CN115097658A - Temperature tuning optical fiber filter - Google Patents

Temperature tuning optical fiber filter Download PDF

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Publication number
CN115097658A
CN115097658A CN202210825133.7A CN202210825133A CN115097658A CN 115097658 A CN115097658 A CN 115097658A CN 202210825133 A CN202210825133 A CN 202210825133A CN 115097658 A CN115097658 A CN 115097658A
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temperature
birefringence
polarization
fiber
maintaining
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Inventor
吕志国
蒋淞聿
李泽
王微微
阿荣
谭政
李允明
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Inner Mongolia University
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Inner Mongolia University
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    • 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
    • G02F1/01—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 for the control of the intensity, phase, polarisation or colour 
    • G02F1/0147—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 for the control of the intensity, phase, polarisation or colour  based on thermo-optic effects
    • 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
    • G02F1/01—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 for the control of the intensity, phase, polarisation or colour 
    • G02F1/011—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 for the control of the intensity, phase, polarisation or colour  in optical waveguides, not otherwise provided for in this subclass
    • G02F1/0115—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 for the control of the intensity, phase, polarisation or colour  in optical waveguides, not otherwise provided for in this subclass in optical fibres
    • 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
    • G02F1/01—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 for the control of the intensity, phase, polarisation or colour 
    • G02F1/0121—Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
    • 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
    • G02F1/01—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 for the control of the intensity, phase, polarisation or colour 
    • G02F1/0136—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 for the control of the intensity, phase, polarisation or colour  for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)

Abstract

The invention discloses a temperature tuning optical fiber filter, which relates to the technical field of optical fiber filters and comprises the following components: a linear polarizer for obtaining linearly polarized light; one end of the first high birefringence polarization maintaining fiber is welded with the linear polarizer at an angle of 45 degrees and is used for enabling linearly polarized light to generate polarization state rotation; one end of the temperature-sensitive birefringent crystal is welded with the other end of the first high-birefringence polarization maintaining fiber and is used for enabling the linearly polarized light to generate polarization state rotation; one end of the second high-birefringence polarization-maintaining fiber is welded with the other end of the temperature-sensitive birefringence crystal and is used for enabling the linearly polarized light to generate polarization state rotation; the linear analyzer is welded with the other end of the second high-birefringence polarization-maintaining optical fiber at an angle of 45 degrees and is used for converting the polarization state rotation of the linearly polarized light into amplitude modulation to complete filtering; and the adjusting system is used for adjusting the temperatures of the first high-birefringence polarization maintaining fiber, the temperature-sensitive birefringence crystal and the second high-birefringence polarization maintaining fiber in real time to complete dynamic tuning of the central wavelength and the spectral bandwidth of the output light.

Description

Temperature tuning optical fiber filter
Technical Field
The invention relates to the technical field of optical fiber filters, in particular to a temperature tuning optical fiber filter.
Background
With the development of laser technology, optical filters have become the subject of research of many researchers as indispensable basic tools in laser technology. Since the development of optical filtering technology, different types of optical filters have been developed based on different theoretical bases, such as Fabry-Perot filters, multilayer dielectric film filters, fused-cone optical fiber filters, mach-zehnder interference filters based on the optical interference principle, bulk grating filters, arrayed waveguide grating filters, fiber grating filters, and acousto-optic tunable filters based on the grating principle.
In the rapid development of optical fiber communication and laser technology, there is an increasing demand for dynamic tuning performance of optical filters, for example, in an optical fiber communication network, with the rapid development of Dense Wavelength Division Multiplexing (DWDM), the spacing between channels is narrower and narrower, the propagation speed of channels is faster and faster, and the optical communication network is evolving from an original static WDM system to an all-optical communication network with high-speed dynamic routing, so that there is an increasing demand for dynamic tuning performance and tuning speed of optical filters.
In the positive dispersion region, the generation of ultrashort pulse laser is mainly influenced by parameters such as nonlinear phase shift, group velocity dispersion and spectral filtering bandwidth, wherein the spectral bandwidth plays an important role in outputting single pulse energy, pulse width, average power and the like of the laser.
Besides being applied to optical fiber communication and laser technology, the optical filter is also an important component and a production tool of many civil high-tech products, such as photoelectric display in televisions, cameras and mobile phones, and is of great importance in various fields such as aviation, aerospace, satellite technology and the like.
The optical filters are used as important filtering devices, each filter has unique output light central wavelength and spectral bandwidth, dynamic tuning cannot be realized, and the optical filters under the spectral bandwidths need to be replaced for meeting the requirements of different spectral bandwidths, so that the practicability of the optical filters is reduced; in addition, the main production mode of the optical filter is a coating technology, and the production process is complex and high in cost.
A birefringent filter is a type of filter that uses a birefringent medium to introduce a phase delay. The modulation of the transmission spectrum signal is realized by adjusting the birefringence effect in the filter, and the wavelength is further tuned.
Bernard liot (Bernard Lyot) proposes a birefringent filter: the Lyot birefringent filter has the basic structure as follows: a birefringent plate is arranged between two polarizers with the same transmission direction, light is changed into linearly polarized light after passing through the polarizers and is incident on the birefringent plate, the linearly polarized light is decomposed into two beams of light with mutually vertical polarization directions, phase difference is generated in the transmission process of the two beams of light, interference phenomenon is generated through an analyzer, and wavelength selective transmission is caused; the Lyot birefringent filter can change the birefringence by inserting different birefringent plates, thereby realizing the tuning of the spectral bandwidth.
However, this requires the filter to be recombined and recalibrated, which is inconvenient to operate, and meanwhile, the transmission line of the Lyot birefringent filter is approximately periodic, and the ratio of the transmission bandwidth to the free spectral range is too large to be used for filtering light directly, and in addition, the Lyot birefringent filter has the disadvantages of low peak transmittance, small tuning range, high temperature control precision requirement, and the like.
Disclosure of Invention
The invention provides a temperature tuning optical fiber filter aiming at the problems that the existing optical filter is difficult to realize dynamic tuning of output optical wavelength and spectral bandwidth and the defects of a Lyot type filter, which specifically comprises the following steps:
and the linear polarizer is used for obtaining linearly polarized light from the light.
And one end of the first high-birefringence polarization-maintaining fiber is welded with one end of the linear polarizer at an angle of 45 degrees and is used for enabling the linearly polarized light to generate a first polarization state rotation.
And one end of the temperature-sensitive birefringent crystal is welded with the other end of the first high-birefringence polarization maintaining fiber and is used for enabling the linearly polarized light which generates the first polarization state rotation to generate the second polarization state rotation.
And one end of the second high-birefringence polarization-maintaining fiber is welded with the other end of the temperature-sensitive birefringent crystal and is used for enabling the linearly polarized light which generates the second polarization rotation to generate the third polarization rotation.
And the linear analyzer is welded with the other end of the second high-birefringence polarization-maintaining fiber at 45 degrees and is used for converting the polarization state rotation of the linearly polarized light which generates the third polarization state rotation into amplitude modulation to finish filtering.
And the adjusting system is used for adjusting the temperatures of the first high-birefringence polarization maintaining fiber, the temperature-sensitive birefringence crystal and the second high-birefringence polarization maintaining fiber in real time, so that the birefringence indexes of the first high-birefringence polarization maintaining fiber, the temperature-sensitive birefringence crystal and the second high-birefringence polarization maintaining fiber are adjusted in real time, and the dynamic tuning of the central wavelength and the spectral bandwidth of the output light is completed.
Further, the adjustment system comprises:
and the first temperature adjusting module is arranged on the first high-birefringence polarization maintaining optical fiber and is used for adjusting and controlling the temperature of the first high-birefringence polarization maintaining optical fiber.
And the second temperature adjusting module is arranged on the temperature-sensitive birefringent crystal and used for adjusting and controlling the temperature of the temperature-sensitive birefringent crystal.
And the third temperature adjusting module is arranged on the second high-birefringence polarization maintaining optical fiber and used for adjusting and controlling the temperature of the second high-birefringence polarization maintaining optical fiber.
And the three high-precision temperature sensors are respectively arranged in the three high-power intensive spiral heating resistors and are used for monitoring the temperatures of the first high-birefringence polarization-maintaining optical fiber, the temperature-sensitive birefringence crystal and the second high-birefringence polarization-maintaining optical fiber.
And the control unit is used for receiving the data of the high-precision temperature sensor, processing and operating the data, and controlling the first temperature adjusting module, the second temperature adjusting module and the third temperature adjusting module to perform coarse adjustment and fine adjustment on the output light characteristics according to the calculation result.
Further, the first temperature adjustment module, the second temperature adjustment module and the third temperature adjustment module each include:
and the heating length of the high-power dense spiral heating resistor is the same as the lengths of the first high-birefringence polarization-maintaining optical fiber, the temperature-sensitive birefringence crystal and the second high-birefringence polarization-maintaining optical fiber which correspond to the high-power dense spiral heating resistor.
And the air-cooled small refrigerator is electrically connected with the high-power intensive spiral heating resistor.
And the temperature control module is electrically connected with the high-power intensive spiral heating resistor and comprises a rapid heating-up function, a rapid cooling-down function and a temperature maintaining function.
Further, the maximum realization temperatures of the first temperature adjusting module, the second temperature adjusting module and the third temperature adjusting module are all lower than the maximum bearing temperatures of the first high birefringence polarization maintaining fiber, the temperature-sensitive birefringence crystal and the second high birefringence polarization maintaining fiber.
Further, the length of the second high birefringence polarization maintaining fiber is equal to the length of the first high birefringence polarization maintaining fiber, and the fast axis direction of the second high birefringence polarization maintaining fiber is perpendicular to the fast axis direction of the first high birefringence polarization maintaining fiber.
Further, the transmission vibration direction of the line analyzer is parallel to that of the line polarizer.
Further, the lengths of the first high birefringence polarization maintaining fiber and the second high birefringence polarization maintaining fiber are equal, and the initial birefringence rates are both 3.6 × 10 -4 The coefficient of variation of birefringence with temperature was-1X 10 -7 /℃。
Further, the temperature-sensitive birefringent crystal has a cylindrical shape, has a radius equal to the radius of the first high birefringent polarization maintaining fiber and the second high birefringent polarization maintaining fiber, has a length of 0.2m, exhibits isotropy at a fixed temperature, and has a coefficient of variation of birefringence with temperatureIs-1 x 10 -5 /℃。
Compared with the prior art, the invention provides a temperature tuning optical fiber filter, which has the beneficial effects that:
the temperature tuning optical fiber filter provided by the invention has the advantages that the fast axis directions of the first high-birefringence polarization maintaining optical fiber and the second high-birefringence polarization maintaining optical fiber are vertical, the lengths are the same, the first temperature adjusting module and the third temperature adjusting module which act on the first high-birefringence polarization maintaining optical fiber and the second high-birefringence polarization maintaining optical fiber can simultaneously generate reverse temperature differences to tune to the same phase difference change direction, the dynamic tuning speed is accelerated, and meanwhile, under the addition of an adjusting system, the three temperature control modules simultaneously work, and the dynamic tuning speed is accelerated; in summary, the temperature tunable optical fiber filter provided by the invention can realize dynamic tuning of the central wavelength of output light by changing temperature through the temperature adjusting module; the dynamic tuning of the spectral bandwidth can be realized by carrying out temperature variation through the temperature control module.
Drawings
Fig. 1 is a schematic structural diagram of a temperature-tunable optical fiber filter according to the present invention;
FIG. 2 is a schematic structural diagram of a temperature control module according to an embodiment of the present invention;
FIG. 3 is a graph of the transmittance of the output light at a temperature difference of 0 deg.C, 30 deg.C and 100 deg.C under coarse tuning in the embodiment of the present invention;
FIG. 4 is a graph showing the relationship between the spectral bandwidth and the temperature difference when the temperature difference is changed from 30 ℃ to 100 ℃ in the embodiment of the present invention;
FIG. 5 is a graph of the transmittance of the output light at the temperature difference of 0 deg.C, 5 deg.C and 10 deg.C, respectively, after fine tuning according to the embodiment of the present invention;
FIG. 6 is a graph showing the wavelength adjustment accuracy of output light versus the length of a birefringent fiber according to an embodiment of the present invention.
In the figure: 1. the device comprises a linear polarizer, 2, a first high-birefringence polarization-maintaining optical fiber, 3, a temperature-sensitive type birefringent crystal, 4, a second high-birefringence polarization-maintaining optical fiber, 5, a linear analyzer, 6, a first temperature adjusting module, 7, a second temperature adjusting module, 8, a third temperature adjusting module, 9, a high-power intensive spiral heating resistor, 10, an air-cooled small refrigerator, 11, a temperature control module, 12, an adjusting system and 13, and a high-precision temperature sensor.
Detailed Description
The following describes the embodiments of the present invention with reference to fig. 1 to 6. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
Example 1: referring to fig. 1, the temperature-tuned optical fiber filter provided by the present invention specifically includes: a linear polarizer 1 for obtaining linearly polarized light from light; one end of the first high-birefringence polarization-maintaining fiber 2 is welded with one end of the linear polarizer 1 at an angle of 45 degrees and is used for enabling linearly polarized light to generate first polarization state rotation; one end of the temperature-sensitive birefringent crystal 3 is welded with the other end of the first high-birefringence polarization maintaining fiber 2 and is used for enabling linearly polarized light which generates the first polarization state rotation to generate the second polarization state rotation; one end of the second high-birefringence polarization-maintaining fiber 4 is welded with the other end of the temperature-sensitive birefringence crystal 3 and is used for enabling linearly polarized light which generates the second polarization rotation to generate a third polarization rotation; the linear analyzer 5 is welded with the other end of the second high-birefringence polarization-maintaining fiber 4 at an angle of 45 degrees and is used for converting the polarization rotation of the linearly polarized light which generates the third polarization rotation into amplitude modulation to complete filtering; and the adjusting system 12 is configured to adjust the temperatures of the first high birefringent polarization maintaining fiber 2, the temperature sensitive birefringent crystal 3, and the second high birefringent polarization maintaining fiber 4 in real time, so as to adjust the birefringence of the first high birefringent polarization maintaining fiber 2, the temperature sensitive birefringent crystal 3, and the second high birefringent polarization maintaining fiber 4 in real time, and complete dynamic tuning of the central wavelength and the spectral bandwidth of the output light.
In the present embodiment, the adjustment system 12 includes: the first temperature adjusting module 6 is arranged on the first high-birefringence polarization maintaining fiber 2 and used for adjusting and controlling the temperature of the first high-birefringence polarization maintaining fiber 2; the second temperature adjusting module 7 is arranged on the temperature-sensitive birefringent crystal 3 and used for adjusting and controlling the temperature of the temperature-sensitive birefringent crystal 3; the third temperature adjusting module 8 is arranged on the second high-birefringence polarization maintaining fiber 4 and used for adjusting and controlling the temperature of the second high-birefringence polarization maintaining fiber 4; the three high-precision temperature sensors 13 are respectively arranged in the three high-power intensive spiral heating resistors 9 and used for monitoring the temperatures of the first high-birefringence polarization-maintaining optical fiber 2, the temperature-sensitive birefringence crystal 3 and the second high-birefringence polarization-maintaining optical fiber 4; and the control unit is used for receiving the data of the high-precision temperature sensor 13, performing data processing and operation, and controlling the first temperature adjusting module 6, the second temperature adjusting module 7 and the third temperature adjusting module 8 to perform coarse adjustment and fine adjustment on the output light characteristics according to the calculation result.
In this embodiment, the first temperature adjustment module 6, the second temperature adjustment module 7, and the third temperature adjustment module 8 each include: the high-power intensive spiral heating resistor 9 has the same heating length as the first high-birefringence polarization-maintaining optical fiber 2, the temperature-sensitive birefringence crystal 3 and the second high-birefringence polarization-maintaining optical fiber 4 which correspond to the high-power intensive spiral heating resistor; the air-cooled small refrigerating machine 10 is electrically connected with the high-power intensive spiral heating resistor 9; and the temperature control module 11 is electrically connected with the high-power intensive spiral heating resistor 9, and the temperature control module 11 comprises a rapid heating-up function, a rapid cooling-down function and a temperature maintaining function.
In this embodiment, the maximum implementation temperatures of the first temperature adjustment module 6, the second temperature adjustment module 7, and the third temperature adjustment module 8 are all lower than the maximum bearing temperatures of the first high birefringent polarization-maintaining fiber 2, the temperature-sensitive birefringent crystal 3, and the second high birefringent polarization-maintaining fiber 4.
In this embodiment, the length of the second high birefringence polarization-maintaining fiber 4 is equal to the length of the first high birefringence polarization-maintaining fiber 2, and the fast axis direction of the second high birefringence polarization-maintaining fiber 4 is perpendicular to the fast axis direction of the first high birefringence polarization-maintaining fiber 2.
In the present embodiment, the transmission direction of the line analyzer 5 is parallel to the transmission direction of the line polarizer 1.
In the present embodiment, the first high birefringence polarization-maintaining fiber 2 and the second high birefringence polarization-maintaining fiber 4 have the same length, and the initial birefringence is 3.6 × 10 -4 The coefficient of variation of birefringence with temperature was-1X 10 -7 /℃。
In this embodimentThe temperature-sensitive birefringent crystal 3 has a cylindrical shape, has a radius equal to the radius of the first high birefringent polarization maintaining fiber 2 and the second high birefringent polarization maintaining fiber 4, has a length of 0.2m, exhibits isotropy at a constant temperature, and has a coefficient of variation of birefringence with temperature of-1 × 10 -5 /℃。
Specifically, the linear polarizer 1, the first high birefringence polarization maintaining fiber 2, the temperature sensitive birefringence crystal 3, the second high birefringence polarization maintaining fiber 4 and the linear analyzer 5 are sequentially connected, the first temperature adjusting module 6, the second temperature adjusting module 7 and the third temperature adjusting module 8 respectively act on the first high birefringence polarization maintaining fiber 2, the temperature sensitive birefringence crystal 3 and the second high birefringence polarization maintaining fiber 4, phase difference is generated through birefringence effect to cause polarization state rotation depending on wavelength, and the linear analyzer 5 converts the polarization state rotation related to wavelength into amplitude modulation to achieve filtering effect.
The linear polarizer 1 is welded with one end of the first high-birefringence polarization-maintaining optical fiber 2 at an angle of 45 degrees, so that linearly polarized light penetrating through the linear polarizer 1 is decomposed in two polarization directions of a fast axis and a slow axis of the first high-birefringence polarization-maintaining optical fiber 2; the second high birefringence polarization-maintaining fiber 4 is welded with one end of the linear analyzer 5 at an angle of 45 degrees, so that linearly polarized light in two polarization directions of a fast axis and a slow axis of the first high birefringence polarization-maintaining fiber 2 and the second high birefringence polarization-maintaining fiber 4 is synthesized into elliptically polarized light.
The temperature-sensitive birefringent crystal 3 is cylindrical, has the same radius as the first high birefringent polarization maintaining fiber 2 and the second high birefringent polarization maintaining fiber 4, has a length of 0.2m, is isotropic at a fixed temperature, and has a length of 0.1m for both the first high birefringent polarization maintaining fiber 2 and the second high birefringent polarization maintaining fiber 4.
The temperature control module consists of a high-power intensive spiral heating resistor 9, an air-cooled small refrigerator 10 and a temperature control module 11; the temperature control module has the functions of realizing rapid temperature rise and rapid temperature fall and maintaining the temperature unchanged, and can change the temperature rapidly to induce the birefringence effect. The highest temperature of the temperature control module is lower than the highest bearing temperature of the first high-birefringence polarization maintaining fiber 2, the temperature sensitive type birefringence crystal 3 and the second high-birefringence polarization maintaining fiber 4.
The coefficient of variation of birefringence with temperature of the temperature-sensitive birefringent crystal 3 is-1X 10 -5 The temperature is higher than the temperature, the birefringence is generated when the temperature is changed, the temperature induced birefringence effect is obvious, the central wavelength and the spectral bandwidth of the output light are greatly changed, and the temperature induced birefringence effect is used as a rough adjusting part of the temperature tuning optical fiber filter.
The first high birefringence polarization-maintaining fiber 2 and the second high birefringence polarization-maintaining fiber 4 have a coefficient of variation of birefringence with temperature of-1 × 10 -7 The temperature changes to generate very small birefringence, the temperature induced birefringence effect is not obvious, and the central wavelength and the spectral bandwidth of output light change very little and are used as the fine tuning part of the temperature tuning optical fiber filter.
The temperature controllers of the first temperature adjusting module 6, the second temperature adjusting module 7 and the third temperature adjusting module 8 are connected to the same adjusting system 12, and the adjusting system 12 is composed of a control unit and a high-precision temperature sensor 13. The control unit calculates according to the output light characteristics to be realized, the coarse tuning and the fine tuning of the filter act simultaneously, and the dynamic tuning speed is high.
The high-precision temperature sensor 13 is arranged in the high-power intensive spiral heating resistor 9, transmits the temperatures of the first high-birefringence polarization maintaining fiber 2, the temperature-sensitive birefringence crystal 3 and the second high-birefringence polarization maintaining fiber 4 to the control unit in real time, and continuously corrects errors generated in the temperature changing process.
Referring to fig. 3, when the second temperature adjustment module 7 acting on the temperature-sensitive birefringent crystal 3 works, the temperature-induced birefringence effect is significant, and the curve of the transmission coefficient of the output light changes greatly; the change curve of the transmission coefficient of the output light at 0 ℃ is a straight line at 1, because when the three temperature control modules do not work, the first high-birefringence polarization-maintaining optical fiber 2 and the second high-birefringence polarization-maintaining optical fiber 4 are equal in length and vertical in the fast axis direction, the generated phase difference is offset, and no rotation of the polarization state exists; the spectral bandwidth at the central wavelength of output light of 1017nm at 30 ℃ is 8.8nm, and the spectral bandwidth at the central wavelength of output light of 1015nm at 100 ℃ is 2.7nm, so that the output light has obvious changes in the central wavelength and the spectral bandwidth as a rough adjusting part of the temperature tuning optical fiber filter.
Referring to fig. 4, real points are output analog data, and are connected to form a graph of the variation of the spectral bandwidth and the temperature difference; the temperature difference is changed from 30 ℃ to 100 ℃, and the spectral bandwidth is changed from 8.5nm to 2.5nm, so that the spectral bandwidth of the temperature-tuned optical fiber filter obviously changes along with the temperature difference.
Referring to fig. 5, when the first temperature adjustment module 6 and the third temperature adjustment module 8 acting on the first high birefringent polarization maintaining fiber 2 and the second high birefringent polarization maintaining fiber 4 work, since the birefringence coefficients of the first high birefringent polarization maintaining fiber 2 and the second high birefringent polarization maintaining fiber 4 are very small with temperature, the temperature induced birefringence effect is not obvious, and the fiber is used as a fine tuning part of the temperature tuned fiber filter, fig. 5 is a curve of the transmission coefficient of output light under the fine tuning effect, the spectral bandwidth is basically unchanged, and the central wavelength of the output light has very small change.
Example 2: referring to fig. 6, a difference of the temperature tunable optical fiber filter provided by the present invention from embodiment 1 is that the lengths of the first high birefringent polarization maintaining fiber 2 and the second high birefringent polarization maintaining fiber 4 directly affect the adjustment accuracy of the temperature tunable optical fiber filter, and the temperature tunable optical fiber filter with different lengths of the first high birefringent polarization maintaining fiber 2 and the second high birefringent polarization maintaining fiber 4 can be selected according to requirements.
In summary, it can be seen that the temperature tunable optical fiber filter provided by the present invention has the following beneficial effects:
(1) the temperature tuning optical fiber filter provided by the invention can realize dynamic tuning of the central wavelength of output light by changing the temperature through the temperature adjusting module; the dynamic tuning of the spectral bandwidth can be realized by carrying out temperature variation through the temperature control module.
(2) The temperature tuning optical fiber filter provided by the invention can be divided into a coarse tuning part and a fine tuning part, and higher precision is ensured.
(3) When the first temperature adjusting module, the second temperature adjusting module and the third temperature adjusting module of the temperature tuning optical fiber filter do not work, the filter does not play a role in filtering, and the control is simple and reliable.
(4) The first high-birefringence polarization-maintaining fiber and the second high-birefringence polarization-maintaining fiber of the temperature-tuned fiber filter provided by the invention have vertical fast axis directions and same lengths, and the first temperature adjusting module and the third temperature adjusting module which act on the first high-birefringence polarization-maintaining fiber and the second high-birefringence polarization-maintaining fiber can simultaneously generate reverse temperature differences to tune to the same phase difference change direction, so that the dynamic tuning speed is accelerated, and meanwhile, under the action of an adjusting system, the three temperature control modules simultaneously work, so that the dynamic tuning speed is accelerated.
(5) The adjusting system of the temperature tuning optical fiber filter can feed back the temperatures of the first high-birefringence polarization maintaining optical fiber, the temperature sensitive type birefringence crystal and the second high-birefringence polarization maintaining optical fiber in real time, can continuously correct errors and improve the filtering precision.
(6) The temperature-tuned optical fiber filter provided by the invention can be combined with other types of filters to correct errors possibly generated by the other types of filters.
(7) The temperature-tuned optical fiber filter provided by the invention has the advantages of simple manufacturing process, low cost and cheap and easily-obtained optical components.
(8) The lengths of the first high-birefringence polarization maintaining fiber and the second high-birefringence polarization maintaining fiber of the temperature tuning optical fiber filter provided by the invention can directly influence the dynamic tuning precision of the temperature control module, and the temperature tuning optical fiber filter with different lengths of the first high-birefringence polarization maintaining fiber and the second high-birefringence polarization maintaining fiber can be selected according to requirements.
The above-mentioned embodiments are only preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, and any simple modifications or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims (8)

1. A temperature-tuned fiber optic filter, comprising:
a linear polarizer (1) for obtaining linearly polarized light from light;
one end of the first high-birefringence polarization-maintaining fiber (2) is welded with one end of the linear polarizer (1) at an angle of 45 degrees and is used for enabling the linearly polarized light to generate a first polarization state rotation;
one end of the temperature-sensitive birefringent crystal (3) is welded with the other end of the first high-birefringence polarization-maintaining fiber (2) and is used for enabling the linearly polarized light which generates the first polarization state rotation to generate the second polarization state rotation;
one end of the second high-birefringence polarization-maintaining fiber (4) is welded with the other end of the temperature-sensitive birefringent crystal (3) and is used for enabling the linearly polarized light which generates the second polarization rotation to generate a third polarization rotation;
the linear analyzer (5) is welded with the other end of the second high-birefringence polarization-maintaining fiber (4) at 45 degrees and is used for converting the polarization state rotation of the linearly polarized light which generates the third polarization state rotation into amplitude modulation to complete filtering;
and the adjusting system (12) is used for adjusting the temperatures of the first high-birefringence polarization-maintaining fiber (2), the temperature-sensitive birefringence crystal (3) and the second high-birefringence polarization-maintaining fiber (4) in real time, so that the birefringence indexes of the first high-birefringence polarization-maintaining fiber (2), the temperature-sensitive birefringence crystal (3) and the second high-birefringence polarization-maintaining fiber (4) are adjusted in real time, and the dynamic tuning of the central wavelength and the spectral bandwidth of the output light is completed.
2. A temperature-tuned fiber filter according to claim 1, wherein said conditioning system (12) comprises:
the first temperature adjusting module (6) is arranged on the first high-birefringence polarization maintaining optical fiber (2) and is used for adjusting and controlling the temperature of the first high-birefringence polarization maintaining optical fiber (2);
the second temperature adjusting module (7) is arranged on the temperature-sensitive birefringent crystal (3) and is used for adjusting and controlling the temperature of the temperature-sensitive birefringent crystal (3);
the third temperature adjusting module (8) is arranged on the second high-birefringence polarization-maintaining optical fiber (4) and is used for adjusting and controlling the temperature of the second high-birefringence polarization-maintaining optical fiber (4);
three high-precision temperature sensors (13) respectively arranged in the three high-power intensive spiral heating resistors (9) and used for monitoring the temperatures of the first high-birefringence polarization maintaining optical fiber (2), the temperature-sensitive birefringence crystal (3) and the second high-birefringence polarization maintaining optical fiber (4);
and the control unit is used for receiving the data of the high-precision temperature sensor (13), processing and operating the data, and controlling the first temperature adjusting module (6), the second temperature adjusting module (7) and the third temperature adjusting module (8) to perform coarse adjustment and fine adjustment on the output light characteristics according to the calculation result.
3. A temperature-tuned fiber filter according to claim 2, wherein:
the first temperature regulation module (6), the second temperature regulation module (7) and the third temperature regulation module (8) each comprise:
the heating length of the high-power intensive spiral heating resistor (9) is the same as the lengths of the first high-birefringence polarization-maintaining optical fiber (2), the temperature-sensitive birefringence crystal (3) and the second high-birefringence polarization-maintaining optical fiber (4) which correspond to the high-power intensive spiral heating resistor;
the air-cooled small refrigerator (10) is electrically connected with the high-power intensive spiral heating resistor (9);
the temperature control module (11) is electrically connected with the high-power dense spiral heating resistor (9), and the temperature control module (11) comprises a rapid heating-up function, a rapid cooling-down function and a temperature maintaining function.
4. A temperature-tuned fiber optic filter according to claim 2, wherein:
the maximum realization temperatures of the first temperature adjusting module (6), the second temperature adjusting module (7) and the third temperature adjusting module (8) are all lower than the maximum bearing temperatures of the first high-birefringence polarization maintaining fiber (2), the temperature-sensitive birefringence crystal (3) and the second high-birefringence polarization maintaining fiber (4).
5. A temperature-tuned fiber optic filter according to claim 1, wherein:
the length of the second high-birefringence polarization-maintaining fiber (4) is equal to that of the first high-birefringence polarization-maintaining fiber (2), and the fast axis direction of the second high-birefringence polarization-maintaining fiber (4) is perpendicular to that of the first high-birefringence polarization-maintaining fiber (2).
6. A temperature-tuned fiber filter according to claim 1, wherein:
the transmission vibration direction of the linear analyzer (5) is parallel to the transmission vibration direction of the linear polarizer (1).
7. A temperature-tuned fiber filter according to claim 1, wherein:
the lengths of the first high birefringence polarization-maintaining fiber (2) and the second high birefringence polarization-maintaining fiber (4) are equal, and the initial birefringence rates are both 3.6 multiplied by 10 -4 The coefficient of variation of birefringence with temperature was-1X 10 -7 /℃。
8. A temperature-tuned fiber filter according to claim 1, wherein:
the temperature-sensitive birefringent crystal (3) is cylindrical, has a radius equal to the radius of the first high-birefringence polarization-maintaining fiber (2) and the second high-birefringence polarization-maintaining fiber (4), has a length of 0.2m, is isotropic at a fixed temperature, and has a coefficient of variation of birefringence with temperature of-1 × 10 -5 /℃。
CN202210825133.7A 2022-07-14 2022-07-14 Temperature tuning optical fiber filter Pending CN115097658A (en)

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Application Number Priority Date Filing Date Title
CN202210825133.7A CN115097658A (en) 2022-07-14 2022-07-14 Temperature tuning optical fiber filter

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CN115097658A true CN115097658A (en) 2022-09-23

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