JPH10268241A - Device and method for light separation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a mechanical driving part and to reduce the influence of temperature variation on constituent elements by making it possible to separate a wavelength component by switching the angle of rotation of a plane of polarization. SOLUTION: The optical separating device is equipped with a polarization plane rotating means 2 which rotates and projects incident light L while rotating the plane of polarization at different angles by wavelength components and a wavelength component separating means 3 which separates a wavelength component L1 in a specific polarizing direction in the incident light L transmitted through the polarization plane rotating means 2, and the wavelength component L1 (L2) separated by the wavelength component separating means 3 is selected by switching the angle of rotation of the planes of polarization of the wavelength components L1 and L2. The polarization plane rotating means 2 uses an FR formed of two kinds of Faraday medium, e.g. (HoTbBi)3Fe5012 and (BiYbTb)3Fe5012. Then 1st and 2nd permanent magnets 4 and 5 are held slidably in one body to invert the direction of a magnetic field applied to a Faraday rotor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitably used for optical measurement, optical information processing, and the like, and selectively extracts one or a plurality of wavelength components from incident light having a plurality of wavelength components. The present invention relates to a light separation device and a method thereof.

[0002]

2. Description of the Related Art Conventionally, properties of light (phase, polarization, wavelength, etc.)
Attention has been paid to high-precision optical measurement using light, and a method of selectively extracting light of a predetermined wavelength from incident light including light of a plurality of wavelengths has been studied.

As an example of such a light separation method, for example, a method of selectively extracting light of a predetermined wavelength by mechanically rotating a diffraction grating or an interference filter, or a method in which a Fabry-Perot resonator detects only a resonance wavelength is used. A method of extracting light of a predetermined wavelength by mechanically changing the length of the resonator using the property of transmission, and furthermore, injecting liquid crystal or the like inside and electrically changing the refractive index of the liquid crystal or the like. In some cases, the optical path length is changed by changing the optical path length.

[0004]

However, in the method of rotating the diffraction grating or the interference filter or the method of changing the resonator length of the Fabry-Perot resonator as described above, since a mechanical Since the runnability of the operation of the driving part greatly affects the accuracy of light separation, there is a problem that the device is complicated and easily expensive.When a liquid crystal or the like is used, there is no driving part, but there is no driving part. There has been a problem that the resonance wavelength is not stable due to the temperature characteristics and the change of the gap with time.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a light separating apparatus and a method thereof which do not have a mechanical driving unit and are hardly affected by a temperature change of a component. Aim.

[0006]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above background, and the invention of claim 1 is directed to one or more wavelengths of incident light having a plurality of wavelength components. In a light separating device that selects and emits a component, a polarization plane rotation unit that rotates the polarization plane of the incident light at a different angle for each wavelength component and emits the polarization plane, and a polarization plane rotation unit that transmits through the polarization plane rotation unit A wavelength component separating unit for separating wavelength components in a predetermined polarization direction, and selecting a wavelength component separated by the wavelength component separating unit by switching a rotation angle of a polarization plane of each wavelength component in the polarization plane rotating unit. It is characterized by making it possible.

According to a second aspect of the present invention, in the first aspect, the polarization plane rotating means has a first state in which the polarization directions of at least two wavelength components are emitted with orthogonal directions, and the polarized light having an orthogonal relationship of the wavelength components. A second state in which the directions are exchanged, and the polarization plane rotating means is moved from the first state to the second state.
By switching to the state described above, the wavelength components to be separated can be selected.

According to a third aspect of the present invention, in the first aspect, the polarization directions of the two wavelength components of the incident light are parallel to each other, and the polarization plane rotating means is in the first state.
The polarization direction of one wavelength component of the incident light transmitted through the polarization plane rotating means makes an angle of 45 ° with the polarization direction of the incident light, and the polarization direction of the other wavelength component is the polarization direction of the one wavelength component. It is characterized in that the plane of polarization is rotated so as to be orthogonal to the direction.

