Single-mode optical fiber with low cutoff wavelength and low bending loss

Abstract

An optical fiber has a silica-based core region having an outer radius r1 of about 4.0 [mu] m to about 4.6 [mu] m and a core volume of about 4.5% [delta]-[mu] 2 to about 5.5% [delta]-[mu] 2. The optical fiber also includes a depressed index cladding region and an outer cladding region. The recessed refractive index cladding region has an inner radius r2 such that r1 / r2 is greater than about 0.4 but less than about 0.6, and has a trench volume of between about-50% [Delta]-[mu] 2 and about-20% [Delta]-[mu] 2. The optical fiber has: a mode field diameter at 1310 nm from about 8.8 microns to about 9.4 microns; a 2 m optical cable cut-off, from about 1120 nm to about 1260 nm; a bending loss at 1310 nm, determined by a mandrel winding test performed using a mandrel having a diameter of 15 mm, of less than 1.0 dB / turn; and a zero dispersion wavelength between 1300 nm and 1324 nm.

Description

[0001] This application claims the benefit of priority under 35 USC §120 to U.S. Provisional Application No. 63 / 441,898, filed on January 30, 2023, the contents of which are relied upon and incorporated herein by reference in their entirety. Technical Field

[0002] The present disclosure relates to optical fibers having low cutoff wavelength and low bending losses, and more particularly to single-mode optical fibers for short-length applications such as co-packaged optical devices. Background Art

[0003] In current data center switches, external fiber connections terminate at a pluggable transceiver that is attached to the housing. The optical signal is then transmitted electrically from the transceiver via copper traces on the printed circuit board. However, as data rates increase, these electrical connections become unsuitable for transmitting the number of optical signals utilized. To address this issue, the industry is turning to co-packaged optics, in which the transceiver is positioned within the housing, very close to where the signals are generated within the housing. This approach effectively replaces the high-loss copper traces with low-loss optical fiber. However, to achieve such low-loss optical connections, the optical fiber used for short applications (lengths of approximately 0.5m) must be single-mode to avoid signal degradation caused by the introduction of multipath interference. It is also desirable for the optical fiber to have good bend performance and a mode field diameter that is compatible with the installed base of standard single-mode fiber and / or off-the-shelf single-mode fiber. Summary of the Invention

[0004] Co-packaged optics for data centers represent a paradigm shift that introduces several new connectivity challenges. These challenges include routing constraints and the need to achieve low-loss connectivity for hundreds of fibers within the confined space of a switch chassis. For example, in a 51.2-terabit-per-second switch chassis with four 100-gigabit-per-second optical channels per fiber, 256 optical connections must be established between the transceiver and the switch box's faceplate. Consequently, the fiber needs to meet the following requirements: (i) a cutoff wavelength low enough to ensure single-mode operation for short-length applications and low multipath interference in the O-band (1260nm to 1360nm); (ii) a mode field diameter of approximately 9 microns at 1310nm to ensure backward compatibility with standard single-mode fiber and / or the installed base of off-the-shelf single-mode fiber; and (iii) low bending losses in the O-band to enable tight routing of fibers within a confined space with a bend diameter of less than 15mm.

[0005] Embodiments of the present disclosure include optical fibers optimized for co-packaging applications.

[0006] One aspect of the present disclosure is an optical fiber comprising a silica-based core region comprising an α value of less than 20, an outer radius r1 of about 4.0 microns to about 4.6 microns, a maximum relative refractive index Δ of about 0.28% to about 0.40%, and a relative refractive index of about 0.1% to about 0.2%. 1MAX and about 4.5% Δ-μm 2 to approximately 5.5% delta-micron 2 The optical fiber also includes a depressed refractive index cladding region surrounding the core region and an outer cladding region surrounding the depressed refractive index cladding region. The depressed refractive index cladding region includes an inner radius r2 such that r1 / r2 is greater than about 0.4 but less than about 0.6, and includes an outer radius r3, a minimum relative refractive index Δ of less than about -0.2%. 3MIN and at about -50% Δ-μm 2 to about -20% Δ-μm 2 The outer cladding region includes an outer radius r4. The optical fiber has a mode field diameter at 1310 nm of about 8.8 microns to about 9.4 microns; a 2 m cable cutoff of about 1120 nm to about 1260 nm; bending losses at 1310 nm of less than 1.0 dB / turn as determined by a mandrel winding test using a mandrel having a 15 mm diameter; and a zero dispersion wavelength between 1300 nm and 1324 nm.

[0007] Additional features and advantages are set forth in the detailed description which follows, and in part will be apparent to those skilled in the art from the description or learned by practice of the embodiments as described in the written description and claims hereof, as well as the accompanying drawings. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or framework for understanding the nature and character of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings are included to provide a further understanding and are incorporated into and constitute a part of this specification. The drawings illustrate one or more embodiments and, together with the detailed description, serve to explain the principles and operations of the various embodiments. Therefore, the present disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0009] Figure 1 is a schematic diagram of a cross section of a coated optical fiber according to an embodiment of the present disclosure;

[0010] Figure 2 is a schematic diagram of a cross section of an optical fiber according to an embodiment of the present disclosure;

[0011] Figure 3 depicts the relative refractive index profile of an optical fiber according to an embodiment of the present disclosure;

[0012] Figure 4 and 5 depicts the relative refractive index profile of an optical fiber according to an exemplary embodiment of the present disclosure;

[0013] Figure 6 a graph depicting cable cutoff versus fiber length for exemplary and control optical fibers;

[0014] Figure 7-10 depicts the relative refractive index profile of an optical fiber according to an exemplary embodiment of the present disclosure;

[0015] Figure 11 is a schematic diagram illustrating multipath interference in three optical fibers with offset connections;

[0016] Figure 12 is a schematic diagram of the experimental setup used to determine multipath interference;

[0017] Figure 13 Describes the use Figure 12 A graph showing the output power of the control optical fiber measured by the device shown as a function of wavelength;

[0018] Figure 14 Describes the use Figure 12 A graph showing the output power of another control optical fiber measured by the device shown as a function of wavelength;

[0019] Figure 15 Describes the use Figure 12 A graph showing the output power of another control optical fiber measured by the device shown as a function of wavelength;

[0020] Figure 16 Describes the use Figure 12 A graph showing output power of an exemplary optical fiber according to an exemplary embodiment of the present disclosure as a function of wavelength as measured by the apparatus shown;

[0021] Figure 17 is a close-up side view of an example integrated system utilizing optical fibers disclosed herein; and

[0022] Figure 18 is comprised of a device operatively connected to a remote device Figure 17 Schematic diagram of an example optical communication system of an integrated system, where the optical system is shown as being deployed in a data center by way of example. DETAILED DESCRIPTION

[0023] The present disclosure is provided as an illustrative teaching and can be more easily understood by reference to the following description, drawings, examples and claims. To this end, those skilled in the relevant art will recognize and understand that many changes can be made to the various aspects of the embodiments described herein while still obtaining beneficial results. It will also be apparent that some of the expected benefits of the embodiments of the present invention can be obtained by selecting some features without utilizing other features. Therefore, those skilled in the art will recognize that many modifications and adaptations are possible, and in some cases can even be desired and are part of the present disclosure. Therefore, it should be understood that, unless otherwise stated, the present disclosure is not limited to the specific compositions, products, devices and methods disclosed. It should also be understood that the terms used herein are only used to describe the purpose of specific aspects and are not intended to be restrictive.

[0024] In this specification and the claims that follow, reference will be made to a number of terms which shall be defined to have the following meanings:

[0025] "Optical fiber" refers to a waveguide having a glass portion surrounded by a coating. The glass portion comprises the core and the cladding and is referred to herein as the "glass fiber."

[0026] "Radial position," "radius," or radial coordinate "r" refers to the radial position relative to the centerline of the optical fiber (r=0).

[0027] Unless otherwise specified, the "refractive index" refers to the refractive index at a wavelength of 1550 nm.

