TW401519B - Distributed flat optical fiber - Google Patents

Abstract

A dispersion flat optical fiber is provided, which applies for the wavelength multiplex soliton transmission using an optical amplifier and the like and equips with the structure to effectively inhibit the appearance of nonlinear optical phenomena. The dispersion flat optical fiber of this invention is characterized in the following properties at a wavelength of 1550 nm: the absolute value of dispersion is below 5ps/nm/km; the effective cross section area is larger than 45 mu m<2> ; the dispersion slope is below 0.03; and the cutoff wavelength at a length of 2 m is above 1.0 mu m.

Description

Chinese patent application amendment page (February 89) V. Description of the invention-(View)

Printed by the Consumer Standards Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs. Cladding area 301 First cladding 302 Second cladding 510 Index side view 511,512,513,514,515 Field 520 Index side view 521,522,523,524,525 Field 530 Index side view 53 1,532,533,534,535 Field 540 Index side view 541,542,543,544,545 Field 600 Core field 601 First core field 602 The second core area 603 The third core area 700 The cladding area 701 The first cladding 702 The second cladding-33a- nn I 1 ^ 1 n II-^^-^ II Ding Yi 0¾ i Read · (Please read first Note on the back, please fill out this page again) This paper size is applicable to Chinese National Standard (CNS) A4 specification (210X297 mm) 401519 A7 B7 Printed by the Consumers' Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs • ^, Description of invention (1) tg month field This invention is related to the use of fiber optic networks Dispersion leveling of communication systems. The communication system (optical network) formed by the optical fiber network can be long-distance and large-capacity communication, and even use time-sharing operation multiplex transmission and wavelength multiplex soliton transmission to achieve large capacity (for example, refer to N. Edagawa , et al., &quot; Long distance soliton WDM transmission using a dispersion-flattened fiber &quot;, OFC, 97, PD19). In addition, such an optical communication system is composed of: a high-performance dual-use transceiver capable of receiving and emitting light waves signals; an optical amplifier capable of amplifying light wave signals; and an optical fiber transmitting light wave signals. Here, in order to obtain a high S / N ratio, an optical amplifier is indispensable, because the wavelength bandwidth of the optical amplification is 1530 nm ~ 1560 nm, and the wavelength of the available optical signal is essentially limited to a wavelength bandwidth of 30 nm. Inside. In an optical communication system using an optical amplifier, because the intensity of a light wave signal in an optical fiber becomes stronger, a non-linear optical phenomenon such as 4 light wave mixing, self-phase modulation, and the like occurs in the optical fiber. Here, regarding 4-wave mixing, if the dispersion of the wavelength of the light signal is absolutely at a level of 1 ps / nm / km to 5 ps / nm / km ', its occurrence can be suppressed. On the other hand, with regard to the interaction between phase modulation and wavelength dispersion (hereinafter referred to as dispersion), the transmission of solitons in a single-wavelength light wave signal is no problem, while multiple-wavelength multiplexed light wave signals are transmitted. There are the following problems. That is, a dispersion-shifted fiber capable of shifting zero-dispersion wavelengths around a wavelength of 550 nm, because it usually has a wave paper scale of about 0.07 ps / nm2 / km (picoseconds / square nanometer / km). Applicable to Chinese National Standards (CNS) Α4 specifications (210 × 297 male f) j --------- installed-(Please read the precautions on the back first ^^ write this page) Order-spring. 0 4 (M519 Α7 ___._____ B7 V. Description of the invention (2) The long-dispersion (hereinafter referred to as dispersion slope) printed by the Central Laboratories of the Ministry of Economic Affairs, Shellfish Consumer Cooperative, each transmitted light wave signal wave I, has a different dispersion 値. Therefore Will destroy the balance with its own phase modulation, which will destroy the light wave signal pulse (puUe). Therefore, in this case, a dispersion leveling fiber with a very small dispersion slope is required. Also, if the fiber is not The linear refractive index is N2, the effective cross-sectional area is Aeff, the light wave signal power (powtr) is P, and the effective length of the fiber is. The nonlinear optical phenomenon generated by the fiber is shown by the following formula (1): N2 · P * Leff / Aeff… (1) In order not to make wrong It is necessary to increase the power of the optical wave signal to obtain a high S / N ratio, and increase the effective optical cross-sectional area. It is necessary to increase the effective cross-sectional area octaval. In addition, when operating multiplexed transmission at a single wavelength, it is necessary to suppress non-linearity. The optical phenomenon not only makes the effective cross-sectional area larger, but the absolute dispersion is also below 1 ps / nm / km. Furthermore, it is necessary to make the dispersion slope extremely small. Even when it is used to suppress the fiber optic cable The loss increases, and it is required to reduce the bending loss. Therefore, the cutoff wavelength must be set at an appropriate value. The above-mentioned nonlinear refractive index N 2 is defined as the following. That is, the medium under strong light The refractive index N is changed by the optical power. Therefore, the lowest order effect with respect to the refractive index is expressed by the following formula (2). Ν = Ν0 + Ν2 · E2 ... (2) Here, NO: Refractive index for linear polarization N2: Non-linear refractive index for 3rd-order non-linear polarization E: is the amplitude of the optical electric field ——: -------- install-- 、 / (please first I read the note on the back of the page and write this page) Order | 6_ 5--II Standard (CNS) Λ4 specification (2 丨 0X297) i-Printed by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs 40.1519 A7 ________B7 V. Description of the invention (3) In strong light, the refractive index N of the medium is generally 値 N〇 and and The sum of the proportional increase of the second power of the optical electric field amplitude E. In particular, the proportional parameter N2 (unit: m2 / V2) of the second term is called a non-linear refractive index. The effective cross-sectional area Aeff described above is As shown in Japanese Patent Application Laid-Open No. 8_248251, it is expressed by the following formula (3). 〇〇 09

Aeff = 27T (1e rdr) 2 / (Ιε4γ &lt; 1γ) ... (3) ο 〇 However, E is an electric field accompanying propagation light, and r is a radial distance from the center of the core. The dispersion slope is defined by the slope of the dispersion characteristic in a predetermined wavelength band as shown in the figure. The inventors reviewed the results of the conventional dispersion leveling optical fiber, and found the following problems. That is, in the conventional dispersion correction fiber, the dispersion slope is very small, and because the effective cross-sectional area is not only about 30 &quot; m2 ~ 40 # m2, the optical power density in the core area is also very high, which is very easy to occur. Non-linear optical phenomena such as 4 light wave mixing. Therefore, the conventional dispersion leveling optical fiber is not suitable for a wavelength multiplexed optical communication system using an optical amplifier. For example, M. Ohashi, et al., &Quot; Dispersion-modified Single-Mode Fiber by VAD Method with Low Dispersion in 1,5 &quot; The 1.5 &quot; m Wavelength Region &quot;, ECOC'88, pp.455-448 describes the dispersion flattened optical fiber, which has the following: the core (core) (the first core); Bao Yuan should The second core of the center core; it is enclosed by the -6-I 1-(锖 read the precautions on the back ^; write this page)., Νβ —ό_ This paper size applies the Chinese National Standard (CNS) Λ4 specifications ( 210X297 公 # 1 &quot; Printed by the Central Standards Bureau of the Ministry of Economic Affairs, Shellfish Consumer Cooperative, A7 _B7___ V. Description of the invention (4) The core area formed by the third core of the second core; and the clad containing the core area And has the following triple clad type refractive index profile: by adding a germanium (Ge) element to the central core (the first core), the Relative refractive index difference to 0.87%; by the 2nd core Adding fluorine (F) element to reduce the relative refractive index difference to the second core area of the cladding area to -0.41%; moreover, by adding germanium (Ge) element to the third core, the The relative refractive index difference of the third core is 0.23%. Also, in the conventional dispersion-leveling fiber, the dispersion slope of the wavelength of 1550 nm (nanometer) is 0.023 ps / nm2 / km. The effective cross-sectional area is not only at 37 &quot; m2 degree. Also, Y. Kubo, et al., &Quot; Dispersion Flattened Single-Mode Fiber for 10,000km Transmission System &quot;;, ECOC, 90, pp.505-508 The dispersion leveling optical fiber has the following: a central core; a core area composed of a second core surrounding the central core; and a cladding surrounding the core area And also has the following W-shaped refractive index side view: by adding a germanium (Ge) element to the central core, the relative refractive index difference of the central core area relative to the cladding is increased to 0.9%; Adding fluorine (F) element to the second core area to reduce relative The cladding layer of the second core relative to the refractive index difference of -0.4%. Also, even with the conventional dispersion-leveling optical fiber, the dispersion slope at a wavelength of 1550 nm is 0.023 ps / mn2 / km, and the effective cross-sectional area of the fiber is below 30 millimeters ^. On the other hand, the effective cross-sectional area of a general dispersion-shifted fiber is 50 (please read the notes on the back first ^^ write this page) Chinese National Standard (CNS) A4 Regulation (210/297 ^ 1 ^ ^ 0Ϊ5ί9 V. Description of Invention (5) // m2 degree, which is the larger one, and because the dispersion slope is at 0〇7 ps / nm2 / km The effect of dispersion on dispersion is very large, and it is also not suitable for long-distance optical transmission (for example, reference, γ Terasawa, et al &quot; Design of dispersion-shifted fiber with amplified mode field diameter for WD] ^ transmission It is predicted that Design Optimization of Dispersion Shifted Fiber with Enlarged Mode Field Diameter for WDM Transmission &quot;, IOOC.95, FA2_2). Therefore, any conventional optical fiber is not suitable for multiplexing transmission and wavelength with time division operation using optical amplifiers. The present invention is an inventor for solving the above-mentioned problems. The object of the present invention is to provide a dispersion leveling optical fiber. The dispersion leveling optical fiber is provided with: time-division operation multiplexing suitable for an optical communication system including an optical amplifier. Teleport and The structure of long multiplexed soliton transmission. In order to achieve the above-mentioned purpose, the dispersion leveling optical fiber related to the present invention has various characteristics of the center wavelength of 1550 nm in the following wavelength band (1500 nm to 600 nm): Absolute Dispersion below 5 ps / nm / km 'Effective cross-sectional area above 50; dispersion slope below 0.02 ps / nm2 / km; and cut-off wavelength above 1.0 m in length of 2 meters. Central standard of the Ministry of Economic Affairs The staff of the Bureau ’s Consumer Cooperative Co., Ltd. ’s dispersion leveling fiber ’s absolute dispersion at a wavelength of 155nm is below 5 pS / nm / km, and because the dispersion slope is below 〇02 ps / nm2 / km. The dispersion difference between the light wave signals becomes smaller. In addition, because the effective cross-sectional area is above 50 &quot; m2, the power density of the light wave signal is suppressed by the dispersion leveling optical fiber to suppress propagation. This can effectively suppress The occurrence of non-linear light phenomenon makes it possible to transmit with high S / N ratio. Even ______ -8- This paper size is suitable for papers and counties s> A4 ^ (21GX297, &gt; vy ^-Central Ministry of Economic Affairs A7, Department of Consumer Cooperatives, Standards Bureau --------- -B7 V. Invention Description (6) ~ The dispersion leveling optical fiber has good bending characteristics. Also, in order to effectively suppress the occurrence of non-linear optical phenomena, as mentioned above, the effective cross-sectional area is 50 // m2 Above, it is necessary to be more than 70%, and an increase in the effective cross-sectional area of the child will lead to an increase in bending loss. Increasing such a bending loss is not a good phenomenon for the cable of the dispersion-leveling optical fiber. On the other hand, suppression of nonlinear optical phenomena is achieved by generating desired dispersion in the dispersion-leveling optical fiber. Therefore, the dispersion-leveling optical fiber related to the present invention can be realized: the effective cross-sectional area is above 45 &quot; m2, and the dispersion slope is 0.003ps / nm2 / km, as a good relationship between the effective cross-sectional area and the dispersion slope. . The dispersion leveling optical fiber having various characteristics as described above is realized by the following structure (ring core structure, ring core): a first core having a predetermined refractive index; and a second core provided in the The outer periphery of the first core has a higher emissivity than the first core. In addition, the above-mentioned core area may have the following structure (three-layer core structure): a first core having a predetermined refractive index; and a second core provided on the outer periphery of the j-th core and having a lower core than the first core. The refractive index; and the third core is provided on the outer periphery of the second core and has a higher refractive index than the second core. The above-mentioned cladding area may also have a depressed clad structure: a first cladding (inner cladding) provided on the outer periphery of the core area; and a second cladding (outer cladding) Is provided on the outer periphery of the first cladding layer and has a higher refractive index than the first cladding layer. The dispersion cladding fiber can also be realized by combining the flat cladding structure by the above-mentioned ring core structure and any three-layer core structure. -9- This paper size applies to Chinese National Standard (CNS) Λ4 specification (210X297 ^^) J ^-T (Please read the notes on the back * item ^; write this page) I-Order Miscellaneous A7- -B7 V. Description of the invention (7) J --------- Pack 17 (please read the note t on the back ^^ write this page) or even 'equipped with the above-mentioned ring core structure and section (segmem ) Structured dispersion-leveling fiber with various characteristics mentioned above, when practically considered as a transmission path, it has various characteristics with a wavelength of 550 nm, and preferably further has 0.15 ps / kmi / 2 (pico Seconds / root kilometers) polarization wave dispersion below. Furthermore, if fiber optic cable is considered, the transmission loss of this dispersion-leveling optical fiber when it is bent to a diameter of 32 mm (cm) is preferably 0-5 dB / turn (decibel / turn). Especially, the transmission loss In the core structure of the layer, the cut-off wavelength at a length of 2 meters is preferably above ^^. These inventors also found that the dispersion leveling fiber in the above-mentioned three-layer core structure reduces the dispersion slope, and at the same time, increases the cut-off wavelength to reduce bending loss, and greatly contributes to the above-mentioned third core. That is, in a dispersion-leveling optical fiber having a three-layer core structure, the second core outer diameter is b, the third core outer diameter is c, and the third core relative refractive index difference with respect to the reference field of the cladding field is Δη3. It is best to satisfy the following relationships. Δη3 ^ 0.25% 0.40Sb / c including 0.75 d. In other words, the Central Consumers Bureau of the Ministry of Economic Affairs's Consumer Cooperatives Co., Ltd. In other words, the profile volume of the third core is r in the radius from the center of the core area, and When the relative refractive index difference of the distance r portion with respect to the reference area of the cladding area is Δη (r), it is preferable to satisfy the following conditions. c / 2

Saii (r) rdr ^ 7. 0 (% · // m2) b / 2 The cladding area is preferably the flat cladding structure described above. At this time, in order to -10- this paper size applies the Chinese National Standard (CNS) A4 specification (210X297 public reference) printed by the Consumer Cooperatives of the Central Procurement Bureau of the Ministry of Economic Affairs 4015 »A7 .__ B7 J ^ · --- _____ V. Description of the invention (8) The reference field that defines the relative refractive index difference of each glass field is the 2 cladding. The dispersion leveling optical fiber is constructed by combining a three-layer core structure and a flat cladding structure. The first core outer diameter is a, the second core outer diameter is b, and the third core outer diameter is c. When the first core relative refractive index difference is Δηι and the first cladding relative refractive index difference with respect to the second cladding is, the following relationship is preferably satisfied. 0.40% ^ Δηι S0.90% Δη4 ^ -0.02% 0.20 ^ a / c ^ 0.35 20 ^ m ^ c ^ 3〇A &m; plus' if manufacturing errors are taken into consideration, the dispersion-leveling optical fiber related to the present invention , Must be designed to tolerate related manufacturing errors. Specifically, a manufacturing error of about 2% of the outer diameter of the core area is generated between the manufactured lots (the outer diameter can only be controlled to about 2%). Therefore, in the dispersion-leveling optical fiber related to the present invention, it is necessary to limit the variation in the dispersion slope due to the variation in characteristics caused by the variation in the outer diameter of the core area. If, through experiments by these inventors, the dispersion slope 値 decreases as the outer diameter of the core area increases, it is even understood that there is a tendency to increase as the outer diameter of the core area increases.値, the dispersion slope is minimized 値). Therefore, in the dispersion leveling optical fiber related to the present invention, in order to suppress the variation in characteristics caused by manufacturing errors, the outer diameter is within the range of ± 2% centered on the core area with the dispersion slope of the dispersion leveling fiber having a very small chirp. Inside, to set the outer diameter of the core area. In detail '相 -11-This paper size is applicable to the Chinese National Standard (CNS) Λ4 specification (210X297 ^,) ----------- installation-: (Please read the notes on the back first ^ Write this page) Order • II mm A7

Du Yinzha, Cooperator of Consumers, Central Bureau of Standards, Ministry of Economic Affairs. 5. Description of the Invention (9) For the design 値, when the outer diameter variation range of the core area is ± 2%, the variation of the dispersion slope is suppressed below 0.003 ps / nm2 / km. . Brief Description of the M Diagram FIG. 1A is a cross-sectional structure diagram of a dispersion-leveling optical fiber illustrating a core structure of a shape related to the present invention. Fig. 1B is a side view of the refractive index shown along a line L1 in Fig. 1A. Fig. 2 is a graph showing the dispersion characteristics of a dispersion-leveling optical fiber related to Embodiment 1 ', and this Embodiment 1 is a side view having a refractive index shown in Fig. 1B. Fig. 3 is a side view of the refractive index of a dispersion-leveling optical fiber according to Example 2 (ring core structure + flat cladding structure) of the present invention. Fig. 4 is a graph showing the dispersion characteristics of a dispersion-leveling optical fiber according to Embodiment 2, which is a side view having the refractive index shown in Fig. 3; Fig. 5A is a cross-sectional structural view of a dispersion-leveling optical fiber showing a three-layer core structure related to the present invention, and Fig. 5B is a refractive index side view taken along line L2 in Fig. 5A. FIG. 6 is a dispersion characteristic diagram illustrating a dispersion leveling optical fiber related to Example 3 (three-layer core structure + flat cladding structure), and Embodiment 3 is a side view having the refractive index shown in FIG. 5B *. Fig. 7 is a side view of the refractive index of a dispersion-leveling optical fiber related to Example 4 (three-layer core structure) of the present invention. Fig. 8 is a graph showing the dispersion characteristics of a dispersion-leveling optical fiber according to Example 4, which is a side view having the refractive index shown in Fig. 7. Fig. 9 is a table showing various characteristics of the dispersion-leveling optical fibers related to the first to fourth embodiments. -12- I -------- ^-. (Please read the notes on the back • Item C to write this page) l · Order—line 0 thousand I k ϊ r Inspection ^ Central Standards Bureau of the Ministry of Economic Affairs Industrial and Consumer Cooperatives Co., Ltd. A7 B7 V. Description of the Invention (10) ~ Figure 10 is to prepare sample 5 with the refractive index side view of Figure 56 and to focus on the outside diameter of the third core of samples 1 to 5 Table of measurement results of the second core outer diameter ratio (b2 / c2) and the relative refractive index difference (Δη3) with respect to the third core of the second cladding (outer cladding). FIG. 11A and FIG. 11B show changes in the dispersion slope (ps / nm2 / km) with respect to the outer diameter of the core area (the third core outer diameter 〇2) in samples 1 to 5 'having the refractive index side view of FIG. 53. Illustration. FIG. 12A and FIG. 12B are graphs showing changes in cutoff wavelength (// m) with respect to the outer diameter of the core area (the third core outer diameter c 2) in samples 1 to 5 ′ having the refractive index side views of FIG. 5B . 13A to 13C are modification examples of the refractive index side view (refractive index side view) of FIG. 5B. Fig. 14 'is a table showing the results of various characteristics measured on samples 6 to 8 having various refractive index side views shown in Figs. 13A to 13C. 15A to 15D show samples 7 having the refractive index side views shown in Fig. 13B. In this sample 7, there are various characteristic change tables showing changes with respect to the outer diameter of the core area (the third core outer diameter c 2), and FIG. 15A shows the outer diameter of the core area (A m) and the effective cross-sectional area (&quot; m2), FIG. 15B is a graph showing the relationship between the bending loss (dB / m) when the outer diameter of the core area (sound m) is bent with a diameter of 20 mm, and FIG. 15C is a graph showing the outer diameter (jum) and dispersion of the core area The relationship of the slope (ps / nm2km), FIG. 15D is a diagram illustrating the relationship between the outer diameter (&quot; m) and the dispersion (ps / nm / km) of the core area. Figure 16A and Figure 16B are sample 8 showing the relationship between the change in the outer diameter of the core area and the changes in various characteristics. Figure 16A is the chart showing the outer diameter of the core area and the color. -13- This paper applies Chinese national standards (CNS) A4 Regulations (210x297 male and 1 Ding (please read the notes on the back • items to write this page) -installation-Ding. 、 · = * Printed by the Consumers' Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 401519. A7 _________ ^ 5. Invention Explain (Ί1) the relationship between dispersion (ps / nm / km) and dispersion slope (ps / nm2 / km). Figure 16B is the variation of dispersion slope (ps / nm2 / km /%, picosecond / square nanometer / km / percent) relationship. Figure 17A is a table showing the relationship between the meandering radius (mm) and bending loss (dB / m), and Figure 17B is a diagram showing the fiber length (km ) And cut-off wavelength (#m). Figure 18 A, in samples 1 to 5, is the side volume (0/0. &Quot; m2, percentage. Square micrometer) and dispersion slope (ps) of the third core. / nm2 / kin) The relationship diagram 'Fig. 18B' in samples 1 to 5 'is a diagram showing the relationship between the side volume (%. // m2) of the third core and the cut-off wavelength (# m) In order to implement the best method of the present invention, the following processes are performed using FIG. 1A, FIG. 1B, FIG. 2 to FIG. 4, FIG. 5A, FIG. 5B, FIG. 6 to FIG. 10, FIG. 11A to FIG. 13C, FIG. FIG. 18B illustrates an embodiment of the dispersion leveling optical fiber related to the present invention. In addition, the same important parts are denoted by the same symbols in the drawing to omit repeated description. The dispersion leveling optical fiber related to the present invention is applicable to Long-distance submarine cables, etc. are also used to propagate one or two types of optical wave signals in the 1.55 &quot; m wavelength band (with a central wavelength or two or more types of optical wave signals in the range of 1500 nm to 1600 nm). Dream system single mode (single mode) fiber. In addition, the dispersion leveling fiber is provided with: a core area extending along a predetermined axis; and a cladding area provided on the outer periphery of the core area. In the signal wavelength band 1.55 & quot The m-wavelength band is designed with a decreasing dispersion slope, and it is necessary to reduce the dispersion error between the transmitted light wave signals. In particular, the dispersion-leveling optical fiber related to the present invention has the following as Various characteristics at a wavelength of 1550 nm: Confrontation at 5 ps / nm / km -14- This paper scales thorns® Caixian (CNS> Ege (2ΐΟχ297ϋ! (Please read the notes on the back first, write this page))-Pack · Ή. I · order --.--- r. Printed by the Central Bureau of Standards of the Ministry of Economy—Industrial and Consumer Cooperatives 401519 A7 A7 __ · _B7 V. Dispersion of the invention (12) or less; Effective cross-sectional area is above 45 # m2, preferably Above 50 m2, and preferably above 70 m2, the dispersion slope is below 0.003 ps / nm2 / km, preferably below 0.02 ps / nm2 / km; and the cutoff wavelength is between More than 1.0 // m in length of 2 meters. Furthermore, the dispersion leveling optical fiber related to the present invention preferably has the following characteristics as the wavelength of 1550 nm. Polarized wave dispersion is preferably 0.15 ps / km1 / 2 or less; The transmission loss when bent to a diameter of 32 mm is preferably below 0.5 dB / turn. In addition, the above-mentioned transmission loss is measured on a mandrel with a diameter of 32 mm for a plurality of times, and the transmission loss of the optical fiber listed as a measurement object is measured in a curled state, and the transmission loss is converted into a equivalent of one turn. The following is simply referred to as bending loss. As a structure for realizing the above-mentioned various characteristics, a core area extending along a predetermined axis is preferably a ring-shaped core structure having the following cores: a first core having a predetermined refractive index; and a second core provided on an outer periphery of the first core. And has a higher refractive index than the first core. It is also possible to have a three-layer core structure with the following cores: a first core with a predetermined refractive index; a second core, which is located on the outer periphery of the first core and has a lower refractive index than the first core; The third core is located on the outer periphery of the second core and has a lower refractive index than the first core. In the case of a three-layer core structure, the cut-off wavelength at a length of 2 meters must be 1.4 &quot; m or more. In addition, the cladding area provided on the outer periphery of the core area may be a flat cladding structure having the following claddings: a first cladding (inner cladding) provided on the outer periphery of the core area, and a second cladding. It is provided on the outer periphery of the first cladding layer and has a higher refractive index than the first cladding layer. -15-

This paper size applies to the Chinese National Ladder &lt; CNS) Λ4 ^ grid (2l0X 297々TT) installed-'(Please read the notes on the back first to write this page) I Ding. &Quot; $ Staff of Central Bureau of Standards, Ministry of Economic Affairs Printed by a consumer cooperative 401519 A7 _________B7___ 5. Description of the invention (13) Especially in a dispersion leveling optical fiber with a 3-layer core structure, the outer diameter of the second core is b, and the outer grip of the third core is ^. When the relative refractive index difference of the third core in the reference field (second cladding in the flat cladding structure) is Δη3, it is preferable to satisfy the following relationship: Δη3 ^ 0.25% 0.40Sb / cS0.75 Therefore, the third core When the lateral volume is r from the center of the core area in the radial direction, and the relative refractive index difference from the reference area of the cladding area is An (r) from the center, it is better to satisfy the following C / 2 5δπ (γ) rdr ^ 7. 0 (% · um2) b / 2 or even 'composed of a dispersion-shifted fiber by combining a 3-layer core structure and a flat cladding structure, outside the first core Diameter is a, 2nd core outer diameter is & 3rd core outer diameter is c, 1st with respect to 2nd cladding When the relative refractive index difference of the core is Δηι and the relative refractive index difference of the first cladding layer with respect to the second cladding layer is Δ ^^, it is preferable to satisfy the following relationship: 0 40% SAni ^ 0.90% Δη4δ-〇.02 〇 / 0 〇-20sa / cS0.35 2〇 ^ msc ^ 3〇A &lt; m and the relative refractive index difference of each field with respect to the reference field of the cladding field is expressed by the following formula (4). ___ -16- This paper size is suitable for wealth Hi] Home materials. (CNS) Ba 4 Na (MGx297 male p '~~ --_ J -------- t—— (Please read the note on the back first) Matters written on this page j-order 4 '·' 〇A7 137 401519 V. Description of the invention (Η) (nT-nR) / nR… (4) Here 'ητ 疋 is the refractive index of the glass field, Refer to the refractive index of the cladding field (also, when the cladding field is in the flat cladding structure, it is the refractive index of the second cladding layer) ^ In this specification, the relative refractive index difference of each glass field is in angular minutes. For example, each parameter in formula (4) does not change in order. Therefore, the relative refractive index represented by minus 値 has the following meaning: it has a refractive index lower than the reference field In addition, 'the outer diameter of the core area is preferably centered on the dispersion when the dispersion slope becomes extremely small', within a range of ± 2%. Specifically, these inventors discovered that in order to make manufacturing errors, The dispersion slope variation with respect to the ± 2% variation of the outer diameter of the core area is preferably designed to be less than 0.003 ps / nm2 / km. The following 'i' will sequentially describe embodiments of the dispersion leveling optical fiber related to the present invention. Also, the dispersion leveling optical fiber related to the first and second embodiments described below is a core area having a ring core structure and a cladding area having a flat cladding structure, respectively. The dispersion leveling optical fiber according to the third embodiment is a core area having a three-layer core structure and a cladding area having a flat cladding structure. Furthermore, the dispersion-leveling optical fiber related to Embodiment 4 is a core field having a three-layer core structure and a single-layer cladding field. Embodiment 1 First, FIG. 1A is a cross-sectional structure view illustrating a dispersion leveling optical fiber related to Embodiment}, and FIG. 1B is a refractive index side view taken along line L1 in FIG. 1A. Also 'line L 1 is based on the central axis point showing the dispersion leveling fiber 丨 〇〇 -17-

This paper size applies the Chinese National Standard (CNS) Λ4 Regulation (210x 297, is ^ &quot; T —.-------- Crack — (诮 Read the precautions on the back first ^ sfsi? This page)-Order -Line- 〇 Printed by the Central Standards Bureau of the Ministry of Economic Affairs, Consumer Cooperatives, Printed by the Central Standards Bureau of the Ministry of Economic Affairs, printed by the Shellfish Consumer Cooperatives, 401519 .., A7 B7 _ 1 .. — — * &quot; &quot;-— ___ V. Description of the invention (15) The line of intersection. The dispersion leveling optical fiber 100 related to the first embodiment is provided with: a core area 200 of a ring core structure; and a cladding area 300 of a flat cladding structure. The above core area 200 is The first core 201 has an outer diameter a 1 having a refractive index η; and the second core 202 is an outer diameter provided on the outer periphery of the first core 201 and having a refractive index η2 (&gt; ηι). bl. Also, the above-mentioned cladding area 300 is provided with: a first cladding 301, which is provided on the outer periphery of the second core 202, and has an outer diameter c 1 having a refractive index η3 (= πι); and a second cladding The layer 302 is provided on the outer periphery of the first cladding layer 301 and has a refractive index n4 (&gt; η3). Here, the refractive index side view 150 of FIG. The refractive index of the various areas of the line L1 in α, the area 15ι is equal to each part on the line L 1 of the first core 201, and the area 152 is equal to each part on the line L 1 of the second core 202. 'field 153 The areas 154 equal to the respective parts on the line Li of the first cladding 3301 are equal to the parts on the line 11 of the second cladding 302. In the first embodiment, the second cladding 302 (Reference area of cladding area 300) The relative refractive index difference Any of the first core 201 and the relative refractive index difference Any of the j-th cladding layer 301 are _〇6%, which is 3% relative to the second cladding layer 3. The relative refractive index difference Δη2 of the second core 〇2 is 〇7%. The outer diameter al of the i-th core 201 is 3.04 ^, and the second core 2b is held outside the bm2 "m, the first cladding 301 (outer diameter &lt;: 1 is 13 2), after the dispersion leveling optical fiber is outside 100 (outer diameter of the second cladding 302) is 125 ... and the relative refractive index difference in each field is as follows Δηι = (η1-η4) / η4 _ -18- This paper size applies to Chinese national standards ((Please read the precautions on the back first to consume this page) -Packing--J-^ Order by the Central Bureau of Standards of the Ministry of Economic Affairs Consumer and Consumer Cooperatives, India 4 01519 A7 ____B7 V. Description of the invention (16) △ η 2 = (H2_ 114) / 114 Δη3 = (η3-η4) / η4 These inventors measured various characteristics of dispersion leveling fiber 100 at a wavelength of 1550 nm, and the dispersion correction The flat optical fiber is related to the first embodiment constructed as described above. As a result, the dispersion chirp at a wavelength of 1550 nm is 0.17 ps / nm / km (&lt; I 5 I ps / nm / km), and the effective cross-sectional area Aeff at a wavelength of 1550 nm is 58 &quot; m2 (&gt; 45 &quot; 1112) The cut-off wavelength at a length of 2 meters is 1.153 &quot; 111 (&gt; 1.0 &quot; 111). The 'dispersion slope' is 0.018 ps / nm2 / km at 1530 nm, 0.007 ps / nm2 / km (&lt; 0.03 ps / nm2 / km) at 1550 nm, and 0.000 ps / nm2 / km at 1560 nm. . Furthermore, the polarization dispersion at a wavelength of 1550 nm is 0.11 ps / km1 / 2 (&lt; 0.15 ps / km1 / 2). Fig. 2 is a graph showing the dispersion characteristics of the dispersion-leveling optical fiber 100 according to the first embodiment. Embodiment 2 Fig. 3 is a side view of the refractive index of a dispersion-leveling optical fiber according to Embodiment 2 of the present invention. The cross-sectional structure of the dispersion leveling optical fiber of the second embodiment is the same as that shown in Fig. 1A. Therefore, the refractive index profile 160 is equal to the refractive index of each area along the line L 1 in FIG. 1A, and the area 161 is each part equal to the line L 1 of the first core 201, and the area 162 is equal to For each part on the line L1 of the second core 202, the area 163 is equal to each part on the line L1 of the first cladding 301, and the area 164 is equal to each part on the line L1 of the second cladding 302. In the second embodiment, the outer core al equal to the first core (refractive index η) in the field 161 is 3.75 &quot; m, and the second core equal to the domain M2 (refractive index ~: ^) and the outer diameter bl is 8.25 &quot; m, It is equal to the first cladding (refractive index !! 3 = 111) of field 163. The outer diameter is -19- This paper rule _ degree applies Chinese National Standard (CNS) Λ4 regulation (210X 297 / &gt; H --- J.- ------- Crack--1 (Please read the notes on the back first to write this page) I Ding,-= 3 —ά Central Government Bureau of Standards, Ministry of Economic Affairs, Shellfish Consumer Cooperatives Co., Ltd. 401519 ΑΊ I ----- --- B7 V. Description of the invention (17) — ~~ cl is 15.0 &quot; m, and the outer diameter of the second cladding (refractive index ~> ^) equal to field 164 is 125. Moreover, compared with the second cladding, The relative refractive index difference Δϋ! Of the first core (= (ηι-η4) / η4) and the relative refractive index difference of the first cladding layer are collectively -0.60%, and the relative refraction of the second core with respect to the second cladding layer The rate difference An2 (= (n2-n4) / n4) is 6.3%. These inventors measured various characteristics of the dispersion-leveling optical fiber at a wavelength of 1550 nm, and the dispersion-leveling optical fiber is an embodiment constructed as described above. As a result, the dispersion at a wavelength of 1550 nm is 値 12. ps / nm / km (&lt; 丨 5 | ps / nm / km), effective cross-sectional area Aefm &quot; m2 (&gt; 45 &quot; m2) at a wavelength of 1550 nm, i 187 &quot; m at a cut-off wavelength of 2 meters (&gt; ι〇 &quot; is called. Also, the dispersion slope is 0.0096 ps / nm2 / km at a wavelength of 1530 nm and -0.0120 ps / nm2 / km at a wavelength of 1550 nm (&lt; 0.03 ps / nm2 / km), at a wavelength of 1560 nm is -0.0205 ps / nm2 / km. Furthermore, the polarization dispersion at a wavelength of 1550 nm is 0.10 卩 8 / 1〇111 / 2 (&lt; 0.15? 8 / 1〇 | 11/2). Also, FIG. 4 is a diagram showing the dispersion characteristics of a dispersion leveling optical fiber related to the second embodiment. Embodiment 3 FIG. 5A is a cross-sectional structure diagram showing a dispersion leveling optical fiber related to the third embodiment 'FIG. 5B is a side view of the refractive index shown along line L2 in FIG. 5A. Also, line' L2 'is a line which crosses by drawing a point θ2 at the center of the dispersion leveling optical fiber 500 at tf. The dispersion leveling optical fiber 500 related to the third embodiment is a core area 600 having a three-layer core structure and a cladding area 700 having a flat cladding structure. The core area 600 described above is provided with: 6〇ι, is the outer diameter a2 with a refractive index η; the second core The core 602 is an outer diameter b 2 provided on the outer periphery of the first core 601 and having a refractive index η2 (<η!); And the third core -20- This paper applies the Chinese National Standard (CNS) Λ4 rule Nuclear (210X297 public records) ---------- t--1 (Please read the notes on the back f to write this page) • J --- Order—Line 0 Staff Consumption of Central Bureau of Standards, Ministry of Economic Affairs Cooperative Du printed 401519 ^ A7 B7 V. Description of the invention (18) The heart 603 is located on the periphery of the second core 602. And has an outer diameter c2 of a refractive index n3 (&gt; n2). In addition, the above-mentioned cladding area 700 is provided with a first cladding 701, an outer diameter c2 provided on the outer periphery of the third core 603 and having a refractive index n4 (&lt;n3); and a second cladding 701 Is provided on the outer periphery of the first cladding layer 701. And has a refractive index of 115 (&gt; 114). Here, the refractive index side view 510 of FIG. 5B illustrates the refractive index of each area along the line L2 in FIG. 5A, the area 511 is equal to each part on the line L2 of the first core 601, and the area 512 is equal to the first For each part on line L2 of core 2 602, field 513 is equal to each part on line L2 of core 3 603, field 514 is equal to each part on line L2 of first cladding 701, and field 515 is equal to second Various parts on the line L2 of the cladding 702. In this Example 3, the relative refractive index difference 第 of the first core 601 with respect to the second cladding 702 (reference area of the cladding field 700) is 0.58%, and with respect to the second core 602 of the second cladding 702 The relative refractive index difference 厶 112 is -0.10%, the relative refractive index Δη3 with respect to the third core 603 of the second cladding 702 is 0.40%, and the relative refractive index with respect to the first cladding 701 of the second cladding 702 The difference Δη4 was -0.27%. The outer diameter a2 of the first core 601 is 5.8 &quot; m, the outer diameter b2 of the second core 602 is 16.2 &quot; m, the outer diameter of the third core 603 is 23.2 &quot; m, and the first cladding 701 is The outer diameter d is 46.4 // m, and the outer diameter of the dispersion leveling optical fiber 500 (the outer diameter of the second cladding 702) is 125 &quot; m. The relative refractive index difference in each field is as follows. Δη1 = (η1-η5) / η5 △ η2 = (η2-η5) / η5 △ η3 = (η3-η5) / η5 __________-21-Paper size 剌 ㈣8) Jiaxian (CNS) Λ4 test (2) ( ) &gt; &297; 297 ^^ ~ '--J -------- install --M (please read the precautions on the back first! ^ write this page) —ir —d 401519 A7 B7 five Description of the invention (19) Δη4 = (η4-ιΐ5) / η5 These inventors measure various characteristics of the wavelength of the dispersion leveling optical fiber 500, which is 55nm, and the dispersion leveling optical fiber 500 is as above The structure is related to Example 3. As a result, the dispersion at a wavelength of 1550 nm is _2 2 ps / nm / km (&lt; | 5 | ps / nm / km), and the effective cutoff at a wavelength of i55 nm area

Aeff is 50 // m2 (&gt; 45 &quot; m2), and the cutoff wavelength at a length of 2 meters is i92o &quot; m (&gt; 1.0 # m). The dispersion slope is 0 〇129 pS / nm2 / km at a wavelength of 1530 nm, and 〇172 ps / nm2 / km at a wavelength of 1550 nm (&lt; 〇03 ps / mn2 / km) at a wavelength of 1560. It is 0.0198 ps / nm2 / km. Furthermore, the polarization dispersion at a wavelength of 1550 nm is 〇6 ps / kml / 2 (&lt; 015 ps / km1 / 2). Fig. 6 is a graph showing a dispersion characteristic of a dispersion-leveling optical fiber according to the third embodiment. Embodiment 4 FIG. 7 is a side view of the refractive index of a dispersion-leveling optical fiber according to Embodiment 4 of the present invention. Also, the 'dispersion leveling optical fiber of Embodiment 4 is a core area having a three-layer core structure and a single-layer cladding area similar to the core area 600 of FIG. 5A', and its refractive index side view 17 is also referred to as a triple cladding Side view of the refractive index of the model.

The refractive index side view 170 is substantially equal to the refractive index of each area along the line L2 in FIG. 5A, and the area m is equal to the first! Each part on the line L 2 of the core 601, the field 172 is equal to each part on the line L 2 of the second core 602, the field 173 is equal to each part on the line L2 of the third core 603, and the field 174 is equal to Various parts on the line L2 of the second cladding layer 702. However, the dispersion leveling optical fiber of Example 4 does not exist as shown in Figures 5A -22- This paper size applies the Chinese National Standard (CNS) A4 Regulation (2 丨 0X297 male f) (Please read the note on the back first to write (This page), -β --_--- Ί

L Printed by the Consumers 'Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 401519 A7 B7 Printed by the Consumers' Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 5. Field 1 of the first envelope in the description of the invention (20). In the fourth embodiment, the outer diameter a2 of the first core (refractive index m) equal to the domain 171 is 7.3 // m, and the outer diameter b2 of the second core (refractive index η2 &gt; η) equal to the domain 172 is 15.0 &quot; m ' The outer diameter c2 of the third core (refractive index n3 = n2) equal to the domain 173 is 22.0 μm, and the outer diameter of the cladding (refractive index n4> n3) equal to the domain 174 is 125 am. The relative refractive index difference Δηι (= (ηι-η4) / η4) with respect to the first core of the cladding is 0.58%, and the relative refractive index difference Δη2 (= (η2-η4) with respect to the second core of the cladding ) / η4) is _018% in common, and the relative refractive index difference Aη3 (= (η3_η4) / η4) with respect to the third core of the cladding is 0.27〇 / 〇. These inventors measured various characteristics of the dispersion-leveling optical fiber at a wavelength of 1550 nm ', and the dispersion-leveling optical fiber is related to the embodiment i constructed as above. As a result, the dispersion at a wavelength of 1550 nm is -0.37 ps / nm / km (&lt; | 5 I ps / nm / km), and the effective cross-sectional area Aeff at a wavelength of 1550 nm is 52.8 &quot; 1112 (&gt; 45 &quot; 1112). The cut-off wavelength at a length of 2 meters is 1.713 &quot; 111 (&gt; 1.0 &quot; m). The dispersion slope is 0.0005 ps / nm / km at a wavelength of 1530 nm, 0.0005 ps / nm2 / km at a wavelength of 1550 nm (&lt; 0.003 ps / nm2 / km), and 0.0010 ps / nm2 / at a wavelength of 1560 nm. km. f The transmission loss (bending loss) at a diameter of 20 mm is 3 2 dB / m. Furthermore, the polarization dispersion at a wavelength of 1550 nm is 0.08 ps / km1 / 2 (&lt; 0.15 ps / km1 / 2). Fig. 8 is a graph showing the dispersion characteristics of the dispersion-leveling optical fiber according to the fourth embodiment. Fig. 9 is a table showing various characteristics of wavelengths of 1550 nm of respective dispersion-flattened optical fibers related to the above-mentioned embodiments 1 to 4. For any of the dispersion-leveling optical fibers related to the various embodiments, the absolute dispersion of the dispersion is in the range of 5 _-23- This paper standard is in accordance with the Chinese National Standard (CNS) A4 specification (21〇χ297297). ------ Crack--Ί. (谙 Read the notes on the back • Item ^ ί write this page) Order — d • · 401519 kl B7 V. Description of the invention (21) ps / nm / km or less, effective The area Aeff is above 45 # m2, the dispersion slope is below 0.03 ps / nm2 / km, the cut-off wavelength at a length of 2 meters is above 1.0 m, and the polarization dispersion is 0.15 ps / km1 / 2 or less. Printed by Huang Gong Consumer Cooperative, Central Standards Bureau, Ministry of Economic Affairs ------------- (please read the note on the back first to write this page) Any dispersion leveling optical fiber is also It has a very small dispersion slope and flat dispersion characteristics, and because the effective cross-sectional area Aeff is above 45 // m2 and is very large, it is necessary to suppress the power density of the light wave signal in the dispersion leveling fiber to a low power density. Effectively suppress the occurrence of non-linear optical phenomena, and make transmission with high S / N ratio possible. Moreover, because the cut-off wavelength is 2 meters in length Above 1.0, these dispersion leveling fibers have good bending characteristics (bending loss is small). Therefore, these dispersion leveling fibers are suitable for time-multiplexed multiplexing and wavelength multiplexing using optical amplifiers. Soliton transmission. In particular, the dispersion-leveling optical fiber related to Example 2 (Fig. 3) 'Because the effective cross-sectional area Aeff is above 70 m2, and the power density of the light wave signal in the dispersion-leveling optical fiber is suppressed At a lower level (more inhibiting the occurrence of non-linear optical phenomena). The dispersion leveling fiber (Figures 5A and 5B) related to Example 3 has a cut-off wavelength of 2 meters in length that is longer than the wavelength of light wave 1. However, as will be described later, if the actual transmission distance of the light wave signal is considered to be hundreds of kilometers to thousands of kilometers. Because the high-order mode (mode) will be reduced without any obstacles. Moreover, the present invention is not It is limited to the above-mentioned embodiment, and various modifications are also possible. For example, the refractive index side view shown in Example 4 is used as an example to explain the dispersion leveling light related to the present invention. A side view of refractive index, also of various other embodiments. ^ Some inventors, as shown! Square as shown, ready to change the side of the heart

401519 A7 B7 Printed by Shelley Consumer Cooperative of Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the invention (22) Samples 1 ~ 5 'of volume are used as an example of dispersion leveling optical fiber with refractive index side view shown in Figure 在. These samples are the relationship between the outer diameter of the apricot core area (the third core outer diameter) c2 and the dispersion slope (ps / nm2 / km), and the relationship between the third core outer diameter C2 and the cut-off wavelength at a length of 2 meters. Specifically, the prepared samples 丨 ~ 5 can change the second core outer diameter ratio (b 2 / c 2) with respect to the outer diameter of the third core and the relative refraction with respect to the third core of the second cladding. Rate difference Aw. On the other hand, the prepared sample is in common with other parameters, that is, the first core outer diameter ratio (a2 / c2) with respect to the third core outer diameter is 0,25, which is relative to the third core outer diameter. The outer diameter ratio (d / c2) of the i-th cladding is 2.0, the relative refractive index difference Δηι! 0.6% relative to the first core of the second cladding, and the relative refractive index difference relative to the second core of the second cladding The relative refractive index difference Δη4 of Ah and the first cladding layer is -0.055% in common. Figures UA and UB 'in the sample' are graphs showing changes in the dispersion slope (ps / nm2 / km) with respect to the outer diameter of the core area (third core outer diameter c 2); Figures 12A and 12B, in Sample 1 ~ 5 are graphs showing changes in the cutoff wavelength (#m) with respect to the third core outer diameter C2. In addition, in these drawings iia to FIG. 12B are the diagrams of each: si is a sample], S2 is a diagram of sample 2 and S 3 is a diagram of sample 3 'S 4 is a diagram of sample 4 and s 5 is a sample Picture of 5. From these figures, it can be understood that 'if the relative refractive index difference Δ113 with respect to the third core of the second cladding is too low, or the second core outer diameter ratio (b2 / c2) with respect to the outer diameter of the third core is Too large is that the dispersion slope cannot be lower than 0.000 ps / nm2 / km. In addition, the cut-off wavelength at a length of 2 meters becomes shorter, and the bending loss increases. Therefore, in order to reduce the dispersion slope, make the cut-off wavelength at a length of 2 meters longer, and improve the bending loss, the phase of the third core is -25- This paper standard applies the Chinese National Standard (CNS) A4 regulations (21〇χ 297 male '~~~ --- J ^-! (Please read the notes on the back to write this page first), order-line 0 (5) Printed by the Consumer Standards Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs A7 B7 V. Description of the invention (23) It is necessary to set the refractive index difference Δ113 to be larger, and it is necessary to make the width of the third core thicker. In addition, it is also used in the core area (having the third core) having the three-layer core structure described above. The dispersion-leveling optical fibers according to the third embodiment and the fourth embodiment are the side volumes of the third core represented by the following formula (5), each of which is 13.8%. # M2, 8.7%. &Quot; m2 (refer to the figure 9). C / 2 Δη (r) rdr b / 2 'These inventors prepared samples 6 to 9 each having the refractive index side views shown in FIGS. 13A to 13c as the same as in Example 3 (FIG. 5 A and FIG. 5 B) application examples of dispersion shifted optical fibers, and the various characteristics of these samples 6 to 9 were measured at a wavelength of 1550 nm. The structure of the prepared samples 6 to 9 is the same as the cross-sectional structure shown in FIG. 5A, which has the following: a core area composed of a first core, a second core, and a third core; and a first package The cladding area formed by the second cladding layer and the second cladding layer. Sample 6 is a refractive index side view 520 shown in FIG. 13A, and the refractive index side view 520 is equal to each area along the line L 2 in FIG. 5A. In the refractive index side view 520, the area 521 is equal to each part on the line L 2 of the first core 601, the area 522 is equal to each part on the line L 2 of the second core 602, and the area 523 is It is equal to each part on the line L 2 of the third core 603. The area 524 is equal to each part on the line L 2 of the first cladding 701. The area 525 is equal to each part on the line L 2 of the second cladding 702. In sample 6, the outer diameter a2 of the first core (refractive index ⑴) equal to field 521 is -26- This paper size applies the Chinese National Standard (CNS) A4 specification (210X297 公 #)

401519 A7 _______B7 V. Description of the invention (24) — 5_7 &quot; m, which is equal to the second core in the field 522 (refractive index n2 &lt; n〇 outer diameter ^ is I4.7 &quot; m 'equal to the third core in the field 523 (refractive index n3 &gt;; Il2) The center of the outer diameter is 22.6 &quot; m, which is equal to the first in the field 524! Cladding (refractive index n4 = n2) The outer diameter d is 45.2 // m, which is equal to the second cladding in the field 525 (refractive index n5> n4) ) The outer diameter is 125 m. Moreover, the relative refractive index difference (-(1 ^ -115) ½5) with respect to the first core of the second cladding layer is 0.6%. The relative refractive index difference Δη2 (= (n2-n5) / n5) of the second core and the relative refractive index difference Δη4 (= (η4-η5) / η5) of the first cladding layer are -0.05%, which is relatively The relative refractive index difference Ah (Ga !! 3-!! 5) / !! 5) of the third core of the 2 cladding is 〇30〇 / ^ or even the first core outer diameter with respect to the third core outer diameter The ratio (a2 / c2) is 025, and the second core outer diameter ratio (b2 / c2) to the third core outer diameter is 0.65. Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs ------------ Ί. (Please read the note on the back to write this page j Secondly, 'Sample 7 has the refractive index shown in Figure 13B Side view 53. The refractive index side view 530 is the refractive index of each area along the line L 2 in FIG. 5A. Also in this refractive index side view 53, the area 531 is equal to the first core 601. For each part on the line L 2, the area 532 is equal to each part on the line L 2 of the second core 602, and the area 533 is equal to each part on the line L 2 of the third core 603. The area 534 is equal to the first part. Each part on the line L2, the area 535 is equal to each part on the line L2 of the second cladding 702. Also, the prepared sample 7, the refractive index side view of the area 533 (equal to the third core area) The shape of the refractive index side view in the diameter direction is different from the shape of the area 513 in the refractive index side view 510 shown in FIG. 5B. In Sample 7, the outer diameter a 2 of the first core (refractive index η) equal to the area 53 1 is 5.6ym, which is equal to the outer diameter of the second core (refractive index η2 &lt; η) in the field 532. -27 -27 (CNS) from the secret (2 丨 Qx 297U ^ ~ j '~ 401519 A7 -------------- B7 V. Description of the invention (25) ~-~, which is equal to the first in field 533 3 cores (refractive index 叱> ^) outer diameter c2 is 24.2 &quot; m, which is equal to the i-th cladding of the field 534 (refractive index n4 = n2) outer diameter d is 48.4 &quot; m, which is equal to the second cladding of the field 535 (Refractive index ~,. The outer diameter is 125 &quot; m. Also, the relative refractive index difference (-(1 ^ -1 ^) / 115) with respect to the i-th core of the second cladding is 0.60%, relative The relative refractive index difference Ah (b%) of the second core of the second cladding layer and the relative refractive index difference (= (n4-n5) / n5) of the i-th cladding layer are collectively 0. 05%, and The relative refractive index difference Δ113 (= (η3 · η5) / η5) with respect to the third core of the second cladding is 0.41%. Furthermore, the ratio of the i-th core outer diameter to the outer diameter of the third core ( a2 / c2) is 〇23, and the second core outer diameter ratio (b2 / c2) with respect to the third core outer diameter is 〇52. The Central Consumers Bureau of the Ministry of Economic Affairs, the Consumer Cooperatives of India, sample 8 is shown in Figure 13C. The refractive index side view 54o, the refractive index side view 540 is the refractive index of each area equal to the line l2 in FIG. 5a. In the refractive index side view 540, the area 541 is equal to each part on the line L2 of the first core 601, the area 542 is equal to each part on the line L2 of the second core 602, and the area 5 43 is equal to the third core 603. The respective regions' field 544 on the line L 2 are equal to the respective regions on the line 12 of the first cladding 701. The regions 545 are equal to the respective parts on the line L 2 of the second cladding 702. The shape of the refractive index side view of the prepared sample 8 'field 541 (equivalent to the refractive index side view in the diameter direction of the first core field) is different from the shape of the field 511 of the refractive index side view 510 shown in FIG. 5B. In sample 8 ', the outer diameter a2 of the first core (refractive index η) of the domain 541 is 8.6 &quot; m, and the outer diameter b2 of the second core (refractive index η2 &lt; η) of the domain 542 is 17_6 # m, which is equal to the domain 543 The third core (refractive index! ^〉! ^) Outer diameter c2 is 25.2 ym, which is equal to the first cladding of the field 544 (refractive index n4 = n2) and the outer diameter d is -28- This paper uses Chinese national standards ( CNS) A4 specification (210X297 ^ 1 ~~~~ '401519 A7 B7 V. Invention Description (26 printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs, printed by 50.4 &quot; m, which is equivalent to the second cladding of area 545 (refraction The outer diameter is 125 &quot; m. The relative refractive index difference ΔI (= (ηι_η5) / η5) with respect to the i-th core of the second cladding is 0.85%, relative to the second package. The relative refractive index difference Δη2 (^ nm5) / !! 5) of the second core of the layer and the relative refractive index difference △ of the cladding layer are (Kn4-!! 5) / !! 5), which are _0.05%, The relative refractive index difference (= (η3_η5) / η5) with respect to the third core 4 of the second cladding is 〇29%. Furthermore, the i-th core outer diameter ratio (a2 / c2) is 34, and the outer diameter of the second core relative to the outer diameter of the third core (B2 / c2) is 〇74. On the other hand, sample 9 is a side view with a refractive index similar to the above-mentioned sample 6 (refer to FIG. 13A). Therefore, in sample 9, it is equal to the second core of the field 5Z1 The outer diameter a2 is 6.6; um is equal to the second core (refractive index η2 &lt; η) of the domain 522 and the outer diameter 152 is 18.9 # 111, which is equal to the third core (refractive index ηθη2) of the domain 523 and the outer diameter c2 is 25.2; um, The outer diameter d of the first cladding (refractive index neri2) equal to the domain 524 is 41.0 and m, and the outer diameter of the second cladding (refractive index θη4) equal to the domain 525 is 125 / im. Also, compared to the second envelope The relative refractive index difference of the first core to the layer is 0.05%, and the relative refractive index difference Δη2 (= (η2 · η5) / η5) to the second core of the second cladding layer and the relative refractive index of the first layer The rate difference Δ114 is _〇 丨 5% in common, and the relative refractive index difference Δη3 (= (n3_n5) / ㈧) which is coincident with the third core of the second cladding is 0.43%. Moreover, compared to the outer diameter of the third core The outer diameter of the i-th core (a2 / c2) is 0-26, and the outer diameter of the second core relative to the outer diameter of the third core ... (b2 / c2) is 0.74 ^ With the above structure, a positive dispersion is obtained値 with extremely small color Slope dispersion leveling fiber. Figure 14 shows the samples of the 6 to 9 wavelengths of 1550nm as designed above. Please read the 'Items on the back side of the book' for comparison. -29- This paper standard applies to Chinese national standards. (CNS) A4 ^ i ~ 7 ^ x297 / Avi &quot; 401519 Α7 Β7 V. Description of invention (27) Various characteristics are printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs. 〇% · &quot; m2 or more. Considering the side volume of the third core represented by the formula (5), considering each of the above-mentioned samples 3-9. Furthermore, these inventors measured the relationship between the side-dispersion leveling optical fiber (Sample 7) having the refractive index shown in FIG. 13B and the third core. C2 (outer diameter of the core area) and various characteristics described above. 3 samples prepared. Moreover, the relative refractive index difference Δη! Of the prepared sample with respect to the first core of the second cladding is 0.61% 'relative to the second core of the second cladding The relative refractive index difference Δη; ί (= (n2_n5) / n5) and the relative refractive index difference Δ114 (= (η4 · η5) / η5) of the i-th cladding layer are -0.05%, and relative to the The relative refractive index difference (= (η3_η5) / η5) of the third core of the 2 cladding is 0%. The second cladding is made of pure silicon. Furthermore, the first core outer diameter ratio (a2 / c2) with respect to the third core outer diameter is 0.23, and the second core outer diameter ratio (b2 / c2) with respect to the third core outer diameter is 0.52, and The first cladding outer diameter ratio (d / c2) to the third core outer diameter was 1.8. 15A to 15D are the measurement results of the prepared sample, and FIG. 5A is a diagram illustrating the outer diameter c2 (#m) of the third core and the effective cross-sectional area of the third core. Fig. 15C shows the relationship between the outer diameter c2 (&quot; m) of the third core and the dispersion slope (ps / nm2 / km), and Fig. 15D shows the third core. Relationship between outer diameter c2 (&quot; m) and dispersion (ps / nm / km). In each figure, the curves L3, L4, L5, and L6 are theoretical curves obtained by calculation, and the dots (dot) drawn represent the measurement 値. It is understood from these graphs that the obtained dispersion leveling fiber has a dispersion chirp (&lt; 丨 5 | ps / flm / k ------ at wavelength · rnn) of -4 to +4 ps / nm / km. --- Installation-C Please read the back first. -C Note that Dong Xiang's manuscript is ordered 1¼ 〇 • m 30- This paper size is applicable to China National Standards (CNS) Λ4 Regulations (2 丨 〇297297 漦 401519 Central Ministry of Economic Affairs Standard Bureau employee consumer cooperatives printed A7 B7 ^ ·, invention description (28) 0.026 ~ 0.028 ps / nm2 / km dispersion slope (&lt; 0 03 ps / nm2 / km), 47 ~ 52 m2 effective cross-sectional area Aeff ( &gt; 45 # m 2). In particular, the point that must be noticed in FIG. 15C is the area shown by a in the figure, which is the point where changing the outer diameter of the third core also makes the dispersion slope change smaller. Generally, When manufacturing optical fibers, between the manufactured groups, the outer diameter of the core area will produce a process error of about ± 2% (only to the extent of ± 20/0 and can only be controlled by the outer diameter). Therefore, if the The error range of dispersion slope If you want to control the outer diameter of the core area, you must be able to avoid the characteristic error of various manufactured objects (dispersion leveling fiber) caused by manufacturing errors. Fig. 16A and Fig. 16B are sample 8 showing the relationship between the change in outer diameter of the core area and changes in various characteristics, and Fig. 16A shows the third core outer diameter c 2 and dispersion (ps / nm) / km) and the dispersion slope (ps / nm2 / km), FIG. 16b is a graph showing the variation of the dispersion slope (ps / nm2 / km / 0 / 〇) relative to the change rate (%) of the outer diameter of the core area. In Fig. 6a, D is the dispersion of the sample 8 and DS is the dispersion slope of the sample 8. It is also understood from Fig. 16A that according to the diameter change in the field of propagating light signals (mainly the core area) When it is large, the dispersion chirp also becomes large, and the dispersion slope has a very small chirp when it has the third core outer diameter c 2 値. In particular, the variation of the dispersion slope becomes smaller near the minimum chirp. Specifically, It can also be understood from the graph shown in Figure 丨 6B that if the core area outer diameter is set to be appropriate to design a dispersion leveling fiber, relative to the core area outer diameter variation rate that can control ± 2% of the outer diameter, It is possible to suppress the variation of dispersion slope to less than 0.003 ps / nm2 / km /%. Secondly, it is related to the present invention. Dispersion leveling optical fiber is about bending loss -31-Applicable to Zhongguanjia County (CNS) Α4 specification (21GX297 male ϋ --------- install I (Please read the back 4 first to avoid the items! ^ Write (This page)

1T 401519 A7 B7 V. Description of the invention Bismuth) loss (dB / m) and cut-off wavelength. FIG. 17A is a measurement chart showing the bending loss (dB / m) of fixing the third core outer shell C2 at 22.4 jum and plotting the plot relative to the change in the radius of curvature (mm), and L7 in the figure is obtained by Calculated theoretically. It can also be understood from this figure that the bending loss at a curved diameter of 32 mm is 0.04 dB / m (= 0.004 dB / turn), and it can be understood that it is a good value. On the other hand, FIG. 17B is a measurement chart showing that the outer diameter C2 of the third core is fixed at 22.8 &quot; m, and the cutoff wavelength (&quot; m) is plotted against the change in the fiber length (km). L8 in the figure is The theory obtained by calculation. In addition, the slope of line 18 is -252 nm / decade (nano / decimal). It can also be understood from this figure that the cut-off wavelength at a length of 2 meters is 2.080 # m. If it is a length of about 200 meters, 'in order to ensure single mode operation, the cut-off wavelength ratio at a length of 2 meters There is also no practical problem when the wavelength of the light wave 彳 &amp; is long (usually, in the submarine cable, etc., multiple 5 km optical fibers are fused to form an optical transmission path). Central Government Bureau of Standards, Ministry of Economic Affairs, Consumers' Cooperatives, Printing I -------- Installation --Γ-(Please read the precautions on the back to write this page)

Furthermore, FIG. 18A shows the relationship between the lateral volume (%. &Quot; m2) of the third core and the dispersion slope (ps / nm2 / km) in the above-mentioned samples i ~ 5 ′. Samples 丨 ~ 5 show the relationship between the side volume of the third core (% &quot; edge and cut-off wavelength (ym). As mentioned above, dispersion-leveling optical fibers in core areas with three-layer cores and structures (with In the third core of Example Q and Example 4), the cutoff wavelength at a length of 2 meters must be 14 and the dispersion slope is preferably less than 0.03 ps / nm3 / km. Therefore, to meet these restrictions From Fig. 18A and Fig. 18B, relative to the valley product (refer to the formula (5)) must be at 7.0%. &Quot; m2 flushed. Also 'in Figure-32- This paper size applies the Chinese National Standard (CNS ) Λ4 Regulations (210X297 Department's) 5. Description of the invention (30A7 B7 Printed by UA and Central Laboratories of the Central Bureau of Standards and Engineering Co., Ltd. UA and Figure 18B, si ~ S5 are the samples 1 ~ 5 shown above, And the dispersion slope and cutoff wavelength relative to the side volume. The availability on product A is above according to the detailed description, and The dispersion-leveling optical fiber related to the invention 'the absolute dispersion at a wavelength of 1550 nm is below 5 ps / nm / km and' because the dispersion slope is below 0.03 ps / nm2 / km, the difference in dispersion between the various light wave signals is Use the front end of the wavelength band and suppress it in the small fan garden. Also, the effective cross-sectional area is preferably above 45 &quot; m 2. By realizing the appropriate relationship between these effective cross-sectional areas and dispersion slopes, it is possible to level the dispersion. The power density of the optical wave signal in the optical fiber is suppressed at a low power density to effectively suppress the occurrence of non-linear optical phenomena, making transmission with a high S / N ratio possible, or even because the cut-off wavelength at a length of 2 meters is at 10%. &quot; mg, the dispersion leveling fiber has good bending characteristics. Therefore, the dispersion leveling fiber is suitable for time division multiplexing and wavelength multiplexing soliton transmission using optical amplifiers. Also, the effective cross-sectional area When it is above 70 &quot; m2, the power density of the light wave signal in the dispersion leveling fiber is further suppressed to a low power density, and the occurrence of nonlinear optical phenomena can be more effectively suppressed. The leveling fiber is &amp; further-suitable for time division multiplexed transmission and wavelength multiplexed soliton transmission using optical amplifiers.-乂 (Please read the note on the back first to write the spirit) _ -33- This paper size Applicable to the Chinese National Standard (CNS) Λ4 specification (210X 297 ^ 7 Revised Chinese Manual of the Di Li application (February 89) V. Description of the invention-(View)

Printed by the Consumer Standards Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs. Cladding area 301 First cladding 302 Second cladding 510 Index side view 511,512,513,514,515 Field 520 Index side view 521,522,523,524,525 Field 530 Index side view 53 1,532,533,534,535 Field 540 Index side view 541,542,543,544,545 Field 600 Core field 601 First core field 602 The second core area 603 The third core area 700 The cladding area 701 The first cladding 702 The second cladding-33a- nn I 1 ^ 1 n II-^^-^ II Ding Yi 0¾ i Read · (Please read first Note on the back, please fill out this page again) This paper size is applicable to China National Standard (CNS) A4 specification (210X297 mm)

Claims (1)

401519 Α8 Β8 C8 D8 Printed by the Central Laboratories of the Ministry of Economic Affairs, Shelley Consumer Cooperatives 6. Scope of patent application 1. A dispersion leveling optical fiber, characterized in that the dispersion leveling optical fiber is provided with: a core area extending along a predetermined axis ; And the cladding area located on the outer periphery of the core area; and has the following characteristics as the wavelength of 1550 nm: Absolute chirp is dispersion below 5 ps / nm / km; effective cross-sectional area above 45 # m2; A dispersion slope below 0.03 ps / nm2 / km; a cut-off wavelength of 1.0 &quot; m or more at a length of 2 meters. 2. For the dispersion-leveling optical fiber in the first scope of the patent application, the effective cross-sectional area is below 50 a m2, and the dispersion slope is below 0.02 ps / nm2 / km. 3. For the dispersion-leveling optical fiber in the first scope of the patent application, the above-mentioned core area is provided with: a first core having a predetermined refractive index; and a second core located outside the periphery of the first core, And has a higher refractive index than the first core. 4. For the dispersion-leveling optical fiber in the first scope of the patent application, the above-mentioned core areas are equipped with the following: the first core has a predetermined refractive index; the second core is located on the periphery of the first core. And has a lower refractive index than the first core; and a third core is provided on the outer periphery of the second core and has a higher refractive index than the second core. 5. The dispersion-leveling optical fiber according to any one of claims 1 to 4, wherein various characteristics as the above-mentioned wavelength of 1550 nm further have a polarization wave dispersion of 0.15 ps / km1 / 2 or less. 6. If the dispersion leveling optical fiber in any of the items 1 to 4 of the scope of the patent application, -34-In-use paper ® ® Home ladder standard (CNS) A4 specification (210X297 mm) &quot; (Please First read the precautions on the back and then fill out this page) Pack-A8 B8 C8 D8 Printed by the Central Laboratories of the Ministry of Economic Affairs, Shelley Consumer Cooperatives 6. The scope of application for patents, where the transmission loss when bent into a straight 32 mm is 〇. Below 5 dB / turn, the cut-off wavelength at the above 2 meters length is above i4 &quot; m. 7. For the dispersion-leveling optical fiber in the scope of the patent application, the following relationships are satisfied: The outer diameter of the second core is b, and the outer diameter of the third core is c. When the relative refractive index difference of the third core is Δη3, Δη3 ^ 0.25% 0.40Sb / c ^ 0.75 8. For example, the dispersion leveling optical fiber of the seventh scope of the patent application, which satisfies the following relationships: The distance in the radial direction is r. When the relative refractive index difference with respect to the reference area of the above-mentioned cladding area is An (r) at a distance r from the center, c / 2! Δπ (r) rdr ^ T. 0 (% · / ^ Πι2) b / 2 9_If the dispersion leveling optical fiber of item 7 of the scope of patent application, which meets the following relationships: The above cladding field is equipped with: the first cladding, which is located in the third The outer periphery of the core has a lower refractive index than the third core; and the second cladding layer is an area equal to the above referenced area, and is provided on the outer periphery of the first cladding layer and has a higher thickness than the first cladding layer. Higher refractive index, the outer diameter of the first core is a, the outer diameter of the second core is b, and 35 This paper size is applicable to China National Standards (CNS) A4 (2 丨 0X297 mm) π Please read the note f on the back before filling in this page] Loading ·-, 1T- ABCD Industrial and Consumer Cooperatives Co., Ltd. 401519 ~, patent application scope-the outer diameter of the third core is c, which is Δηι '* relative to the above, and the core difference between the first and second cores is Δηι' *. When the relative refractive index difference of the second layer of the second cladding layer is Aη4, C 0.40% ^ Δηι ^ 0.90% Δη4 ^ -0.02 ° / 〇0.20 each a / c 0.35 20 / ^ m ^ c ^ 3〇A &lt; ni 10_If you apply for a patent Fan Yuandi! The dispersion-leveling optical fiber of the above item, wherein the outer diameter of the core area is set to within a range of ± 2% when the dispersion slope is extremely small (where 値 is medium =). 11. For the dispersion-leveling optical fiber of item i of the patent application park, the variation of the dispersion slope above ± 2% of the outer diameter of the core area is below 0_003 ps / nm2 / km. 12. A dispersion leveling optical fiber, which is characterized by having: a core area extending along a predetermined axis; and a cladding area provided on the outer periphery of the core area, which have various characteristics as the wavelength of 1550 nm: Effective cross-sectional area above 45 Aim2; and dispersion slope below 0.03 ps / nm2 / km; and the above core area is equipped with: the first core, which has a predetermined refractive index, and is relative to the reference area of the above cladding area The relative refractive index difference is less than 0.6%; the second core is provided on the outer periphery of the first core and has a lower refractive index than the first core; and the third core is provided on the first core The outer periphery has a higher refractive index than the second core. -36 This paper xjt is suitable for Zhongguan Family Materials (CNS) Eighty Four Secrets (21GX297 Mody Thin) A8 B8 C8 D8 VI. Patent Application Fan Garden 13. If the dispersion leveling optical fiber of item 丨 2 of the patent application scope, the above effective cross-sectional area is above 50 // m2, and the above dispersion slope is 〇02 ps / nm2 / km below, as the various characteristics of the above-mentioned wavelength of 1550 nm, and further has: absolute chirp is a dispersion below 5 ps / nm / km. 14. If the scope of patent application is the first! The two-level dispersion leveling fiber further has polarization wave dispersion of 0.15 ps / km1 / 2 or less as various characteristics of the above-mentioned wavelength of 1550 nm. 15. The dispersion-leveling optical fiber according to item 12 of the patent application, wherein the transmission loss when bent to a diameter of 32 mm is below 0.5 dB / turn. I6. If the dispersion leveling optical fiber of item 12 of the patent application scope meets the following relationships: The outer diameter of the second core is b, the outer diameter of the third core is c, and it is relative to the reference area of the cladding field. When the relative refractive index difference of the third core is Δη3, Δη3 ^ 0.25% 0.40Sb / cS0.75 17 · As for the dispersion leveling optical fiber of the 16th scope of the patent application, among them the following are relevant: Central of the Ministry of Economic Affairs Printed by the Standard Bureau Shellfish Consumer Cooperative (please read the precautions on the back before filling out this page) The distance from the center of the core area in the radial direction is r, at the distance r from the center, and relative to the cladding When the relative refractive index difference of the reference field in the field is Δη (Γ), c / 2 S 厶 n (r) rdr27. 〇b / 2 -37- This paper China National Standards (CNS) eighty-four secret (_21〇x297 (Mm) Α8, B8, C8, D8 6. Scope of patent application 8. If the dispersion-leveling optical fiber of item 12 of the patent application scope meets the following relationships: 1. The cladding field is provided: The first cladding is In the third nucleus, (the outer periphery ', 3 cores have a lower refractive index; and the second cladding layer is an area equal to the above reference field, and is provided on the outer periphery of the cladding layer &lt; and has a higher refractive index than the first cladding layer; The outer diameter of the first core is a, the outer diameter of the second core is b, and the outer diameter of the third core is c. The comparative refractive index difference with respect to the first core of the second cladding is Δηι, and 2 When the relative refractive index difference of the above-mentioned upper cladding layer is Δη4, Δη4 ^ -0.02% 0.20 ^ a / c ^ 0.35 20 am S c S 3 0 # m 19. Dispersion leveling optical fiber, in which the outer diameter of the core area is set within a range of ± 2% around the above-mentioned dispersion slope when the dispersion slope is extremely small. 20. If the scope of patent application is No. 2 for dispersion calibration For flat optical fiber, the variation of the dispersion slope above ± 2% of the outer diameter of the core area is below 0.003 ps / nm2 / km. (Please read the precautions on the back before filling in this page; &gt; oi Equipment-Printed by the Consumers' Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs-38- Bu scale with Chinese National Standard (CNS) A4 size (210X297 mm)