to which the embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the description and claims are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. It is intended that the embodiments cover the modifications and variations of the embodiments provided they come within the scope of the appended claims and their equivalents. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