[0028] "Refractive index profile" refers to the relationship between the refractive index or relative refractive index and the radius. For the relative refractive index profiles described herein having step boundaries between adjacent core and / or cladding regions, normal variations in processing conditions may prevent the formation of clear step boundaries at the interfaces of adjacent regions. It should be understood that although the boundaries of the refractive index profiles may be described herein as step changes in refractive index, in reality the boundaries may be rounded or otherwise deviate from the ideal step function characteristics. It should also be understood that the value of the relative refractive index may vary with radial position within the core region and / or any cladding region. When the relative refractive index varies with radial position in a particular region of the optical fiber (e.g., the core region and / or any cladding region), the relative refractive index is represented by its actual or approximate functional dependence, or its value at a particular position within that region, or by an average value applicable to the entire region. Unless otherwise stated, if the relative refractive index of a region (e.g., the core region and / or any cladding region) is expressed as a single value or parameter (e.g., Δ or Δ%) applicable to the entire region, it is understood that the relative refractive index in the region is constant or approximately constant and corresponds to a single value, or it is understood that the single value or parameter represents an average value of a non-constant relative refractive index dependence on radial position in the region. For example, if "i" is a region of the glass fiber, then unless otherwise stated, the parameter Δ is i refers to the average value of the relative refractive index in the region defined by equation (1) below. Whether due to design or normal manufacturing variations, the dependence of the relative refractive index on radial position may be ramped, curved, or otherwise non-constant.

[0029] As used herein, "relative refractive index" is defined in equation (1):

[0030]

[0031] Unless otherwise stated, n i is the radial position r in the glass fiber i The refractive index at , and unless otherwise stated, n ref is the refractive index of pure silica glass. Therefore, as used herein, the relative refractive index percentage is relative to pure silica glass, which has a value of 1.444 at a wavelength of 1550 nm. As used herein, unless otherwise specified, the relative refractive index is expressed as Δ (or "delta") or Δ% (or "delta%"), and its value is given in the unit "%. The relative refractive index can also be expressed as Δ(r) or Δ(r)%.

[0032] The average relative refractive index of the fiber region (Δ ave ) is determined according to equation (2):

[0033]

[0034] where r inner is the inner radius of the region, r outer is the outer radius of the region, and Δ(r) is the relative refractive index of the region.

[0035] The refractive index of a fiber profile can be measured using commercially available instruments such as the IFA-100 Fiber Refractive Index Analyzer (Interfiber Analysis LLC, Sharon, MA USA) or the S14 Refractive Index Analyzer (Photon Kinetics, Inc., Beaverton, OR USA). These instruments measure the refractive index relative to a measurement reference refractive index, n(r) - n meas , where the reference refractive index n is measured meas Typically, a calibrated refractive index matching oil or pure silica glass is used. The measurement wavelength can be 632.5 nm, 654 nm, 677.2 nm, 654 nm, 702.3 nm, 729.6 nm, 759.2 nm, 791.3 nm, 826.3 nm, 864.1 nm, 905.2 nm, 949.6 nm, 997.7 nm, 1050 nm, or any wavelength in between. The absolute refractive index n(r) is then used to calculate the relative refractive index defined by equation (1).

[0036] The term "α profile" or "alpha profile" refers to a relative refractive index profile Δ(r) having the functional form defined in equation (3):

[0037]

[0038] where r o is the radial position where Δ(r) is the maximum value, Δ(r0)>0, r z >r0 is the radial position where Δ(r) decreases to its minimum value, and r is at r i ≤r≤r f In the range of r i is the initial radial position of the α distribution, r f is the final radial position of the α distribution, and α is a real number. Δ(r0) of the α distribution may be referred to herein as Δ max , or when referring to a specific region i of the fiber, it may be referred to as Δ imax When the relative refractive index distribution in the core region is described as an α profile, where r0 appears at the center line (r=0), r z Corresponding to the outer radius r1 of the core region, and when Δ1(r1)=0, equation (3) is simplified to equation (4):

[0039]

[0040] When the core region has a refractive index as described in equation (4), the outer radius r1 can be determined from the measured relative refractive index distribution by the following procedure. 1max , α and outer radius r 1est An estimate of is obtained by examining the measured relative refractive index profile and is used to calculate the relative refractive index at r = 0 and r = r 1est Create a trial function Δ between trial . The test function and the measured distribution (Δ meas The sum of the squares of the differences between 2 =Σ(Δ trial -Δ meas ) 2 , using the Nelder-Mead algorithm (Nelder, John A. and R. Mead, "A simplex method for function minimization," Computer Journal, 7:308-313 (1965)) at 0.1r 1est with 0.95r 1est Minimize the range of r values ​​between to determine Δ lmax , α and r1. Figure 3 The relative refractive index profile of a representative glass fiber having a core according to an embodiment of the present disclosure is shown in FIG. , depicted as an α profile.

[0041] The “core volume” V1 is defined as:

[0042]

[0043] Where r1 is the outer radius of the refractive index profile of the core region, Δ1(r) is the relative refractive index of the core region having the refractive index profile, and r is the radial position in the fiber. The core volume V1 is a positive quantity and will be expressed in units of % Δ-μm in this document. 2 It can also be expressed as %Δμm 2 or %Δ-μm 2 Or %Δ-square micrometer.

[0044] The "trench volume" is defined as:

[0045]

[0046] where r Trench,inner is the inner radius of the groove region of the refractive index profile, r Trench,outer is the outer radius of the groove region of the refractive index profile, Δ Trench(r) is the relative refractive index of the trench region of the refractive index profile, and r is the radial position in the fiber. The trench volume is an absolute and positive quantity and will be expressed herein in units of % Δ microns 2 、%Δ-μm 2 、%Δ-μm 2 or %Δμm 2 denoted by , wherein these units are used interchangeably herein. The trench region is also referred to herein as the depressed-index cladding region, and the trench volume is also referred to herein as V3.

[0047] The "mode field diameter" or "MFD" of an optical fiber is defined in equation (7) as:

[0048]

[0049] Where f(r) is the transverse component of the electric field distribution of the guided optical signal, and r is the radial position in the fiber. The "mode field diameter" or "MFD" depends on the wavelength of the optical signal and is reported herein for wavelengths of 1310 nm, 1550 nm, and 1625 nm. When referring to the mode field diameter in this article, the wavelength will be specifically indicated. Unless otherwise stated, the mode field diameter refers to the LP at the specified wavelength. 01 mold.

[0050] The “effective area” of an optical fiber is defined in equation (8) as:

[0051]

[0052] where f(r) is the transverse component of the electric field of the guided optical signal and r is the radial position in the fiber. eff ” depends on the wavelength of the optical signal and is understood herein to refer to a wavelength of 1550 nm.

[0053] As used herein, the term "attenuation" is the loss of optical power as a signal travels along an optical fiber. Attenuation is measured as specified by the IEC-60793-1-40 standard "Attenuation measurement method."

[0054] The bending resistance of an optical fiber (referred to herein as "bending loss") can be measured by induced attenuation under specified test conditions specified in the IEC-60793-1-47 standard "Measurement methods and test procedures - Macrobending losses." For example, the test conditions may require unwinding or winding the optical fiber one or more turns around a mandrel of specified diameter, for example, by winding one turn around a mandrel of 15 mm, 20 mm, or 30 mm or similar diameter (e.g., "1×15 mm diameter bending loss," "1×20 mm diameter bending loss," or "1×30 mm diameter bending loss") and measuring the increase in attenuation per turn.

[0055] As used herein, "cable cutoff wavelength" or "cable cutoff" refers to the cable cutoff test specified by the IEC 60796-1-44 standard and is defined as the wavelength at which the second-order mode experiences 19.3 dB more attenuation than the LP01 mode. Two different types of cable cutoff tests are defined in the IEC-60796-1-44 standard: (1) Method A - measures cable cutoff on uncabled optical fiber; and (2) Method B - measures cable cutoff on cabled optical fiber. According to the IEC-60796-1-44 standard, cable cutoff is measured on a fiber sample having a length of 22 m and having 80 mm diameter rings at both ends (for both Methods A and B). For the purposes of this disclosure, the cable cutoff measurements disclosed herein are made using Method A of the IEC 60796-1-44 standard. It should be noted that Method A was used to measure the cable cutoff values ​​for a 22 m sample length, as well as shorter sample lengths of 10 m, 5 m, 2 m, and 1 m, as disclosed herein.

[0056] The optical fiber disclosed herein comprises a core region, a cladding region surrounding the core region, and a coating surrounding the cladding region. The core region and the cladding region are glass. The cladding region comprises a plurality of regions. The plurality of cladding regions are preferably concentric regions. The cladding region comprises an inner cladding region, a depressed index cladding region, and an outer cladding region. As discussed further below, the depressed index cladding region can comprise various shapes, such as a square or triangular profile. The inner cladding region surrounds and is immediately adjacent to the core region. The depressed index cladding region surrounds and is immediately adjacent to the inner cladding region, such that the depressed index cladding region is radially disposed between the inner and outer cladding regions. The outer cladding region surrounds and is immediately adjacent to the depressed index cladding region.

[0057] The depressed-index cladding region has a lower relative refractive index than each of the inner and outer cladding regions. The relative refractive index of the inner cladding region can be less than, equal to, or greater than the relative refractive index of the outer cladding region. The depressed-index cladding region may each be referred to herein as a trench or trench region. In addition, the depressed-index cladding region helps reduce bending losses and microbend sensitivity.

[0058] Whenever used herein, radial position r1 and relative refractive index Δ1 or Δ1(r) refer to the core region, radial position r2 and relative refractive index Δ2 or Δ2(r) refer to the inner cladding region, radial position r3 and relative refractive index Δ3 or Δ3(r) refer to the depressed-index cladding region, and radial position r4 and relative refractive index Δ4 or Δ4(r) refer to the outer cladding region. Additionally, radial position r5( Figure 3 (not shown) refers to the primary coating, radial position r6 ( Figure 3 (not shown) refers to the secondary coating, and the radial position r7 ( Figure 3) refers to an optional triple coating.

[0059] The relative refractive index Δ1(r) has a maximum value Δ 1max and minimum value Δ 1min The relative refractive index Δ2(r) has a maximum value Δ 2max and minimum value Δ 2min The relative refractive index Δ3(r) has a maximum value Δ 3max and minimum value Δ 3min The relative refractive index Δ4(r) has a maximum value Δ 4max and minimum value Δ 4min In embodiments where the relative refractive index within a region is constant or approximately constant, the maximum and minimum values ​​of the relative refractive index are equal or approximately equal. Unless otherwise stated, if a single value is reported for the relative refractive index of a region, that single value corresponds to the average value for that region.

[0060] It will be understood that the central core region is substantially cylindrical in shape, and the surrounding inner cladding region, depressed index cladding region, outer cladding region, primary coating, and secondary coating are substantially annular in shape. The annular region is characterized by an inner radius and an outer radius. Radial positions r1, r2, r3, r4, r5, r6, and r7 are referred to herein as the outermost radii of the core region, inner cladding region, depressed index cladding region, outer cladding region, primary coating, secondary coating, and tertiary coating, respectively. In embodiments without a tertiary coating, radius r6 also corresponds to the outer radius of the optical fiber. When a tertiary coating is present, radius r7 corresponds to the outer radius of the optical fiber.

[0061] The difference between radial position r2 and radial position r1 is the thickness of the inner cladding region. The difference between radial position r3 and radial position r2 is the thickness of the depressed-index cladding region. The difference between radial position r4 and radial position r3 is the thickness of the outer cladding region. The difference between radial position r5 and radial position r4 is the thickness of the primary coating. The difference between radial position r6 and radial position r5 is the thickness of the secondary coating.

[0062] Reference will now be made in detail to illustrative embodiments of the present specification.

[0063] One embodiment relates to an optical fiber. The optical fiber comprises a glass fiber surrounded by a coating. Figure 1 An example of an optical fiber is shown in a schematic cross-sectional view in FIG. Optical fiber 10 includes a glass fiber 20 surrounded by a primary coating 50 and a secondary coating 60. Glass fiber 20 includes a core region 30 and a cladding region 40. In some embodiments, secondary coating 60 may include a pigment. Further description of glass fiber 20, primary coating 50, and secondary coating 60 is provided below. Additionally, one or more tertiary ink layers may surround secondary coating 60.

[0064] Figure 2 A schematic cross-sectional drawing of a glass fiber 20 is shown in FIG. Figure 2 As shown, cladding region 40 surrounds core region 30. Core region 30 has a higher refractive index than cladding region 40, and glass fiber 20 functions as a waveguide. In some embodiments, core region 30 and cladding region 40 have a discernible core-cladding boundary. Alternatively, core region 30 and cladding region 40 may not have a distinct boundary. In addition, cladding region 40 includes inner cladding region 42, depressed-index cladding region 43, and outer cladding region 44.

[0065] Figure 3 The idealized relative refractive index profile of the glass fiber 20 is plotted as a function of the relative refractive index Δ versus the radial coordinate r. The core region 30 has a relative refractive index Δ1 with a maximum refractive index Δ0 = Δ1 at r = 0. MAX and a gradient α profile, which will be described in more detail below. The inner cladding region 42 has a relative refractive index Δ2. The depressed-index cladding region 43 may take the form of a depressed region or trench and has a relative refractive index Δ3 with a minimum value Δ3 MIN The outer cladding region 44 has a relative refractive index Δ4, which is shown by way of example as Δ4=Δ2. In addition, as shown by way of example, Δ3 MIN <Δ2 and Δ3 MIN <Δ4. Other configurations of relative refractive index distributions are discussed further below.

[0066] Core area

[0067] The core region 30 includes silica glass, which can be undoped, up-doped, and / or down-doped. Up-doped silica glass includes silica glass doped with, for example, germanium (e.g., GeO), phosphorus (e.g., P2O5), aluminum (e.g., Al2O3), chlorine, or an alkali metal oxide (e.g., Na2O, K2O, Li2O, Cs2O, or Rb2O). In some embodiments, the core includes germanium-doped glass having a germanium concentration between about 4 wt.% and about 8 wt.%. In embodiments where the core is doped with an alkali dopant, the peak alkali concentration in the silica glass can range from about 10 ppm to about 500 ppm, or from about 30 ppm to about 400 ppm. In yet other embodiments, the silica glass of the core region 30 is free of germanium and / or chlorine; that is, the core region comprises silica glass free of germanium and / or chlorine.

[0068] Down-doped silica glass includes silica glass doped with, for example, fluorine or boron.

[0069] As discussed above, the relative refractive index of the core region 30 of the glass fiber 20 is described as an α profile having α values ​​within the following ranges: about 20 or less, or about 18 or less, or about 16 or less, or about 15 or less, or about 14 or less, or about 12 or less, or about 10 or less, or about 8 or less, or about 6 or less, or about 5 or less, or about 4 or less, or about 3 or less, or about 2 or less. Additionally or alternatively, the α values ​​are about 5 or greater, or about 6 or greater, or about 7 or greater, or about 8 or greater, or about 9 or greater, or about 10 or greater, or about 11 or greater, or about 12 or greater. In some embodiments, the α values ​​are within the range of about 2 to about 20, or about 4 to about 18, or about 6 to about 14, or about 6 to about 10, or about 5 to about 12.

[0070] The outer radius r1 of the core region 30 is in the range of about 3.0 μm to about 7.0 μm, or about 3.5 μm to about 6.5 μm, or about 4.0 μm to about 5.0 μm, or about 4.0 μm to about 4.6 μm, or about 4.2 μm to about 5.3 μm. In some embodiments, the outer radius r1 is about 4.2 μm, or about 4.3 μm, or about 4.4 μm, or about 4.5 μm, or about 5.3 μm, or about 5.4 μm, or about 5.5 μm, or about 5.6 μm.

[0071] The maximum relative refractive index Δ0 or Δ 1max In the range of about 0.50% or less, or about 0.40% or less, or about 0.39% or less, or about 0.38% or less, or about 0.37% or less, or about 0.36% or less, or about 0.35% or less, or about 0.34% or less, or about 0.33% or less, or about 0.32% or less, or about 0.30% or less, or about 0.28% or less. Additionally or alternatively, the maximum relative refractive index Δ0 or Δ 1max is about 0.10% or greater, or about 0.15% or greater, or about 0.20% or greater, or about 0.25% or greater, or about 0.28% or greater, or about 0.30% or greater. In some embodiments, the maximum relative refractive index Δ0 or Δ 1max In the following ranges: about 0.15% to about 0.50%, or about 0.20% to about 0.45%, or about 0.25% to about 0.40%, or about 0.25% to about 0.35%, or about 0.25% to about 0.40%, or about 0.25% to about 0.40%, or about 0.28% to about 0.40%, or about 0.28% to about 0.38%, or about 0.28% to about 0.36%, or about 0.28% to about 0.34%, or about 0.28% to about 0.30%.

[0072] Although Figure 3 Although not depicted, in some embodiments, the relative refractive index of the core region 30 may have a centerline dip such that the maximum refractive index of the core region 30 and the maximum refractive index of the entire optical fiber 10 are located a short distance away from the centerline of the core region 30, rather than at the centerline of the core region 30, as shown in FIG. Figure 3 Depicted.

[0073] The core volume V1 of the core region 30 may be approximately 4.0% Δ-μm 2 to about 6.0% Δ-μm 2 , or about 4.2% Δ-μm 2 to about 5.8% Δ-μm 2 , or about 4.4% Δ-μm 2 to approximately 5.6% delta-micron 2 , or about 4.5% Δ-μm 2 to approximately 5.5% delta-micron 2 , or about 4.5% Δ-μm 2 to approximately 5.0% delta-micron 2 , or about 4.5% Δ-μm 2 to about 6.0% Δ-μm 2 , or about 4.5% Δ-μm 2 to approximately 5.0% delta-micron 2 .

[0074] Inner cladding region

[0075] The inner cladding region 42 may be composed of undoped silica glass. As discussed above, the inner radius of the inner cladding region 42 is r1. The outer radius r2 of the inner cladding region 42 is in the range of about 6.0 microns to about 14.0 microns, or about 6.5 microns to about 13.5 microns, or about 7.0 microns to about 13.0 microns, or about 7.5 microns to about 12.5 microns, or about 8.0 microns to about 12.0 microns, or about 8.5 microns to about 10.5 microns, or about 8.5 microns to about 10.0 microns. In some embodiments, the outer radius r2 is about 7.5 microns, or about 8.5 microns, or about 8.9 microns, or about 9.0 microns, or about 10.2 microns.

[0076] The relative refractive index Δ2 of the inner cladding region 42 is in the range of about -0.20% to about 0.20%, or in the range of about -0.15% to about 0.15%, or in the range of about -0.10% to about 0.10%, or in the range of about -0.05% to about 0.05%. In some embodiments, the relative refractive index Δ2 is about 0.0%. The relative refractive index Δ2 is preferably constant or approximately constant.

[0077] The ratio of radius r1 to radius r2 (r1 / r2) may be in the range of about 0.3 to about 0.6, or about 0.4 to about 0.5, or about 0.3 to about 0.5, or about 0.4 to about 0.6. The ratio of radius r1 to radius r2 should preferably be less than about 0.6 in order to achieve low bending losses and ensure that the zero dispersion wavelength is between 1300 nm and 1324 nm.

[0078] It should also be noted that in some embodiments, the optical fibers disclosed herein do not include an inner cladding region 42. Instead, in these embodiments, a depressed-index cladding region 43 is located immediately adjacent to the core region 30.

[0079] depressed-index cladding region

[0080] The depressed index cladding region 43 comprises down-doped silica glass. In some embodiments, the depressed index cladding region 43 is down-doped with fluorine or boron. However, down-doping of the depressed index cladding region 43 can also be achieved by introducing voids into the silica glass.

[0081] As discussed above, the inner radius of the depressed-index cladding region 43 is r2. The outer radius r3 of the depressed-index cladding region 43 is in the range of about 8 microns to about 20 microns, or about 10 microns to about 18 microns, or about 12 microns to about 16 microns, or about 12 microns to about 15 microns, or about 10 microns to about 15 microns. In some embodiments, the outer radius r3 is about 12.5 microns, or about 13.9 microns, or about 14.9 microns, or about 15.2 microns, or about 16.3 microns.

[0082] In some embodiments, the depressed index cladding region 43 is a depressed index cladding region forming a groove design. The groove design may be an offset groove. The minimum relative refractive index Δ3 (Δ 3MIN ) is about -0.20% or less, or about -0.22% or less, or about -0.25% or less, or about -0.28% or less, or about -0.30% or less, or about -0.32% or less, or about -0.35% or less, or about -0.38% or less, or about -0.40% or less, or in the range of about -0.20% to about -0.60%, or about -0.25% to about -0.55%, or about -0.30% to about -0.50%, or about -0.35% to about -0.45%, or about -0.35% to about -0.48%. In some embodiments, the minimum relative refractive index Δ3 of the depressed-index cladding region 43 is about -0.39%, or about -0.43%, or about -0.46%, or about -0.47%.

[0083] The transition region from the inner cladding region 42 to the depressed index cladding region 43 is Figure 3 In addition, the transition region from the depressed index cladding region 43 to the outer cladding region 44 is shown as a step change. Figure 3 . However, it should be understood that the step changes are each idealized and that the transition region may not actually be strictly vertical. Instead, the transition region may each have a slope or curvature.

[0084] The depressed index cladding region 43 may have a square profile, such as Figure 3 However, it is contemplated that the depressed-index cladding region 43 may have other profile configurations.

[0085] Using equation (6) above, the "volume" V3 of the depressed-index cladding region 43 is defined in equation (9) as:

[0086]

[0087] where Δ 3-5 =(Δ3(r)-Δ5).

[0088] The trench volume V3 of the depressed index cladding region 43 may be approximately -20% Δ-μm 2 to about -60% Δ-μm 2 , or about -20% Δ-μm 2 to about -50% Δ-μm 2 , or about -25% Δ-μm 2 to about -55% Δ-μm 2 , or about -30% Δ-μm 2 to about -50% Δ-μm 2 , or about -32% Δ-μm 2 to about -48% Δ-μm 2 In some embodiments, the trench volume V3 is approximately -34% Δ-μm 2 , or about -38% Δ-μm 2 , or about -44% Δ-μm 2 , or about -46% Δ-μm 2 .

[0089] Without wishing to be bound by theory, the offset trench design with the trench volumes disclosed herein provides the low bending loss values ​​disclosed herein. It should be noted that such low bending losses can be achieved at the relatively large mode field diameter values ​​disclosed herein. Additionally, the position of the depressed index cladding region 43 is optimized to maintain the low cable cutoff values ​​disclosed herein and ensure that the zero dispersion wavelength is between 1300 nm and 1324 nm.

[0090] Outer cladding area

[0091] The outer cladding region 44 can be composed of undoped silica glass. As discussed above, the inner radius of the outer cladding region 44 is r3. The outer radius r4 of the outer cladding region 44 is in the range of about 40.0 microns to about 65 microns, or about 45.0 microns to about 62.5 microns, or about 50.0 microns to about 60.0 microns, or about 52.5 microns to about 57.5 microns. In some embodiments, the outer radius r4 of the outer cladding region 44 is about 62.5 microns.

[0092] The relative refractive index Δ4 of the outer cladding region 44 is in the range of about -0.20% to about 0.20%, or in the range of about -0.15% to about 0.15%, or in the range of about -0.10% to about 0.10%, or in the range of about -0.05% to about 0.05%. In some embodiments, the relative refractive index Δ4 is ​​about 0.0%. The relative refractive index Δ4 is ​​preferably constant or approximately constant. Furthermore, in some embodiments, the relative refractive index Δ4 is ​​equal to or substantially equal to the relative refractive index Δ2.

[0093] outer coating

[0094] The primary coating 50 closely surrounds the glass fiber 20, and the secondary coating 60 closely surrounds the primary coating 50. In some embodiments, the primary coating 50 comprises a low modulus material, and the secondary coating 60 comprises a high modulus material. One or more of the materials may be, for example, acrylate.

[0095] Optical fiber 10 may also include a tertiary coating surrounding secondary coating 60. The tertiary coating may include a pigment, ink, or other colorant to mark the optical fiber for identification purposes and typically has a Young's modulus similar to that of the secondary coating.

[0096] When no tertiary layer is applied, the outer diameter of the secondary coating 60 is the outer diameter of the optical fiber 10. The outer diameter of the secondary coating 60 can be about 250 microns or less, or about 220 microns or less, or about 210 microns or less, or about 200 microns or less, or about 190 microns or less, or about 180 microns or less, or about 170 microns or less.

[0097] nature

[0098] The optical fibers disclosed herein have the advantageous properties of balancing low cable cutoff with a large mode field diameter and low bending losses. The low cable cutoff allows the optical fibers disclosed herein in lengths of 2 m or less to be single-mode at 1260 nm with low multipath interference. The large mode field diameter allows the optical fibers disclosed herein to have low coupling losses when coupled to a transceiver and allows the optical fibers to be highly compatible with standard single-mode optical fibers having mode field diameters at 1310 nm in the range of 8.6 microns to 9.5 microns. Furthermore, the low bending losses allow the optical fibers disclosed herein to be routed around sharp bends as small as 10 mm in diameter without incurring more than 2 dB of induced losses.

[0099] With respect to bending losses, the optical fibers disclosed herein meet the G.657.A1 standard, exhibiting bending losses of less than 0.75 dB / turn at a wavelength of 1550 nm when wound on a 20 mm diameter mandrel. Some embodiments of the optical fibers disclosed herein also meet the G.657.A2 standard, exhibiting bending losses of less than 0.5 dB / turn at a wavelength of 1550 nm when wound on a 15 mm diameter mandrel. It should be noted that these bending loss standards are achieved while maintaining a large mode field diameter compared to conventional optical fibers.

[0100] The optical fibers disclosed herein have bending losses at 1310 nm of less than about 1.00 dB / turn, or less than about 0.75 dB / turn, or less than about 0.50 dB / turn, or less than about 0.40 dB / turn, or less than about 0.25 dB / turn, or less than about 0.20 dB / turn, or less than about 0.15 dB / turn, or less than about 0.14 dB / turn, or less than about 0.13 dB / turn, or less than about 0.12 dB / turn, or less than about 0.11 dB / turn, or less than about 0.10 dB / turn, or less than about 0.09 dB / turn, or less than about 0.08 dB / turn, or less than about 0.07 dB / turn, or less than about 0.06 dB / turn, or less than about 0.05 dB / turn, as determined by winding testing around a mandrel having a 15 mm diameter.

[0101] Additionally, the optical fibers disclosed herein have bending losses at 1310 nm of less than about 2.00 dB / turn, or less than about 1.50 dB / turn, or less than about 1.00 dB / turn, or less than about 0.50 dB / turn, or less than about 0.40 dB / turn, or less than about 0.30 dB / turn, or less than about 0.28 dB / turn, or less than about 0.26 dB / turn, or less than about 0.24 dB / turn, or less than about 0.22 dB / turn, or less than about 0.20 dB / turn, or less than about 0.18 dB / turn, or less than about 0.16 dB / turn, or less than about 0.14 dB / turn, or less than about 0.12 dB / turn, or less than about 0.10 dB / turn, as determined by a winding test on a mandrel having a 10 mm diameter.

[0102] Additionally, the optical fibers disclosed herein have bending losses at 1550 nm of less than about 2.00 dB / turn, or less than about 1.75 dB / turn, or less than about 1.50 dB / turn, or less than about 1.25 dB / turn, or less than about 1.00 dB / turn, or less than about 0.75 dB / turn, as determined by winding testing around a mandrel having a 15 mm diameter.

[0103] Additionally, the optical fibers disclosed herein have bending losses at 1550 nm of less than about 4.00 dB / turn, or less than about 3.50 dB / turn, or less than about 3.00 dB / turn, or less than about 2.50 dB / turn, or less than about 2.00 dB / turn, or less than about 1.50 dB / turn, as determined by winding testing around a mandrel having a 10 mm diameter.

[0104] In addition to the low bending losses disclosed above, the optical fibers disclosed herein have a mode field diameter at a wavelength of 1310 nm of about 8.4 μm or greater, or about 8.6 μm or greater, or about 8.8 μm or greater, or about 8.9 μm or greater, or about 9.0 μm or greater, or about 9.1 μm or greater, or about 9.2 μm or greater, or about 9.3 μm or greater, or about 9.4 μm or greater, or about 9.5 μm or greater, or about 9.6 μm or greater. In some embodiments, the mode field diameter is in a range of about 8.4 μm to about 9.7 μm, or about 8.6 μm to about 9.5 μm, or about 8.8 μm to about 9.4 μm, or about 9.0 μm to about 9.4 μm. For example, the mode field diameter at a wavelength of 1310 nm is about 8.88 μm, or about 8.90 μm, or about 8.91 μm, or about 9.22 μm, or about 9.34 μm.

[0105] The optical fibers disclosed herein have a mode field diameter at a wavelength of 1550 nm of about 9.2 μm to about 11.0 μm, or about 9.4 μm to about 10.8 μm, or about 9.8 μm to about 10.6 μm, or about 10.0 μm to about 10.4 μm, or about 9.8 μm to about 10.4 μm. In some embodiments, the mode field diameter at a wavelength of 1550 nm is about 9.90 μm, or about 10.09 μm, or about 10.10 μm, or about 10.24 μm, or about 10.31 μm.

[0106] The optical fibers disclosed herein have a 22 m cable cutoff of about 1200 nm or less, or about 1195 nm or less, or about 1190 nm or less, or about 1185 nm or less, or about 1180 nm or less, or about 1175 nm or less, or about 1170 nm or less, or about 1160 nm or less, or about 1150 nm or less, or about 1140 nm or less, or about 1140 nm or less, or about 1120 nm or less, or about 1110 nm or less, or about 1100 nm or less. For example, the 22 m cable cutoff is from about 1060 nm to about 1200 nm, or from about 1060 nm to about 1180 nm, or from about 1080 nm to about 1180 nm, or from about 1100 nm to about 1180 nm, or from about 1100 nm to about 1160 nm, or from about 1120 nm to about 1180 nm. In an embodiment, the 22m cable cutoff is about 1129 nm, or about 1133 nm, or about 1155 nm, or about 1178 nm.

[0107] The optical fibers disclosed herein have a 2 m cable cutoff of about 1260 nm or less, or about 1250 nm or less, or about 1240 nm or less, or about 1230 nm or less, or about 1220 nm or less, or about 1210 nm or less, or about 1200 nm or less, or about 1190 nm or less, or about 1180 nm or less, or about 1170 nm or less, or about 1160 nm or less, or about 1150 nm or less, or about 1140 nm or less, or about 1130 nm or less, or about 1120 nm or less. For example, the cutoff for a 2m cable is about 1120 nm to about 1260 nm, or about 1120 nm to about 1250 nm, or about 1120 nm to about 1240 nm, or about 1140 nm to about 1220 nm, or about 1160 nm to about 1200 nm, or about 1180 nm to about 1260 nm, or about 1190 nm to about 1260 nm, or about 1200 nm to about 1250 nm, or about 1200 nm to about 1240 nm, or about 1210 nm to about 1250 nm. In an embodiment, the cutoff for a 2m cable is about 1195 nm, or about 1198 nm, or about 1205 nm, or about 1222 nm.

[0108] The optical fibers disclosed herein have a 1 m cable cutoff of about 1260 nm or less, or about 1250 nm or less, or about 1240 nm or less, or about 1230 nm or less, or about 1220 nm or less, or about 1210 nm or less, or about 1200 nm or less, or about 1190 nm or less, or about 1180 nm or less, or about 1170 nm or less, or about 1160 nm or less, or about 1150 nm or less, or about 1140 nm or less. For example, the 1 m cable cutoff is about 1140 nm to about 1260 nm, or about 1140 nm to about 1250 nm, or about 1140 nm to about 1240 nm, or about 1140 nm to about 1220 nm, or about 1140 nm to about 1200 nm, or about 1190 nm to about 1270 nm, or about 1200 nm to about 1260 nm, or about 1200 nm to about 1250 nm, or about 1200 nm to about 1240 nm, or about 1210 nm to about 1250 nm. In an embodiment, the 1 m cable cutoff is about 1195 nm, or about 1198 nm, or about 1205 nm, or about 1222 nm.

[0109] The MAC value of an optical fiber is used to determine the bend sensitivity of the optical fiber. It is the ratio of the mode field diameter (converted to nm) to the 22m cable cutoff (nm). A smaller MAC value advantageously results in lower bending losses. It should be noted that if the mode field diameter decreases and / or if the cable cutoff increases, the MAC value will decrease. In embodiments disclosed herein, the optical fiber has a MAC value at 1550 nm of about 6.0 to about 8.0, or about 6.2 to about 7.8, or about 6.4 to about 7.6, or about 6.6 to about 7.6, or about 6.8 to about 7.6, or about 7.0 to about 7.6, or about 7.2 to about 7.6, or about 6.8 to about 8.0. In embodiments, the MAC value at 1550 nm is about 6.92, or about 7.01, or about 7.43, or about 7.42, or about 7.53.

[0110] Furthermore, the optical fiber disclosed herein has an effective area of ​​approximately 60.0 microns at a wavelength of 1310 nm. 2 or larger, or about 62.0 microns 2 or larger, or about 64.0 microns 2 or larger, or about 66.0 microns 2 or larger, or about 70.0 microns 2 or smaller, or approximately 69.0 microns 2 or smaller, or about 68.0 microns 2 or smaller, or about 67.0 microns 2 or smaller, or about 66.0 microns 2 or smaller, or about 65.0 microns 2or smaller, or approximately 64.0 microns 2 In some embodiments, the effective area at a wavelength of 1310 nm is about 60 microns. 2 to about 70 microns 2 , or about 62 microns 2 to about 68 microns 2 , or about 64 microns 2 to about 66 microns 2 The effective area of ​​the optical fiber at a wavelength of 1550nm is also about 75 microns. 2 or larger, or about 78 microns 2 or larger, or about 80 microns 2 or larger, or about 82 microns 2 or larger, or about 85 microns 2 or larger, or about 87 microns 2 Alternatively or additionally, the effective area at a wavelength of 1550 nm is about 95 microns 2 or smaller, or about 90 microns 2 or smaller, or about 85 microns 2 In some embodiments, the effective area at a wavelength of 1550 nm is about 75 microns. 2 to about 90 microns 2 within the range.

[0111] The optical fiber disclosed herein also has a zero dispersion wavelength (λ0) of about 1290 nm to about 1330 nm. For example, the zero dispersion wavelength can be about 1295 nm to about 1325 nm, about 1300 nm to about 1324 nm, or about 1305 nm to about 1315 nm. For example, the zero dispersion wavelength can be about 1280 nm, about 1285 nm, about 1289 nm, about 1290 nm, about 1300 nm, about 1301 nm, about 1305 nm, about 1306 nm, about 1310 nm, about 1315 nm, or about 1320 nm.

[0112] Additionally, the optical fibers disclosed herein have an attenuation of less than or equal to about 0.35 dB / km at a wavelength of 1310 nm, less than or equal to about 0.2 dB / km at a wavelength of 1550 nm, and less than or equal to about 0.2 dB / km at a wavelength of 1625 nm. In some embodiments, the attenuation is less than or equal to about 0.19 dB / km, or less than or equal to about 0.18 dB / km, or less than or equal to about 0.185 dB / km at a wavelength of 1550 nm. In some embodiments, the attenuation is less than or equal to about 0.34 dB / km, or less than or equal to about 0.33 dB / km, or less than or equal to about 0.32 dB / km at a wavelength of 1310 nm.

[0113] According to aspects of the present disclosure, the optical fiber has a dispersion at 1310 nm in the range of about -1.5 ps / nm / km to about 1.5 ps / nm / km, and a dispersion slope at 1310 nm of about 0.05 ps / nm. 2 / km to 0.1ps / nm 2 / km. For example, the dispersion at 1310 nm is about -1.2 ps / nm / km to about 1.2 ps / nm / km, or about -1.0 ps / nm / km to about 1.0 ps / nm / km. For example, the dispersion at 1310 nm is about -1.1 ps / nm / km, or about -0.8 ps / nm / km, or about -0.7 ps / nm / km, or about -0.4 ps / nm / km, or about -0.3 ps / nm / km, or about 0.1 ps / nm / km, or about 0.2 ps / nm / km. In some examples, the dispersion slope at 1310 nm is about 0.05 ps / nm 2 / km to about 0.095ps / nm 2 / km, or about 0.06ps / nm 2 / km to about 0.1ps / nm 2 / km, about 0.07ps / nm 2 / km to about 0.1ps / nm 2 / km, about 0.08ps / nm 2 / km to about 0.1ps / nm 2 / km.

[0114] Embodiments of the disclosed optical fiber allow single-mode operation at wavelengths less than 1260 nm, less than 1200 nm, or even less than 1140 nm with an deployed length of 5 m or less. Embodiments of the disclosed optical fiber allow single-mode operation at wavelengths less than 1260 nm, less than 1200 nm, or even less than 1140 nm with an deployed length of 2 m or less. Embodiments of the disclosed optical fiber allow single-mode operation at wavelengths less than 1260 nm, less than 1200 nm, or even less than 1140 nm with an deployed length of 1 m or less. Embodiments of the disclosed optical fiber allow single-mode operation at wavelengths less than 1260 nm, less than 1200 nm, or even less than 1140 nm with an deployed length of 0.5 m or less.

[0115] Exemplary embodiments

[0116]

[0014] Provided below are exemplary embodiments of the optical fibers disclosed herein.The following examples are intended to be illustrative and are not intended to limit the scope of the present disclosure.

[0117] Table 1 below provides two exemplary embodiments, each having a square depressed-index cladding region according to aspects of the present disclosure. As shown below in Table 1, the optical fibers of Exemplary Examples 1 and 2 both have low cable cutoff and low bending losses, along with relatively large mode field diameters.

[0118] Table 1

[0119]

[0120]

[0121] Figure 4 The relative refractive index distribution of Exemplary Example 1 is shown, and Figure 5 The refractive index profile of Exemplary Example 2 is shown. In addition, the cable cutoff of Exemplary Examples 1 and 2 is plotted as a function of fiber length, as shown in FIG. Figure 6 In addition, Figure 6 The cable cutoff values ​​for three control fibers (Control Examples 1, 2, and 3) are shown in FIG. Control Example 1 comprises an optical fiber having a step-index core surrounded by an offset trench having a delta-micron ratio of about -71%. 2 This large trench volume inhibits the ability of higher order modes to escape into the cladding region, and therefore, for deployed lengths of 2 m or less, the fiber is not single-mode at 1260 nm. Comparative Example 2 includes an optical fiber having a graded-index core surrounded by a depressed-index trench having a volume of only -3.4% Δ-μm. 2 The trench volume is too small to achieve low bending losses at bend diameters of 15 mm or less. Comparative Example 3 includes an optical fiber having a graded-index core having approximately 5.9% delta-micron 2 The relatively high volume of the optical fiber is too large to make it single-mode at 1260 nm for deployed lengths of 2 m or less.

[0122] like Figure 6As shown, Exemplary Examples 1 and 2 provide cable cutoffs below 1260 nm for relatively short lengths (approximately 2 m) and below 1200 nm for relatively long lengths (approximately 22 m). Therefore, Exemplary Examples 1 and 2 have advantages for use in co-packaged optical applications. In contrast, due to the larger trench volume, Comparative Example 1 has a 22 m cable cutoff above 1260 nm for lengths of at least 10 m or less. Furthermore, the cable cutoff of Comparative Example 1 is much more length-dependent than either of Exemplary Fibers 1 and 2 (notably, the cable cutoff of Comparative Example 1 increases very rapidly for lengths less than 5 m). Comparative Example 2 has a 22 m cable cutoff wavelength of less than 1260 nm, but for lengths of 2 m or less, the cable cutoff wavelength is greater than 1260 nm. Furthermore, the macrobending losses at a 15 mm bend diameter are 11.4 dB / turn at 1550 nm and 0.3 dB / turn at 1310 nm, which are too high to allow the fiber to be routed within the confined footprint of a co-packaged optical device without incurring excessive losses. Comparative Example 3 has a 22 m cable cutoff wavelength of less than 1260 nm for relatively long lengths, but a 1 m cable cutoff wavelength greater than 1260 nm. This can result in high levels of MPI in the 1260-1360 nm wavelength range when this fiber is used in applications with lengths of 1 m or less.

[0123] Table 2 below provides four exemplary embodiments, each having a square depressed-index cladding region according to aspects of the present disclosure. As shown below in Table 2, the optical fibers of Exemplary Examples 3-6 all have low cable cutoff and low bending losses, along with relatively large mode field diameters.

[0124] Table 2

[0125]

[0126]

[0127] Figure 7 Relative refractive index distributions of Exemplary Example 5 and Exemplary Example 6 are shown below.

[0128] Table 3 below provides four exemplary embodiments, each having a square depressed-index cladding region according to aspects of the present disclosure. As shown below in Table 3, the optical fibers of Exemplary Examples 7-11 all have low cable cutoff and low bending losses, along with relatively large mode field diameters.

[0129] Table 3

[0130]

[0131]

[0132] Figure 8 The refractive index distributions of Exemplary Examples 7 and 8 are shown.

[0133] Table 4 below provides two exemplary embodiments, each having a square depressed-index cladding region according to aspects of the present disclosure. As shown below in Table 4, the optical fibers of Exemplary Examples 12 and 13 both have low cable cutoff and low bending losses, along with relatively large mode field diameters.

[0134] Table 4

[0135]

[0136]

[0137] Table 5 below provides three exemplary embodiments, each having a triangular depressed-index cladding region according to aspects of the present disclosure. As shown below in Table 5, the optical fibers of Exemplary Examples 14-16 all have low cable cutoff and low bending losses, along with relatively large mode field diameters.

[0138] Table 5

[0139]

[0140]

[0141] Table 6 below provides five exemplary embodiments, each having a triangular depressed-index cladding region according to aspects of the present disclosure. As shown below in Table 6, the optical fibers of Exemplary Examples 17-21 all have low cable cutoff and low bending losses, along with relatively large mode field diameters.

[0142] Table 6

[0143]

[0144]

[0145] Figure 9 The refractive index distribution of Exemplary Example 17 is shown, and Figure 10 The refractive index distribution of Exemplary Example 18 is shown.

[0146] Multipath interference

[0147] Multipath interference (MPI) is a propagation phenomenon caused when an optical signal reaches its destination via two or more optical paths. It provides a metric for quantifying single-mode behavior in optical fibers. The MPI phenomenon can be observed when a short length of single-mode optical fiber supporting the LP01 mode and the higher-order LP11 mode is connected or spliced ​​between two system components (e.g., another optical fiber with an offset in a transceiver, switch, or connection). This phenomenon is described in Olivero, M., Greborio, L., Orta, R., Pellegrino, P., Perrone, G., and Regio, P., “Multipath Interference Characterization of Bend-Insensitive Optical Fibers and Short Jumpers,” Appl. Opt., Vol. 55, No. 11, pp. 2998-3005 (April 10, 2016), which is incorporated herein by reference.

[0148] Figure 11 An illustrative example of the MPI phenomenon is shown, where fiber B is connected to both fiber A and fiber C, with an offset between these connections. Figure 11 In the example, most of the light in the LP01 mode from fiber A (input fiber) is coupled into the LP01 mode of fiber C (output fiber) through a shorter length of fiber B (fiber under test). However, at the connection between fibers A and B, some of the light from the LP01 mode of fiber A is coupled into the LP11 mode of fiber B, and if the attenuation of the LP11 mode in fiber B is low, then a portion of the light in the LP11 mode in fiber B will be coupled back into the LP01 mode of fiber C. This light can interfere with the portion of the signal that propagates only in the LP01 mode and is directly coupled from fiber A to fiber C. When MPI is present, the output power will exhibit rapid sinusoidal oscillations with wavelength. Using equation (10), calculate the power of the system (e.g. Figure 11 MPI penalty in systems with

[0149] MPI(dB)=20log[0.5(10 Δ PtP (dB) / 10 -1) / (10 Δ PtP (dB) / 10 +1)] (10)

[0150] where Δ PtP is the magnitude of the peak-to-peak oscillation of the transmission loss in dB. Table 7 shows the values ​​for different Δ PtP Value calculated as MPI penalty.

[0151] Table 7

[0152] <![CDATA[Δ PtP ]]> MPI 0.05 -50.8 0.1 -44.8 0.15 -41.3 0.2 -38.8 0.25 -36.8 0.3 -35.3 0.35 -33.9 0.4 -32.8 0.45 -31.7 0.5 -30.8

[0153] The MPI penalty of the optical fiber disclosed herein is based on the use of Figure 12 The magnitude of the peak-to-peak oscillation of the output power measured by the experimental setup shown is calculated. Figure 12 As shown, the wavelength range of 1270-1330nm from a superluminescent diode (SLD) source is transmitted through an isolator, polarizer, and polarization scrambler and then coupled into a 25m length of single-mode optical fiber. This single-mode optical fiber has a 22m cable cutoff less than 1260nm, thereby enabling the single-mode optical fiber to be used as a mode filter to ensure that only the LP01 mode is coupled into the fiber under test (FUT). The offset connector at the input and output of the FUT is calibrated to produce a loss of 0.5dB, and the output signal is transmitted through a single-mode patch cord into an optical signal analyzer (OSA). MPI penalty measurement is performed on a 1m length of optical fiber deployed in a straight configuration.

[0154] use Figure 12 The experimental setup shown measures the relationship between output power and wavelength for Control Example 1 and Figure 13 The magnitude of the peak-to-peak oscillation of the output power is Δ PtP = 0.3 dB, corresponding to an MPI value of approximately -35 dB calculated (using equation (10)).

[0155] use Figure 12 The experimental setup shown measures the relationship between output power and wavelength for Control Example 2 and Figure 14 The magnitude of the peak-to-peak oscillation of the output power is Δ PtP = 0.35 dB, corresponding to an MPI value of approximately -34 dB calculated (using equation (10)).

[0156] use Figure 12 The experimental setup shown measures the relationship between output power and wavelength for comparative example 3 and Figure 15 At wavelengths between 1270 nm and 1290 nm, the magnitude of the peak-to-peak oscillation of the output power is plotted in [1]. PtP Between 0.2dB and 0.25dB, corresponding to MPI values ​​in the range of -36dB to -39dB calculated (using equation (10)). However, at longer wavelengths, the magnitude of the peak-to-peak oscillations in the output power Δ PtP Less than 0.1 dB, corresponding to an MPI value of less than about -45 dB.

[0157] use Figure 12The experimental setup shown measures the output power versus wavelength for Exemplary Example 2 and Figure 16 The magnitude of the peak-to-peak oscillation of the output power Δ PtP is less than 0.1 dB, corresponding to an MPI value of less than about -45 dB (using equation (10)).

[0158] In embodiments disclosed herein, the optical fiber has a maximum MPI penalty of about -30 dB or less, or about -35 dB or less, or about -40 dB or less, or about -45 dB or less, or about -50 dB or less, or about -55 dB or less, or about -60 dB or less in the wavelength range of 1270 nm to 1330 nm. In embodiments, the optical fiber has a maximum MPI penalty of about -30 dB to about -60 dB, or about -35 dB to about -55 dB, or about -40 dB to about -50 dB, or about -40 dB to about -60 dB, or about -45 dB to about -60 dB in the wavelength range of 1270 nm to 1330 nm. In embodiments, the maximum MPI penalty values ​​disclosed above are for optical fibers exceeding one meter in length.

[0159] Integrated systems and optical communication systems

[0160] In addition to the low bend loss, low cable cutoff, and large mode field diameter optical fibers disclosed herein, the present disclosure also extends to integrated systems incorporating optical fibers and optical communication systems employing the integrated systems.

[0161] Figure 17 FIG2 is a side view of an example integrated system 100 including an example VCSEL-based transceiver 110 and an optical fiber 10 disclosed herein. The example transceiver 110 includes a photonic integrated circuit (PIC) 120 having an active device 122. The active device 122 may include a light source (e.g., an LED, a vertical-cavity surface-emitting laser (VCSEL), a distributed feedback (DFB) laser, or a semiconductor laser) and an optical receiver (e.g., a photodetector). The PIC 120 is electrically connected to a printed circuit board (PCB) 130 via electrical connectors 140, shown as a ball grid array, for example. A waveguide structure 150 including at least one waveguide 156 is operably positioned adjacent to the PIC 120 such that light 126 emitted by the light-emitting active device 122 is coupled into the waveguide. The waveguide 156 is shown, by way of example, as being evanescently coupled to the optical fiber 10 such that light 126 can be coupled between the waveguide and the optical fiber. The waveguide structure 150 and the PIC 120 constitute a photonic device 160.

[0162] Active device 122 is coupled to optical fiber 10. In one embodiment, active device 122 operates at 1060 nm or a surrounding wavelength (e.g., 990 nm, 1015 nm, 1040 nm, and / or 1064 nm). In an example, active device 122 is a single-mode VCSEL. In another embodiment, active device 122 operates at a wavelength of 1310 nm or a surrounding wavelength (e.g., 1260 nm-1360 nm). In an example, active device 122 is a single-mode laser.

[0163] As is known in the art, the integrated system 100 may also include peripheral devices such as modulators, detectors, multiplexers, demultiplexers, etc.

[0164] The low cutoff provided by optical fiber 10 reduces coupling losses between the optical fiber and waveguide 156 of photonic device 160 when operating at wavelengths less than 1080 nm. Conventional single-mode optical fibers have a cable cutoff wavelength greater than 1200 nm and are therefore multimode at wavelengths less than 1200 nm. Using these fibers with lasers operating in the 980-1080 nm window can result in degradation of signal integrity due to multipath interference (MPI). While LP11 and other higher-order modes can be removed by winding the fiber around a small-diameter mandrel, this can result in losses of several dB and is ineffective for bend-insensitive fibers. Therefore, it is desirable to have an optical fiber with a cable cutoff less than 1260 nm and a sufficiently high MFD to ensure low coupling losses so that the fiber can also be used with transceivers operating at wavelengths close to 1310 nm. Advantageously, embodiments of the optical fiber 10 described herein have a cable cutoff of less than 1260 nm and a sufficiently high MFD (9.4 microns ≥ MFD ≥ 8.8 microns) such that the optical fiber 10 can be advantageously used with transceivers (transmitters and / or receivers) operating at wavelengths near 1310 nm.

[0165] Figure 18 1 is a schematic diagram of an example optical communication system 200 including the integrated system 100, with the optical fiber 10 optically connected to a remote device 210. In the example, the optical communication system 200 is deployed within a data center 250, and the remote device 210 is a data center device, such as a server (e.g., a rack-mounted server) or another data center component, such as a router, a switch, etc.

[0166] It will be apparent to those skilled in the art that various modifications may be made to the preferred embodiments of the present disclosure described herein without departing from the spirit or scope of the present disclosure as defined in the appended claims. Therefore, the present disclosure covers modifications and variations that fall within the scope of the appended claims and their equivalents.

Claims

1. An optical fiber, comprising: A silica-based core region comprising an α value of less than 20, an outer radius r1 of about 4.0 microns to about 4.6 microns, a maximum relative refractive index Δ of about 0.28% to about 0.40%, 1MAX and about 4.5% Δ-μm 2 to approximately 5.5% delta-micron 2 The core volume of the fiber; A depressed-index cladding region surrounding the core region, the depressed-index cladding region including an inner radius r2 such that r1 / r2 is greater than about 0.4 but less than about 0.6, and including an outer radius r3, a minimum relative refractive index Δ less than about -0.2% 3MIN and at about -50% Δ-μm 2 to about -20% Δ-μm 2 The volume of the trench between an outer cladding region surrounding the depressed-index cladding region, the outer cladding region comprising an outer radius r4, The optical fiber comprises: The mode field diameter at 1310 nm is about 8.8 microns to about 9.4 microns, The cutoff of 2m optical cable is about 1120nm to about 1260nm. Bending losses at 1310 nm, determined by a mandrel winding test using a mandrel comprising a 15 mm diameter, are less than 1.0 dB / turn, and The zero dispersion wavelength is between 1300nm and 1324nm.

2. The optical fiber of claim 1, wherein the 2 m cable cutoff is from about 1120 nm to about 1240 nm.

3. The optical fiber of claim 2, wherein the 2 m cable cutoff is from about 1140 nm to about 1220 nm.

4. The optical fiber of claim 3, wherein the 2 m cable cutoff is from about 1140 nm to about 1200 nm.

5. The optical fiber of any one of claims 1 to 4, wherein the optical fiber has a 22 m cable cutoff of about 1060 nm to about 1200 nm.

6. The optical fiber according to any one of claims 1 to 5, wherein a one-meter length of the optical fiber has a maximum multipath interference of about -35 dB or less in the wavelength range of 1270 nm to 1330 nm.

7. The optical fiber of claim 6, wherein a one-meter length of the optical fiber has a maximum multipath interference of about -40 dB or less in the wavelength range of 1270 nm to 1330 nm.

8. The optical fiber of claim 7, wherein a one-meter length of the optical fiber has a maximum multipath interference of about -45 dB or less in the wavelength range of 1270 nm to 1330 nm.

9. The optical fiber according to any one of claims 1 to 8, wherein the value of α is greater than 5.

10. The optical fiber according to any one of claims 1 to 9, wherein the value of α is less than 12.

11. The optical fiber of any one of claims 1 to 10, wherein the mode field diameter at 1310 nm is 8.8 microns to about 9.2 microns.

12. The optical fiber of any one of claims 1 to 11, wherein r1 / r2 is greater than about 0.4 but less than about 0.

5.

13. The optical fiber according to any one of claims 1 to 12, wherein the maximum relative refractive index of the core region is about 0.28% to about 0.38%.

14. The optical fiber of Claim 13, wherein the maximum relative refractive index of the core region is from about 0.28% to about 0.36%.

15. The optical fiber according to any one of claims 1 to 14, wherein the trench volume is about -50% delta-micrometer 2 to about -30% Δ-μm 2 .

16. The optical fiber of Claim 15, wherein the trench volume is approximately -48% delta-micrometers 2 to about -32% Δ-μm 2 .

17. The optical fiber of any one of claims 1 to 16, wherein the core volume is about 4.5% delta-micron 2 to approximately 5.0% delta-micron 2 .

18. The optical fiber of any one of claims 1 to 17, wherein the outer radius r3 is from about 10 microns to about 18 microns.

19. The optical fiber of any one of claims 1 to 18, wherein the outer radius r3 is from about 12 microns to about 16 microns.

20. The optical fiber according to any one of claims 1 to 19, wherein the bending losses at 1310 nm determined by a mandrel winding test using a mandrel comprising a 15 mm diameter are less than 0.75 dB / turn.

21. The optical fiber of claim 20, wherein the bending losses at 1310 nm as determined by a mandrel winding test using a mandrel comprising a 15 mm diameter are less than 0.50 dB / turn.

22. The optical fiber of Claim 21, wherein the bending losses at 1310 nm as determined by a mandrel winding test using a mandrel comprising a 15 mm diameter are less than 0.40 dB / turn.

23. The optical fiber of Claim 22, wherein the bending losses at 1310 nm as determined by a mandrel winding test using a mandrel comprising a 15 mm diameter are less than 0.20 dB / turn.

24. The optical fiber according to any one of claims 1 to 23, wherein the bending losses at 1550 nm as determined by a mandrel winding test performed using a mandrel comprising a 15 mm diameter are less than 2.0 dB / turn.

25. The optical fiber of Claim 24, wherein the bending losses at 1550 nm as determined by a mandrel winding test using a mandrel comprising a 15 mm diameter are less than 1.5 dB / turn.

26. The optical fiber according to any one of claims 1 to 25, wherein the optical fiber has a MAC value at 1550 nm of about 6.0 to about 8.

0.

27. The optical fiber of Claim 25, wherein the MAC value at 1550 nm is from about 6.2 to about 7.

8.

28. An integrated system comprising The optical fiber according to any one of claims 1 to 27; and One or more vertical cavity surface emitting lasers (VCSELs) optically coupled to the optical fiber and emitting light at a wavelength between 980 nm and 1080 nm.

29. An integrated system comprising The optical fiber according to any one of claims 1 to 27; and One or more lasers optically coupled to the optical fiber and emitting light at one or more wavelengths between 1260 nm and 1360 nm.

Images