According to a fourth aspect of the present invention, in the first to third aspects, the polarization plane rotating means includes a Faraday medium,
Magnetic field forming means for applying a magnetic field to the Faraday medium, and by changing the magnetic field applied to the Faraday medium by the magnetic field forming means, a wavelength component to be separated is selected. .

A fifth aspect of the present invention is characterized in that the polarization plane rotating means in the fourth aspect is configured by combining two or more kinds of Faraday media in series.

According to a sixth aspect of the present invention, there is provided a light separating device for selecting and outputting one or a plurality of wavelength components from incident light having a plurality of wavelength components, wherein the incident lights have polarization directions orthogonal to each other. Polarization separating means for separating the first polarized light and second polarized light, first polarization plane rotating means for rotating the plane of polarization of the first polarized light at a different angle for each wavelength component and emitting the same, The first light transmitted through the first polarization plane rotating means.
A first wavelength component separating means for separating a wavelength component of a predetermined polarization direction in the polarized light of the second direction, and a second polarization plane rotation for rotating the polarization plane of the second polarization at a different angle for each wavelength component and emitting the same. Means for separating a wavelength component of a predetermined polarization direction in the second polarized light transmitted through the second polarization plane rotating means.
Wavelength component separation means, and the wavelengths separated by the wavelength component separation means by switching the rotation angle of the polarization plane of each wavelength component in the first polarization plane rotation means and the second polarization plane rotation means. It is characterized in that components can be selected.

According to a seventh aspect of the present invention, there is provided a light separating method for selecting and outputting one or a plurality of wavelength components from incident light having a plurality of wavelength components, wherein the polarization plane of the incident light is changed for each wavelength component. By rotating at a different angle, the wavelength components in the predetermined polarization direction in the incident light are separated, and the wavelength components to be separated are selected by switching the rotation angle of the polarization plane of each wavelength component. .

According to an eighth aspect of the present invention, there is provided a light separating method for selecting and outputting one or a plurality of wavelength components from incident light having a plurality of wavelength components, wherein the incident lights have polarization directions orthogonal to each other. The first polarized light and the second polarized light are separated, and the polarization plane of the first polarized light is rotated at a different angle for each wavelength component to separate a wavelength component in a predetermined polarization direction in the first polarized light. Then, the polarization plane of the second polarized light is rotated at a different angle for each wavelength component to separate a wavelength component in a predetermined polarization direction in the second polarized light, and further, the first polarized light and the second polarized light are separated. The wavelength components to be separated are selected by switching the rotation angle of the plane of polarization of each wavelength component in polarized light.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described. FIG. 1 is a schematic diagram of a light splitting device according to a first embodiment. Reference numeral 1 denotes a light splitting device according to the present embodiment. This light splitting device 1 converts a polarization plane of incident light L into a wavelength component. A polarization plane rotation unit 2 that rotates and emits at a different angle every time, and a wavelength component separation unit 3 that separates a wavelength component L1 of a predetermined polarization direction in the incident light L transmitted through the polarization plane rotation unit 2. It is characterized in that the wavelength component L1 (L2) separated by the wavelength component separation means 3 can be selected by switching the rotation angle of the polarization plane of each wavelength component L1 and L2 in the polarization plane rotation means 2. is there.

More specifically, the polarization plane rotating means 2 includes:
For example, (HoTbBi) 3Fe having a thickness of 1216 μm
5012 and 608 μm thick (BiYbTb) 3Fe
5012 Faraday rotator (FR) composed of two types of Faraday media was used.

And, in this Faraday rotor FR,
As a magnetic field forming means for applying a magnetic field of about 14000 e which is equal to or more than a saturation magnetic field of a wavelength of 1.5 μm, a hollow cylindrical first permanent magnet 4 is arranged so as to surround the Faraday rotor FR. In the embodiment,
Second permanent magnets 4 having a polarity opposite to that of the first permanent magnets 4 are coaxially arranged at a predetermined interval.
By holding the two magnets integrally slidably, the direction of the magnetic field applied to the Faraday rotor FR is reversed. The Faraday rotor FR rotates the polarization plane of the incident light L for each wavelength component by the wavelength dispersion of the Verdet constant in a state where the above-described magnetic field is applied.

Here, the state in which a magnetic field is applied by the first permanent magnet 4 is referred to as a first state, and the state in which a magnetic field is applied by the second permanent magnet 5 is referred to as a second state. In addition, PBS (polarization beam splitter) was used as the long component separating means.

The operation of the thus-configured light separating device 1 according to the present embodiment will be described. First, the polarization plane rotating means 2 is set to the first state, and the Faraday rotor FR is supplied to the Faraday rotor FR. 1.5 μm light (L1)
And an incident light L composed of 1.3 μm light (L2) (the polarization direction of the incident light L at this time is indicated by X in FIG. 2).

The incident light L is transmitted through the Faraday rotor FR.
When the light is transmitted, the polarization directions of the wavelength components L1 and L2 are -225 ° when viewed from the optical axis direction, and the wavelength component L2 is- Each of them is rotated to 315 °, and the relative angles between the adjustments L1 and L2 are 90 °.

The two wavelength components L1 and L2, which are individually rotated so that the polarization directions are orthogonal to each other, are made incident on the wavelength component separating means 3 arranged in front of the optical axis direction. By previously setting the component separating means 3 in such a position as to transmit a wavelength component having a polarization direction of + 45 ° and reflect a wavelength component having a polarization direction of −45 °, the wavelength component L1 is reflected. By transmitting the wavelength component L2, the latter wavelength component L2 (wavelength 1.3 μm) is transmitted.
m) is selectively retrieved.

Then, the first and second permanent magnets 4 and 5 constituting the polarization plane rotating means 2 are replaced with each other. When the rotating means 2 is switched to the second state, the polarization direction of each of the wavelength components L1 and L2 in a state where the light is transmitted through the Faraday rotor FR is such that the wavelength component L1 is + 225 °, as shown in FIG. The wavelength components L2 are rotated to + 315 °, respectively, and the relative angles between the adjustments L1 and L2 are 90 °.

The two wavelength components L1 and L2, which have been individually rotated so that the polarization directions are orthogonal to each other, are made incident on the wavelength component separating means 3 disposed forward of the optical axis in the above-described manner. As shown in FIG.
Is set in advance so that it transmits the wavelength component having the polarization direction of + 45 ° and reflects the wavelength component having the polarization direction of −45 °, so that the wavelength component L1 is transmitted and the wavelength component L2 is transmitted. Is reflected, the former wavelength component L
1 (wavelength 1.5 μm) is selectively extracted.

Therefore, the wavelength to be extracted can be selected by a simple operation such as sliding the permanent magnets 4 and 5 relative to the Faraday rotor FR. Moreover, the relative displacement between the permanent magnets 4, 5 and the Faraday rotor FR has a very small effect on the change in the magnetic field applied to the Faraday rotor FR by the permanent magnets 4, 5.
Accordingly, a stable wavelength selective extraction operation appears.

FIGS. 5 and 6 are schematic diagrams of a light separating device 10 according to a second embodiment of the present invention. The light separating device 10 according to the present embodiment includes a plurality of wavelength components L1 and L2.
A light separating device that selects and emits one or a plurality of wavelength components in the incident light L having the first polarization M1 and the second polarization having the polarization directions orthogonal to each other. M2; a first polarization plane rotating unit 12 for rotating the plane of polarization of the first polarized light M1 at a different angle for each of the wavelength components L1 and L2 and emitting the same; First wavelength component separating means 13 for separating wavelength components L1 and L2 of a predetermined polarization direction in the first polarized light M1 transmitted through the polarization plane rotating means 12, and the second polarized light M2
A second polarization plane rotation means 14 for rotating the polarization plane at a different angle for each of the wavelength components L1 and L2 and emitting the same, and a predetermined polarization in the second polarized light M2 transmitted through the second polarization plane rotation means 14. And a second wavelength component separating means 15 for separating the wavelength components L1 and L2 in the polarization directions of the first and second polarization planes. By switching the rotation angle of the polarization plane, the wavelength components separated by the respective wavelength component separating means 13 and 15 can be selected.

More specifically, a rutile crystal plate is used for the polarization separating means 11, and a 1216 μm thick (HoTb) is used as the first and second polarization plane rotating means 12 and 14.
Bi) 3Fe5012 and 608 μm thick (BiYbT)
b) Faraday raw data FR composed of two types of Faraday media of 3Fe5012 was used. And
These first and second polarization plane rotation means 12 and 14 are provided integrally, and the two polarization plane rotation means 1 are provided by changing the incident position in a direction orthogonal to the optical axis.
It is made to function as 2,14. Further, the first and second wavelength component separation means 13, 15
A rutile crystal plate is used, and the first and second wavelength component separating means 13 and 15 are provided integrally. By changing the incident position in a direction orthogonal to the optical axis, two polarization components are separated. It is made to function as wavefront rotating means 13 and 15. Further, the Faraday rotor F
A hollow cylindrical first permanent magnet 16 is disposed as a magnetic field forming means for applying a magnetic field of about 14000 e, which is equal to or greater than the saturation magnetic field of 1.5 μm in wavelength, so as to surround R. , A second permanent magnet 17 having a polarity opposite to that of the first permanent magnet 4 is arranged coaxially at a predetermined interval, and these two magnets are integrally slidably held. The configuration is such that the direction of the magnetic field applied to the Faraday rotor FR is reversed. Between the Faraday rotor FR and the wavelength component separating means 13 and 15, there is provided a half-wave plate 18 for emitting the incident light with the polarization direction symmetrical with respect to the optical axis.

Next, the operation of the thus-configured light separating device 10 according to the present embodiment will be described. First, the first
8 is set in the first state in which the permanent magnet 16 is opposed to the Faraday rotor FR.
As shown in FIG. 9, an azimuth angle is set from a direction horizontal to the plane of the paper, the polarized light in the 0 ° direction is refracted, and the polarized light in the 90 ° direction is set to travel straight. In this state, when the light (L1) having a wavelength of 1.5 μm and the light (L2) having a wavelength of 1.3 μm having the same polarization direction enter the polarization separation means 11, the incident light L is converted into the polarization separation means. 11 separates the refracted polarized light M1 and the rectilinear polarized light M2.

Then, the Faraday rotor FR changes the polarization plane of the light L2 having a wavelength of 1.3 μm to about −3 due to wavelength dispersion, as shown in FIG.
Rotate by 15 ° (azimuth angle −315 ° = + 45 °) and change the plane of polarization of light L1 having a wavelength of 1.5 μm to about −225 ° (azimuth angle −45 °).
(225 ° = −45 °). Further, as shown in FIG. 11, these wavelength components are converted into polarization at azimuth + 45 ° (wavelength component L2) to 0 ° and polarization at azimuth -45 ° (wavelength component L1) is rotated so as to be + 90 °, and then is made incident on the first wavelength component separating means 13, whereby the wavelength component L1 is made to go straight and the wavelength component L2 is refracted.

As shown in FIG. 12, the Faraday rotor FR changes the plane of polarization of the light L2 having a wavelength of 1.3 μm to approximately −315 ° (azimuth angle −225 ° = −25 °) due to chromatic dispersion as shown in FIG. 45 °) to rotate the polarization plane of the light L1 having a wavelength of 1/5 μm to about −225 ° (azimuth angle −135 ° = +
45 °) Rotate. Further, these wavelength components are 1
As shown in FIG. 13, the polarization at the azimuth angle of + 45 ° (wavelength component L1) is reduced to 0 ° and the azimuth angle of −4 as shown in FIG.
After the 5 ° polarized light (wavelength component L2) is rotated to be + 90 ° and then incident on the second wavelength component separating means 15, the wavelength component L1 is refracted and the wavelength component L1 is refracted. L2 is made to go straight on.

Therefore, the wavelength component separating means (1)
In (3, 15), as shown in FIG.
The m wavelength components L1 are synthesized and emitted.

On the other hand, instead of the permanent magnet 16, another permanent magnet 17 is
In the case of the state of (1), each polarization plane rotating means 12,
The polarizations of the wavelength components L1 and L2 at 14 are opposite to each other, and the wavelength component L2 having a wavelength of 1.3 μm is synthesized and emitted by the wavelength component separating means (13, 15).

Therefore, the light separating device 1 according to the present embodiment
Even in the case of 0, as in the first embodiment described above, by simply sliding the permanent magnet, a simple and stable wavelength can be selected.

The above embodiments are merely examples, and various modifications can be made based on design requirements and the like. For example, although an example in which a permanent magnet is used to form the magnetic field has been described, an electromagnet may be used, and an example in which a wavelength of 1.3 μm and a wavelength of 1.5 μm are selected has been described. For example, HeN with wavelengths of 633 nm and 515 nm
The present invention is also applicable to the case where the e-laser light and the argon laser light are separated and selected. Further, by providing the light separating devices in a multi-stage manner, it becomes possible to separate three or more types of wavelength components. Further, an optical waveguide or an optical fiber made of a Faraday medium can be used as the polarization plane rotating means.

[0033]

As described above, according to the present invention,
The polarization directions of at least two wavelength components of the incident light are made different, and only the desired wavelength component can be separated and extracted by the wavelength component separation means, and the polarization direction of the wavelength component is changed by the polarization plane rotation means. Thereby, the extracted wavelength component in the wavelength component separating means can be changed. Therefore, it is possible to select a wavelength component without using a mechanically movable part, so that it is possible to perform a stable selection operation with a simple structure.

By using a Faraday rotator and a magnet for the polarization plane rotating means, it is possible to easily control the polarization direction by changing the intensity of the magnetic field. In addition, since only the direction of the magnetic field needs to be controlled, the influence of variations in the strength of the magnetic field is reduced as much as possible, and a stable operation is possible from this point as well.

After separating the polarization of the incident light, the light separation device having no polarization dependence can be obtained by further combining the polarization of the outgoing light. Further, a plurality of wavelength component separation means are provided. As a result, wavelengths other than the three wavelengths can be separated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a light separating device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an operation of the light separating device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a change direction of incident light.

FIG. 4 is a diagram illustrating a polarization direction by a Faraday rotor in a first state.

FIG. 5 is a diagram illustrating a polarization direction by a Faraday rotor in a second state.

FIG. 6 is a configuration diagram of a light separating device according to a second embodiment of the present invention.

FIG. 7 is an operation explanatory view of a light separating device according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating a direction of separation of incident light by polarization separation means.

FIG. 9 is a diagram illustrating a direction in which incident light is separated by polarization separation means.

FIG. 10 is a diagram illustrating a polarization direction by a Faraday rotor in a first state.

FIG. 11 is a diagram showing a change state by the half-wave plate in the first state.

FIG. 12 is a diagram illustrating a polarization direction by a Faraday rotor in a first state.

FIG. 13 is a diagram illustrating a change state by the half-wave plate in the first state.

FIG. 14 is a diagram illustrating an emission state from the wavelength component separation device in the first state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 10 ... Light separation device 2 ... Polarization plane rotation means 3 ... Wavelength component separation means 4, 16 ... First permanent magnet (magnetic field forming means) 5, 17 ... Second permanent magnet (magnetic field forming means) 11 ... Polarized light Separating means 12 ... First polarization plane rotation means 13 ... First wavelength component separation means 14 ... Second polarization plane rotation means 15 ... Second wavelength component separation means

Claims (8)

[Claims] 1. One of the incident lights having a plurality of wavelength components.
In a light separation device that selects and emits one or a plurality of wavelength components, a polarization plane rotation unit that rotates the polarization plane of the incident light at a different angle for each wavelength component and emits the light, and transmits the polarization plane rotation unit. Wavelength component separating means for separating a wavelength component in a predetermined polarization direction in the incident light, wherein the wavelength component is separated by the wavelength component separating means by switching the rotation angle of the polarization plane of each wavelength component in the polarization plane rotating means. A light separating device capable of selecting a wavelength component. 2. A first state in which the polarization plane rotating means makes the polarization directions of at least two wavelength components orthogonal and emits light, and a second state in which the polarization directions of the wavelength components orthogonal to each other are emitted and emitted. 2. The optical separation device according to claim 1, wherein a wavelength component to be separated can be selected by switching the polarization plane rotation unit from the first state to the second state. . 3. The polarization direction of the two wavelength components of the incident light is parallel to each other, and the polarization plane rotation unit is configured to detect, in the first state, one wavelength component of the incident light transmitted through the polarization plane rotation unit. Polarization direction is 4 with respect to the polarization direction of the incident light.
3. The optical separation device according to claim 2, wherein the optical separation device makes an angle of 5 [deg.] And performs polarization plane rotation such that the polarization direction of the other wavelength component is orthogonal to the polarization direction of the one wavelength component. 4. The polarization plane rotating means comprises a Faraday medium and a magnetic field forming means for applying a magnetic field to the Faraday medium. The magnetic field forming means separates the Faraday medium by changing the magnetic field applied to the Faraday medium. 4. The light separating device according to claim 1, wherein a wavelength component is selected. 5. The light separating apparatus according to claim 4, wherein said polarization plane rotating means is constituted by combining two or more kinds of Faraday media in series. 6. One of the incident lights having a plurality of wavelength components.
A light separating device that selects and emits one or a plurality of wavelength components, and a polarization separating unit that separates the incident light into a first polarized light and a second polarized light having polarization directions orthogonal to each other; First polarization plane rotation means for rotating the polarization plane of polarized light at a different angle for each wavelength component and emitting the same, and a wavelength of a predetermined polarization direction in the first polarized light transmitted through the first polarization plane rotation means First wavelength component separation means for separating components, second polarization plane rotation means for rotating the polarization plane of the second polarized light at a different angle for each wavelength component, and emitting the same, and second polarization plane rotation. Second wavelength component separating means for separating a wavelength component in a predetermined polarization direction in the second polarized light transmitted through the means, wherein each of the first polarization plane rotating means and the second polarization plane rotating means is provided. By switching the rotation angle of the polarization plane of the wavelength component Serial optical separator device being characterized in that the selectable wavelength component separated by the wavelength component separating means. 7. One of the incident lights having a plurality of wavelength components.
In the light separation method of selecting and outputting one or a plurality of wavelength components, the polarization plane of the incident light is rotated at a different angle for each wavelength component to separate a wavelength component of a predetermined polarization direction in the incident light. A light separation method for selecting a wavelength component to be separated by switching a rotation angle of a polarization plane of each of the wavelength components. 8. One of the incident lights having a plurality of wavelength components.
In the light separation method for selecting and emitting one or a plurality of wavelength components, the incident light is separated into a first polarization and a second polarization having polarization directions orthogonal to each other, and a polarization plane of the first polarization is separated. Is rotated at a different angle for each wavelength component, to separate the wavelength component of the predetermined polarization direction in the first polarization, the polarization plane of the second polarization is rotated at a different angle for each wavelength component, A wavelength component in a predetermined polarization direction in the second polarized light is separated, and a wavelength component to be separated is selected by switching a rotation angle of a polarization plane of each wavelength component in the first polarized light and the second polarized light. A light separation method, comprising: