CN107728403B - Wavelength converter with wavelength ranging from 1.55 mu m to 2 mu m - Google Patents
Wavelength converter with wavelength ranging from 1.55 mu m to 2 mu m Download PDFInfo
- Publication number
- CN107728403B CN107728403B CN201711013472.0A CN201711013472A CN107728403B CN 107728403 B CN107728403 B CN 107728403B CN 201711013472 A CN201711013472 A CN 201711013472A CN 107728403 B CN107728403 B CN 107728403B
- Authority
- CN
- China
- Prior art keywords
- air holes
- input
- wavelength
- photonic crystal
- division multiplexer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02295—Microstructured optical fibre
- G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
- G02B6/02342—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by cladding features, i.e. light confining region
- G02B6/02347—Longitudinal structures arranged to form a regular periodic lattice, e.g. triangular, square, honeycomb unit cell repeated throughout cladding
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/355—Non-linear optics characterised by the materials used
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/365—Non-linear optics in an optical waveguide structure
Abstract
A wavelength converter of 1.55 μm band to 2 μm band, comprising a first wavelength division multiplexer having an input port for inputting pulse light of 1.55 μm band inputted to the wavelength converter, a tellurate photonic crystal fiber for realizing group velocity matching, a second wavelength division multiplexer having an output port for outputting pulse light of 1.55 μm band, and a coupler having an input port for inputting continuous light of 2 μm band, an output port for outputting pulse light of 1.55 μm band as an output of the wavelength converter, the tellurate photonic crystal fiber being connected between the first input output port and the third input output port, the second input output port being connected to a fifth input output port, the fourth input output port being connected to a sixth input output port. In the cross phase modulation, the group velocity matching and the high nonlinearity of the wavelength converter overcome the walk-off effect between two wavelengths, and ensure the high efficiency of the cross phase modulation.
Description
Technical Field
The present invention relates to the field of optical fibers, and more particularly to wavelength converters of the 1.55 μm to 2 μm wavelength band.
Background
With the development of communication technology and the strong demand of people for information interaction, all-optical communication network technology is indispensible to become the main force of global communication. The rapid development of optical communication networks has led to an exponential increase in their capacity over the last few decades, with many technological breakthroughs including low-loss single-mode transmission fibers, erbium-doped fiber amplifiers, wavelength division multiplexing, etc. For long-range and large-capacity transmission, most of the work has been done in the C-band communication window (1530 nm to 1565 nm), where fiber transmission loss is minimal, and low noise amplification can be obtained, advanced modulation format signaling allows for an efficient increase in capacity within this limited bandwidth. However, the bandwidth distance product of the capacity transmission is ultimately limited by fiber nonlinearities. As internet traffic grows exponentially, today's telecommunication networks are rapidly pushing towards their capacity limits, raising concerns about potential future "capacity tightening". The existing 1.55 μm band (1530-1565 nm) optical fiber communication system has approached the limit of transmission capacity, and one of the effective means to solve this problem is to open up a new optical transmission band. With the rapid development of 2 μm band related technologies and the huge gain bandwidth (1.8 μm-2.1 μm) provided by Thulium Doped Fiber Amplifiers (TDFAs), the 2 μm band has had great potential to become the next fiber transmission window. The 2um wave band (1.8-2.3 um) light has high molecular absorption peaks to carbon dioxide, water and the like, belongs to the human eye safety wave band, and has wide application in various fields, such as laser radar, laser scalpel, material processing shaping, optical fiber sensor and the like, which are safe to human eyes.
Tellurate glass has the advantages of high refractive index, high nonlinear refractive index, high rare earth doping concentration, high expansion coefficient, low phonon energy, low melting point, good stability, corrosion resistance, special magneto-optical property and the like, and is actively applied to lasers, nonlinear devices and the like.
In the wavelength division multiplexing system of the all-optical network, the wavelength conversion technology is one of the key technologies, and is also one of the effective means for solving the capacity limitation of the optical transmission band, and the wavelength conversion is to transfer the information carried by one wavelength onto the other wavelength for transmission. While wavelength conversion techniques based on cross-phase modulation can be used for intensity modulation to create mode locking. In the prior art, wavelength conversion based on cross phase modulation is realized by adopting a dispersion shift optical fiber, however, the existing dispersion flat shift optical fiber mainly realizes near-zero dispersion flatness in a wave band of 1.55 mu m, and values are taken according to intervals in the wave band of 1.55 mu m, so that the available wavelength number is very limited; in cross-phase modulation, the prior art has not been able to extend the 1.55 μm band to the 2 μm band with dispersion shifted fibers due to walk-off effects.
Disclosure of Invention
The invention aims to solve the technical problems of insufficient cross phase modulation and interference of walk-off effect in large-span wavelength conversion based on cross phase modulation and provides a wavelength converter from 1.55 mu m wave band to 2 mu m wave band, which aims to solve the technical problems of controllable cross wave band group velocity matching wavelength of 1.55 mu m wave band and 2 mu m wave band in the prior art.
The invention provides a wavelength converter with a wave band of 1.55 mu m to 2 mu m for solving the technical problem, which comprises a first wavelength division multiplexer, tellurate photonic crystal fiber for realizing group velocity matching, a second wavelength division multiplexer and a coupler; the first wavelength division multiplexer is provided with a first input and output end, a second input and output end and an input port used for being connected with pulse light of a 1.55 mu m wave band input to the wavelength converter, the second wavelength division multiplexer is provided with a third input and output port, a fourth input and output port and an output port used for outputting pulse light of the 1.55 mu m wave band, the coupler is provided with an input port used for being connected with continuous light of the 2 mu m wave band, an output port used for outputting pulse light of the 1.55 mu m wave band as the output of the wavelength converter, a fifth input and output end and a sixth input and output end, the tellurate photonic crystal fiber is connected between the first input and output end and the third input and output port, the second input and output end is connected with the fifth input and output end, and the fourth input and output port is connected with the sixth input and output end.
In the wavelength converter of the present invention, the structure and connection of the various parts of the wavelength converter are further defined by the flow direction of the following signals:
the signal flow direction of the pump light pulse with the wave band of 1.55 mu m is as follows: the first wavelength division multiplexer, tellurate photonic crystal fiber, the second wavelength division multiplexer and then flows out;
the flow direction of light of 2 μm wave band entering the coupler is divided into two paths, one path is in sequence: the coupler, the first wavelength division multiplexer, the tellurate photonic crystal fiber and the second wavelength division multiplexer are connected in sequence, and then flow back to the coupler, and the other path is as follows: the device comprises a coupler, a second wavelength division multiplexer, a tellurate photonic crystal fiber, a first wavelength division multiplexer and a back flow to the coupler.
In the wavelength converter of the invention, the tellurate photonic crystal fiber is provided with a fiber core and a cladding which are made of a base material 60TeO2-20PbO-20PbCl2, wherein the base material is internally provided with a plurality of air holes which are arranged in parallel along the axis of the tellurate photonic crystal fiber; on any cross section of the tellurate photonic crystal fiber: the air holes are distributed in multiple layers along the axis of the tellurate photonic crystal fiber, the air holes of each layer are arranged into regular hexagons, the distance between the hole centers of any two adjacent air holes is P=4μm+/-0.25 μm, the diameter d1 of each air hole of the innermost layer is 3.0-3.7 μm, the diameter difference of any air hole of the innermost layer is within 0.5 μm, the diameter d of the rest of air holes is 3 μm+/-0.5 μm, or the distance P between the hole centers of any two adjacent air holes is 3.80-4.15 μm, the distance between the hole centers of any two adjacent air holes is within 0.725 μm, the diameter d1 of the air hole of the innermost layer is 3.3 μm+/-1.45 μm, and the diameter d of the rest of air holes is 3 μm+/-1.45 μm; the core is formed by the base material surrounded by circles formed between the centers of the innermost air holes, and the cladding is formed by the other base material and all air holes.
In the wavelength converter of the present invention, in each regular hexagon, an air hole is provided at the intersection point between any adjacent two sides.
In the wavelength converter of the present invention, the distance between the centers of any two adjacent air holes is p=4 μm, the diameters d1 of the air holes of the innermost layer are equal, the d1 range is 3.0 to 3.7 μm, the diameters d of the remaining air holes are 3 μm, or the distances between the centers of any two adjacent air holes are equal, P is 3.80 to 4.15 μm, the diameters d1 of the air holes of the innermost layer are 3.3 μm, and the diameters d of the remaining air holes are 3 μm.
In the wavelength converter of the present invention, the diameter of the air hole of the innermost layer and the distance between the centers of any two adjacent air holes are further defined by the ratio K of the diameter of the air hole of the innermost layer to the distance between the centers of any two adjacent air holes, the range of K being 72% to 92%.
At the wavelength of the present inventionIn the converter, for any one of the tellurate photonic crystal fibers, the size of the fiber core diameter is 2P min ～2P max Within, P min P max Respectively represent the minimum value and the maximum value of the distance between the hole centers of two adjacent air holes of the tellurate photonic crystal fiber.
In the wavelength converter of the present invention, the light of the 2 μm wavelength band is specifically light of the 2.025 μm wavelength.
In the wavelength converter of the present invention, the first wavelength division multiplexer, the tellurate photonic crystal fiber, the second wavelength division multiplexer and the coupler are connected into a ring, and the length of the optical fiber contained in the ring accords with the following formula:
π＝2Pγ 12 L
wherein P is input signal power, L is optical fiber length, and gamma 12 Is a nonlinear coefficient associated with cross-phase modulation.
In the wavelength converter of the present invention, the coupler is a 3dB coupler.
The implementation of the invention has the following beneficial effects: in the cross phase modulation, the wavelength converter of the invention overcomes the walk-off effect between two wavelengths by group velocity matching and high nonlinearity, and ensures the high efficiency of the cross phase modulation; besides the innermost air holes, the air holes of each layer have the same diameter, are simply arranged and relatively simple to draw, the diameter and the hole spacing of the outer air holes can be properly adjusted according to the manufacturing process and the fusion process, the characteristics of the optical fiber are hardly affected, and the group velocity matching of any wavelength of 1.55 mu m and 2 mu m wave bands can be realized by adjusting the photonic crystal fiber structure.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is 60TeO 2 -20PbO-20PbCl 2 A plot of refractive index of tellurate glass as a function of wavelength;
FIG. 2 is a two-dimensional cross-sectional view of the basic structure of a tellurate photonic crystal fiber in a wavelength converter of the present invention;
fig. 3 (a) is a fundamental mode field diagram of the structure of fig. 2, p=4 μm, d=3 μm, d1=3.3 μm, and 1.55 μm for an effective refractive index of 2.0832;
fig. 3 (b) shows the fundamental mode field of 2.025 μm for the structure of fig. 2 with p=4 μm, d=3 μm, d1=3.3 μm and an effective refractive index of 2.069;
FIG. 4 is a schematic diagram of a group velocity-dependent wavelength curve and a group velocity matching process of tellurate photonic crystal fibers with different first layer air hole diameters d1 under the condition of P=4μ m d =3μm;
fig. 5 is a graph showing the effective refractive index of tellurate photonic crystal fibers with different first layer air hole diameters d1 according to wavelength under the condition of p=4μ m d =3μm;
fig. 6 is a graph of group velocity versus wavelength for p=4μ m d =3μ m d1 =3.3 μm tellurate photonic crystal fibers;
fig. 7 is a graph of dispersion versus wavelength for p=4μ m d =3μ m d1 =3.3 μm tellurate photonic crystal fiber;
fig. 8 is a graph of wavelength matching 1.55 μm group velocity as a function of first layer air hole diameter d1 with p=4μ m d =3μm;
fig. 9 is a graph of wavelength matching 1.55 μm group velocity as a function of hole pitch P with d=3μ m d 1=3.3 μm;
FIG. 10 is a graph of a cross-phase modulation based wavelength conversion model in a group velocity matching photonic crystal fiber based wavelength converter;
fig. 11 (a) is a waveform diagram of an input pulse of 1.55 μm at the input end at the time of wavelength conversion, and fig. 11 (b) is a waveform diagram of an output pulse of 2.025 μm at the output end at the time of wavelength conversion.
Detailed Description
For a clearer understanding of technical features, objects and effects of the present invention, a detailed description of embodiments of the present invention will be made with reference to the accompanying drawings.
The substrate material for tellurate photonic crystal fiber designed by the invention is 60TeO 2 -20PbO-20PbCl 2 (TLX) calculation using three Sellmeier equationsRefractive index thereof:
n 2 (λ)＝1+B 1 λ 2 /(λ 2 -C 1 )+B 2 λ 2 /(λ 2 -C 2 )+B 3 λ 2 /(λ 2 -C 3 )
where λ is the wavelength in μm, B i (i=1, 2, 3) and C i (i=1, 2, 3) is a coefficient, and six coefficients corresponding to TLX glass are respectively: b (B) 1 ＝1.212，B 2 ＝2.157，B 3 ＝0.1891，C 1 ＝6.068×10 -2 ，C 2 ＝7.068×10 -4 ，C 3 = 45.19. The refractive index of TLX is very high and its refractive index profile with wavelength is shown in fig. 1. Tellurate material 60TeO used in the present invention 2 -20PbO-20PbCl 2 (TLX), nonlinear index of refraction up to 5X 10 -19 m 2 And the dispersion, the nonlinear coefficient, the group velocity and the like of the photonic crystal fiber can be adjusted by adjusting the structural parameters of the photonic crystal fiber because the structure of the photonic crystal fiber is changeable, thereby achieving the fiber structure meeting the requirements.
A sectional view of a tellurate photonic crystal fiber designed by the invention is shown in fig. 2, and the fiber structure consists of a fiber core structure and a cladding structure. The photonic crystal fiber comprises a substrate material and air holes which are arranged on the substrate material and penetrate through the whole fiber length, six layers of air holes are arranged according to regular hexagons, the air holes are arranged in parallel along the axis of the tellurate photonic crystal fiber, the hole spacing P (the distance between the hole centers of the air holes) between every two adjacent air holes is equal, and the diameter of the air hole of the first layer is d 1 The remaining air holes had a diameter D, a cladding diameter d=57 μm, and a base material of 60TeO 2 -20PbO-20PbCl 2 (TLX). The fiber core structure is a substrate material TLX surrounded by a first layer of air holes in the substrate material, namely, the substrate material surrounded by circles formed among the hole centers of the innermost layer of air holes forms a fiber core, the diameter of the fiber core is 2P, the axis of the fiber core is the axis of the tellurate photonic crystal fiber, and other substrate materials and all air holes form a cladding.
We are derived from the original Sellmeier equation
It is known that for a certain material, different ω corresponds to different n (ω), so c/n (ω) is different, i.e. the light transmission speed in the waveguide is different. Light of different propagation speeds can appear to walk away during transmission, resulting in pulse broadening, which is very limiting for optical communications.
From a mathematical point of view, the dispersion effect of an optical fiber can be measured at the center frequency ω 0 The taylor series, which is developed as a modulus transfer constant β:
wherein, the liquid crystal display device comprises a liquid crystal display device,
so that it is possible to obtain:
wherein n is g Is a group refractive index, n is defined according to the ratio of the refractive index to the speed of light in two media g ＝c/v g ；v g For group velocity, obviously corresponding to the group refractive index, the propagation velocity of the envelope of the light pulse is described; beta 2 Is group velocity dispersion; beta 3 Is the third-order dispersion parameter (TOD).
Dispersion describes the difference in refractive index, mode and transmission speed of a beam of light due to the difference in wavelength in a waveguide, thusWhen reaching the receiving end, the phenomenon of pulse broadening is caused by the walk-off effect. In fiber optics, we typically replace group velocity dispersion β with the dispersion parameter D 2 ：
Wherein n is eff N in the original formula is replaced to represent the effective refractive index.
The chromatic dispersion controllability of the photonic crystal fiber is derived from the change of the refractive index distribution of the fiber cross section, and the structural change of the photonic crystal fiber is just the refractive index distribution of the fiber cross section. The tellurate photonic crystal fiber designed by the invention is a refractive index guided photonic crystal fiber, and light tends to propagate in a high refractive index region. The refractive index of the tellurate material is larger, the introduction of air holes in the cladding layer reduces the refractive index of the cladding layer, light is limited to propagate in the fiber core region, and the larger the refractive index difference of the fiber core and the cladding layer is, the more light is concentrated in the fiber core region, the larger the effective refractive index of the mode is, so that the effective refractive index of the fundamental mode is maximum for an optical fiber structure, and the p=4μ m d =3μ m d in the invention 1 The fundamental modes of the=3.3 μm structure at wavelengths of 1.55 μm and 2.025 μm are shown in fig. 3 (a), 3 (b). The structural parameters of the photonic crystal fiber are adjusted, the refractive index distribution of the section of the photonic crystal fiber is changed, the distance between the air hole and the fiber core is increased by increasing P, so that the refractive index of the fiber core is increased, the refractive index difference between the fiber core and the cladding is increased, and for the same wavelength, the mode field is concentrated at the center of the fiber core, and the effective refractive index is increased; by increasing the air hole diameter, the distance between the air hole and the core is reduced, resulting in a reduced core refractive index, a reduced core-cladding refractive index difference, and for the same wavelength, the mode field is more dispersed in the core center, and the effective refractive index is reduced, as shown in fig. 5, with an increase in d 1. And the dispersion and group velocity of the fiber are closely related to the change in effective refractive index. For the tellurate photonic crystal fiber designed by the invention, the influence of the diameter and the hole spacing of the air holes of the first layer on the distribution of the refractive index of the fiber core is the greatest, and the influence of other structural parameters is the greatestIn order to make the adjustment range of the first layer air hole diameter more free, the invention sets the hole spacing of all air holes of six layers to be uniform P, so we only study the first layer air hole diameter d 1 The effect of the hole pitch P on the chromatic dispersion, group velocity, effective refractive index and nonlinear coefficient of the photonic crystal fiber.
Group velocity matching process
By continuously adjusting the structural parameters, the change rule and the change range of the wavelength matched with the group velocity of 1.55 mu m are searched, so that the wavelength matched with the group velocity of 1.55 mu m is determined to be in a 2 mu m wave band when the ratio (namely the duty ratio) of the air hole diameter to the hole pitch is 75% -87% under the condition that all the air hole diameters are the same and the hole pitches are the same. Among them, when the hole pitch of all air holes is 4. Mu.m, and the hole diameter of all air holes is 3.3. Mu.m, it is preferable that the group velocity match of the band of 1.55. Mu.m and 2. Mu.m. Since the group 5 velocity is only slightly affected by the layer 2 to 6 air hole diameters, only the first layer air hole diameter was studied here, and can be ignored. As shown in fig. 4, the hole pitch p=4μm is determined, the diameters of the air holes of the layers 2 to 6 are d=3μm, and the size of the air hole diameter of the first layer is changed, so that the group velocity change and the matching wavelength displacement corresponding to each structural parameter are obvious. In the band range of fig. 4, for a certain wavelength, the group velocity decreases as the first layer air hole diameter increases; for a certain structure, the group velocity increases with wavelength and then decreases, and the curve is in a concave-convex shape. For group velocity matched fibers, the group velocity profile should be between two matched wavelengths to achieve group velocity matching, which is also a decision method in screening the structure of group velocity matched fibers.
By selecting the tellurate photonic crystal fiber designed by the invention, namely P=4mu m d =3mu m d 1=3.3 mu m, the change curve of the group velocity along with the wavelength can be obtained, as shown in figure 6, the wavelength matched with the group velocity of 1.55 mu m is 2.025 mu m, and the group velocities are 140.989m & mu s -1 The method comprises the steps of carrying out a first treatment on the surface of the The dispersion versus wavelength curve is shown in FIG. 7, from which it can be seen that there is a zero dispersion point between 1.55 μm and 2.025 μm, with 1.55 μm in the normal dispersion region, 2.025 μm in anomalous dispersion region, the dispersion difference between the two wavelengths being 78.73 ps.nm -1 ·km -1 The nonlinear coefficient at 1.55 μm was calculated to be 192.71W -1 km -1 The nonlinear coefficient at 2.025 μm is 143.58W -1 km -1 It can be seen that its non-linear coefficient is large, which has a large effect on its full cross-phase modulation. Zero dispersion points appear between the group velocity matched wavelengths because the group velocity is matched, the group velocity is concave-convex along the wavelength change curve, the slope of the group velocity along the wavelength change curve must have zero points between the two wavelengths, and the group velocity is beta 1 Reciprocal, beta 2 Is beta 1 With respect to the first derivative of ω, the dispersion parameter D is β 1 Regarding the first derivative of λ, there is a point where D is 0.
All air hole pitch P and first layer air hole diameter d were studied separately for the surrounding of group velocity matched photonic crystal fiber structure with structural parameters p=4μ m d =3μ m d 1=3.3 μm 1 Influence on the wavelength matching the group velocity of 1.55 μm. For different univariate structural parameters, there are two cases: first, p=4 μm, d=3 μm, and d is adjusted 1 The variation curve of the matching wavelength along with the diameter of the first layer air hole is shown in figure 8, and the formula lambda is obtained through fitting GVM ＝-0.021d 1 2 -0.173d 1 +2.824，λ GVM E (1.9,2.1); second, d=3 μm, d 1 The curve of the matching wavelength with the hole spacing of all air holes is shown in fig. 9, and the formula lambda is obtained by fitting GVM ＝-0.134P 2 +1.643P-2.411，λ GVM E (1.9,2.1). Therefore, the tellurate photonic crystal fiber designed by the invention can realize group velocity matching of 1.55 mu m wavelength and any wavelength of 2 mu m wave band, and when P=4 mu m and d=3 mu m, d is as follows 1 The adjusting range of (2) is about 3.0-3.7; when d=3 μm, d 1 When the value is =3.3 μm, the adjustment range of P is about 3.8 to 4.15 μm. And the diameters of the air holes of 2 to 6 layers can be properly adjusted according to the actual process.
Wavelength conversion process based on tellurate photonic crystal fiber in nonlinear ring mirror:
as shown in fig. 10, the wavelength converter of the present embodiment from 1.55 μm to 2 μm includes a first wavelength division multiplexer 101, a tellurate photonic crystal fiber 102 for realizing group velocity matching, a second wavelength division multiplexer 103, and a coupler 104; the first wavelength division multiplexer 101 has a first input/output port (connection port of an upper part of the first wavelength division multiplexer 101 in the drawing), a second input/output port (connection port of a lower right part of the first wavelength division multiplexer 101 in the drawing) for inputting pulse light of 1.55 μm band to the wavelength converter (connection port of a lower left part of the first wavelength division multiplexer 101 in the drawing), the second wavelength division multiplexer 103 has a third input/output port (connection port of an upper part of the second wavelength division multiplexer 103 in the drawing), a fourth input/output port (connection port of a lower left part of the second wavelength division multiplexer 103 in the drawing), and an output port (connection port of a lower right part of the first wavelength division multiplexer 103 in the drawing) for outputting pulse light of 1.55 μm band, the coupler 104 has an input port (connection port of a lower left part of the coupler 104 in the drawing) for outputting pulse light of 1.55 μm band as an output of the wavelength converter, the fifth input/output port (connection port of the fifth wavelength division multiplexer 104 in the drawing), and a sixth input port of the fifth wavelength division multiplexer in the drawing. The coupler 104 is connected with the first wavelength division multiplexer 101 and the second wavelength division multiplexer 103 through optical fibers, the first wavelength division multiplexer 101 is connected with the second wavelength division multiplexer 103 through optical fibers (tellurate photonic crystal fiber 102 can be directly adopted), and the first wavelength division multiplexer 101, tellurate photonic crystal fiber 102, the second wavelength division multiplexer 103 and the coupler 104 are connected into a ring shape. The structure and connection of the various parts of the wavelength converter are also defined by the flow direction of the following signals: the signal flow direction of the pump light pulse of the 1.55 mu m wave band is as follows: a first wavelength division multiplexer 101, a tellurate photonic crystal fiber 102, a second wavelength division multiplexer 103, and then flows out; the flow direction of light of 2 μm wave band entering the coupler is divided into two paths, one path is in sequence: coupler 104, first wavelength division multiplexer 101, tellurate photonic crystal fiber 102, second wavelength division multiplexer 103, then flow back to coupler 104, the other way is in order: a coupler 104, a second wavelength division multiplexer 103, a tellurate photonic crystal fiber 102, a first wavelength division multiplexer 101, and then back to the coupler 104.
When no input signal is present, the continuous light wave passes through the 3dB coupler 104 and is divided into two light beams with the same intensity and propagating in the clockwise and anticlockwise directions, the anticlockwise transmitted light beams generate pi/2 phase shift, then the two opposite transmitted light beams return to the 3dB coupler 104 after being transmitted along the annular mirror for one circle, and meanwhile the anticlockwise transmitted light beams generate pi/2 phase shift, so that the phase difference between the two light beams is pi, interference is cancelled, and no signal is output. When the first wavelength division multiplexer 101 inputs a strong pulse optical signal, and the strong pulse optical signal enters the annular mirror to propagate along the clockwise direction, cross phase modulation occurs between the first wavelength division multiplexer and the continuous wave in two directions in the tellurate photonic crystal fiber 102. The cross-phase modulation is negligible due to the severe walk-off effect of the counter-clockwise continuous wave and the input pulse. And the continuous waves in the clockwise direction cannot generate a walk-off effect due to group velocity matching, so that the high efficiency of cross phase modulation is ensured. When the phase shift of pi is generated by the intersection phase modulation of the clockwise continuous wave and the input pulse, the phase difference of the continuous wave in two directions is zero at the output end, and the output waveform is the same as the input pulse due to interference constructive, so that the conversion of the input pulse signal on the continuous wave is realized, namely the wavelength conversion is realized, if the phase difference is odd multiple of pi, interference cancellation occurs, and no output waveform exists.
For the present invention p=4 μm, d=3 μm, d 1 Tellurate photonic crystal fiber with 3.3 μm realizes group velocity matching of 1550nm and 2025nm, so we let 1550nm as input optical pulse signal and 2025nm as continuous wave. In the simulation, at lossWith 0, the input signal power is p=10w, and the continuous wave power is 0.01W. In order to achieve a phase shift of pi produced by cross-phase modulation, the total length L of the fiber in the loop (including tellurate photonic crystal fiber 102) is required to satisfy the following equation:
π＝2Pγ 12 L
wherein P is input signal power, L is optical fiber length, and gamma 12 For the nonlinear coefficient related to the cross-phase modulation, the nonlinear coefficient is calculated by the following formula: gamma=2n 2 /(λA eff ) Wherein n is 2 Is a non-linear refractive index, material dependent, typically constant,
is the effective mode field area. Non-linear coefficient calculation formula middle and gamma 12 Related n 2 And A eff Is related to cross-phase modulation and is calculated as follows:
wherein F is 1 And F 2 Electric field distribution of 1550nm and 2025nm, respectively, n 21 And n 22 Nonlinear coefficients of 1550nm and 2025nm, respectively. And for n 21 And n 22 In relation to materials, the TLX-based PCF herein has only two materials, one being TLX, with a nonlinear index of refraction of 5X 10 -19 m 2 One is air in the air hole, and the nonlinear coefficient is 0. Calculated γ= 166.32W -1 km -1 L= 0.9445m can be obtained. Therefore, at this time, as shown in fig. 11 (a) and 11 (b), it is apparent that the pulse waveform 11 (b) of the output light is identical to the input pulse signal 11 (a), and the output light pulse power is unchanged due to the loss of 0, and the conversion of the 1550nm pulse at the 2025nm wavelength is realized.
The wavelength conversion example is presented here to illustrate that the tellurate photonic crystal fiber designed by the present invention has high nonlinearity, and the efficiency of wavelength conversion is improved because the group velocity matching ensures the high efficiency of cross phase modulation, and the matching of the common communication window of 1.55 μm and the group velocity of 2 μm has the potential to become the next generation communication window, which provides a method for the next generation optical communication.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present invention and the scope of the claims, which are to be protected by the present invention.
Claims (8)
1. A wavelength converter of 1.55 mu m wave band to 2 mu m wave band, which is characterized by comprising a first wavelength division multiplexer, tellurate photonic crystal fiber for realizing group velocity matching, a second wavelength division multiplexer and a coupler; the first wavelength division multiplexer has a first input/output end, a second input/output end and an input port for inputting pulse light of 1.55 mu m wave band to the wavelength converter, the second wavelength division multiplexer has a third input/output port, a fourth input/output port and an output port for outputting pulse light of 1.55 mu m wave band, the coupler has an input port for inputting continuous light of 2 mu m wave band, an output port for outputting pulse light of 1.55 mu m wave band as output of the wavelength converter, a fifth input/output end and a sixth input/output end, the tellurate photonic crystal fiber is connected between the first input/output end and the third input/output port, the second input/output end is connected with the fifth input/output end, the fourth input/output port is connected with the sixth input/output end, the light of 2 mu m wave band is specifically light of 2.025 mu m wave band, and the coupler is a 3dB coupler.
2. The wavelength converter of claim 1, wherein the structure and connection of the sections of the wavelength converter is further defined by the flow direction of the following signals:
the signal flow direction of the pump light pulse with the wave band of 1.55 mu m is as follows: the first wavelength division multiplexer, tellurate photonic crystal fiber, the second wavelength division multiplexer and then flows out;
the flow direction of light of 2 μm wave band entering the coupler is divided into two paths, one path is in sequence: the coupler, the first wavelength division multiplexer, the tellurate photonic crystal fiber and the second wavelength division multiplexer are connected in sequence, and then flow back to the coupler, and the other path is as follows: the device comprises a coupler, a second wavelength division multiplexer, a tellurate photonic crystal fiber, a first wavelength division multiplexer and a back flow to the coupler.
3. The wavelength converter of claim 1, wherein the tellurate photonic crystal fiber has a core and a cladding each made of a base material of 60TeO2-20PbO-20PbCl2, the base material having a plurality of air holes disposed in parallel along the tellurate photonic crystal fiber axis; on any cross section of the tellurate photonic crystal fiber: the air holes are distributed in multiple layers along the axis of the tellurate photonic crystal fiber, the air holes of each layer are arranged into regular hexagons, the distance between the hole centers of any two adjacent air holes is P=4μm+/-0.25 μm, the diameter d1 of each air hole of the innermost layer is 3.0-3.7 μm, the diameter difference of any air hole of the innermost layer is within 0.5 μm, the diameter d of the rest of air holes is 3 μm+/-0.5 μm, or the distance P between the hole centers of any two adjacent air holes is 3.80-4.15 μm, the distance between the hole centers of any two adjacent air holes is within 0.725 μm, the diameter d1 of the air hole of the innermost layer is 3.3 μm+/-1.45 μm, and the diameter d of the rest of air holes is 3 μm+/-1.45 μm; the core is formed by the base material surrounded by circles formed between the centers of the innermost air holes, and the cladding is formed by the other base material and all air holes.
4. A wavelength converter according to claim 3, wherein in each regular hexagon there is an air hole at the intersection between any two adjacent sides.
5. A wavelength converter according to claim 3, wherein the distance between the centers of any two adjacent air holes is P = 4 μm, the diameter d1 of each air hole of the innermost layer is equal, d1 ranges from 3.0 to 3.7 μm, the diameter d of the remaining air holes is 3 μm, or the distance between the centers of any two adjacent air holes is equal, P ranges from 3.80 to 4.15 μm, the diameter d1 of each air hole of the innermost layer is 3.3 μm, and the diameter d of the remaining air holes is 3 μm.
6. A wavelength converter according to claim 3, wherein the diameter of the air holes of the innermost layer and the distance between the centers of any two adjacent air holes are further defined by the ratio K of the diameter of the air holes of the innermost layer to the distance between the centers of any two adjacent air holes, K ranging from 72% to 92%.
7. A wavelength converter according to claim 3, wherein for any one of the tellurate photonic crystal fibers, the size of the core diameter is at 2P min ～2P max Within, P min P max Respectively represent the minimum value and the maximum value of the distance between the hole centers of two adjacent air holes of the tellurate photonic crystal fiber.
8. The wavelength converter of claim 1, wherein the first wavelength division multiplexer, the tellurate photonic crystal fiber, the second wavelength division multiplexer, and the coupler are connected in a ring, and the length of the optical fiber contained in the ring conforms to the following formula:
π＝2Pγ 12 L
wherein P is input signal power, L is optical fiber length, and gamma 12 Is a nonlinear coefficient associated with cross-phase modulation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711013472.0A CN107728403B (en) | 2017-10-25 | 2017-10-25 | Wavelength converter with wavelength ranging from 1.55 mu m to 2 mu m |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711013472.0A CN107728403B (en) | 2017-10-25 | 2017-10-25 | Wavelength converter with wavelength ranging from 1.55 mu m to 2 mu m |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107728403A CN107728403A (en) | 2018-02-23 |
| CN107728403B true CN107728403B (en) | 2023-07-14 |
Family
ID=61212834
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711013472.0A Active CN107728403B (en) | 2017-10-25 | 2017-10-25 | Wavelength converter with wavelength ranging from 1.55 mu m to 2 mu m |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107728403B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112284567B (en) * | 2020-10-19 | 2021-09-21 | 东北大学 | Cascade soliton self-frequency-shift all-fiber sensing system and method for measuring sea water temperature and salt |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB0018802D0 (en) * | 2000-04-06 | 2000-09-20 | Marconi Caswell Ltd | Optical modulator with pre-determined frequency chirp |
| CN1397833A (en) * | 2002-08-15 | 2003-02-19 | 上海交通大学 | Multi-band rare-earth doped optical fibre amplifier |
| WO2012168400A1 (en) * | 2011-06-09 | 2012-12-13 | Universite Lille 1 - Sciences Et Technologies De Lille | Hybrid photonic crystal fiber |
| CN203014156U (en) * | 2012-12-18 | 2013-06-19 | 中国人民解放军国防科学技术大学 | High-power high-efficiency super-continuous spectrum light source |
| CN103502884A (en) * | 2011-03-14 | 2014-01-08 | Imra美国公司 | Broadband generation of mid IR, coherent continua with optical fibers |
| CN106255907A (en) * | 2014-03-25 | 2016-12-21 | Nkt光子学有限公司 | Microstructured optical fibers and super continuum source |
| CN107238415A (en) * | 2017-07-27 | 2017-10-10 | 中国地质大学（武汉） | For detecting the temperature of fully distributed fiber and the sensor of vibration position |
| CN207529075U (en) * | 2017-10-25 | 2018-06-22 | 中国地质大学（武汉） | A kind of 1.55 mu m waveband to 2 mu m wavebands wavelength shifter |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3860201B2 (en) * | 2003-08-13 | 2006-12-20 | 日本電信電話株式会社 | Optical fiber manufacturing method |
| GB2408811B (en) * | 2003-12-06 | 2005-11-23 | Bookham Technology Plc | Optical Modulator |
-
2017
- 2017-10-25 CN CN201711013472.0A patent/CN107728403B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB0018802D0 (en) * | 2000-04-06 | 2000-09-20 | Marconi Caswell Ltd | Optical modulator with pre-determined frequency chirp |
| CN1397833A (en) * | 2002-08-15 | 2003-02-19 | 上海交通大学 | Multi-band rare-earth doped optical fibre amplifier |
| CN103502884A (en) * | 2011-03-14 | 2014-01-08 | Imra美国公司 | Broadband generation of mid IR, coherent continua with optical fibers |
| WO2012168400A1 (en) * | 2011-06-09 | 2012-12-13 | Universite Lille 1 - Sciences Et Technologies De Lille | Hybrid photonic crystal fiber |
| CN203014156U (en) * | 2012-12-18 | 2013-06-19 | 中国人民解放军国防科学技术大学 | High-power high-efficiency super-continuous spectrum light source |
| CN106255907A (en) * | 2014-03-25 | 2016-12-21 | Nkt光子学有限公司 | Microstructured optical fibers and super continuum source |
| CN107238415A (en) * | 2017-07-27 | 2017-10-10 | 中国地质大学（武汉） | For detecting the temperature of fully distributed fiber and the sensor of vibration position |
| CN207529075U (en) * | 2017-10-25 | 2018-06-22 | 中国地质大学（武汉） | A kind of 1.55 mu m waveband to 2 mu m wavebands wavelength shifter |
Non-Patent Citations (2)
| Title |
|---|
| High-performance TFTs with Si nanowire channels enhanced by metal-induced lateral crystallization;C.-J.SU等;IEEE;第27卷(第7期);582-584 * |
| 超连续谱注入光参量放大法产生超短中红外激光脉冲技术研究;邓颖;中国优秀硕士学位论文全文数据库;I135-18 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107728403A (en) | 2018-02-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Notomi et al. | Waveguides, resonators and their coupled elements in photonic crystal slabs | |
| Niang et al. | Spatial beam self-cleaning and supercontinuum generation with Yb-doped multimode graded-index fiber taper based on accelerating self-imaging and dissipative landscape | |
| US9577401B2 (en) | Systems and methods of achieving high brightness infrared fiber parametric amplifiers and light sources | |
| Israk et al. | Ring-based coil structure photonic crystal fiber for transmission of orbital angular momentum with large bandwidth: outline, investigation and analysis | |
| Chaudhari et al. | Chalcogenide core tellurite cladding composite microstructured fiber for nonlinear applications | |
| CN104932171A (en) | Micro-annular waveguide optical device used for generating optical frequency comb | |
| WO2007097337A1 (en) | Nonlinear optical fiber, nonlinear optical device, and optical signal processor | |
| CN109073824B (en) | Coupled multi-core optical fiber and optical transmission system including the same | |
| Hassan et al. | Numerical analysis of circular core shaped photonic crystal fiber for orbital angular momentum with efficient transmission | |
| Li et al. | Nearly chirp-and pedestal-free pulse compression in nonlinear fiber Bragg gratings | |
| CN101271243B (en) | Optical continuum source including light generation beyond wavelength edges of continuum | |
| US7339721B1 (en) | Optical fiber light source based on third-harmonic generation | |
| Al-Zahrani et al. | Novel design of dual guided photonic crystal fiber for large capacity transmission in high-speed optics communications with supporting good quality OAM and LP modes | |
| CN107728403B (en) | Wavelength converter with wavelength ranging from 1.55 mu m to 2 mu m | |
| CA2843546A1 (en) | Wave vector matched resonator and bus waveguide system | |
| Cheshmberah et al. | Supercontinuum generation in PCF with As 2 S 3/Ge 20 Sb 15 Se 65 Chalcogenide core pumped at third telecommunication wavelengths for WDM | |
| Mustafa et al. | Dispersion compensation in silica doped fiber using soliton transmission technique over cascaded FBG | |
| Marconi et al. | Ultra-broadband two-pump optical parametric amplifier in tellurite waveguides with engineered dispersion | |
| WO2004083954A1 (en) | Wavelength converter | |
| Masunda et al. | Modal properties of a varied high indexed large core 4-mode photonic crystal fiber | |
| Maji et al. | Studies of the modal properties of circularly photonic crystal fiber (C-PCF) for high power applications | |
| Jain et al. | Design and analysis of single-mode tellurite photonic crystal fibers for stimulated Brillouin scattering based slow-light generation | |
| CN107632337B (en) | Tellurate group velocity matching photonic crystal fiber | |
| CN207529075U (en) | A kind of 1.55 mu m waveband to 2 mu m wavebands wavelength shifter | |
| Peng et al. | Soliton-sinc optical pulse propagation in the presence of high-order effects |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |