Thermo-optic crystal depolarizer

Abstract

The utility model relates to a thermo-optic crystal depolarizer, which comprises a laser source and a plain film positioned in the light beam propagation direction of the laser source, and the plain film is formed by thermo-optic birefringent crystals sensitive to temperature; two opposite side surfaces of the flat sheet are parallel to each other and are perpendicular to the light passing surface; a heating plate is arranged on one side face of the plain film, a refrigerating plate is arranged on the other side face of the plain film, under the heat exchange effect of the heating plate and the refrigerating plate, temperature difference is formed on the two side faces of the plain film, different positions on the plain film have different phase delays, polarization states of light beams at different positions are different after passing through the plain film, and therefore depolarization is achieved. By adopting the structure, the depolarizer with a wide wavelength range can be manufactured at a very low cost; and the temperature gradient difference can be dynamically adjusted.

Description

Technical Field

[0001] This utility model relates to the field of depolarizer technology, specifically to a thermo-optical crystal depolarizer. Background Technology

[0002] Since Marius discovered the polarization of light in 1808, various polarization devices have been invented and widely used in all aspects of human life. However, in other cases, polarized light is undesirable because it easily causes measurement errors, which necessitates depolarizing the polarized light to convert it into unpolarized light.

[0003] A depolarizer is a device that converts polarized light into unpolarized light, effectively eliminating measurement errors caused by polarization and solving polarization-dependent loss problems in fiber optic communication systems and measuring instruments. Currently, the most common method for implementing depolarizers is the use of a birefringent crystal structure with double wedge angles, which is suitable for multi-wavelength depolarization. Over the past few decades, there have been no new conceptual breakthroughs in depolarizer design. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a thermo-optical crystal depolarizer.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A thermo-optical crystal depolarizer includes a laser source and a flat plate located in the direction of laser beam propagation. The flat plate is formed of a temperature-sensitive thermo-optical birefringent crystal. Two opposite sides of the flat plate are parallel to each other and perpendicular to the light-transmitting surface. A heating plate is provided on one side of the flat plate, and a cooling plate is provided on the other side of the flat plate. Under the heat exchange effect of the heating plate and the cooling plate, a temperature difference is formed on the two sides of the flat plate, resulting in different phase delays at different positions on the flat plate. The polarization states of the beam at different positions are different after passing through the flat plate, thereby achieving depolarization.

[0007] Furthermore, the flat plate consists of two pieces, with the optical axes of the two pieces forming a 45-degree angle.

[0008] Furthermore, the flat sheet is lithium niobate, lithium tantalate, yttrium vanadate, or KDP.

[0009] The present invention adopts the above technical solution and has the following beneficial effects:

[0010] This invention employs a temperature-sensitive thermo-optical crystal flat plate. By applying a temperature gradient difference to the thermo-optical crystal flat plate, the phase delay at different positions of the thermo-optical crystal becomes different, and the polarization state of the beam at different positions also becomes different after passing through the thermo-optical crystal, thereby achieving depolarization. This allows for the manufacture of a depolarizer with a wide wavelength range at a very low cost. Furthermore, the temperature gradient difference of this invention can achieve dynamic adjustment. Attached Figure Description

[0011] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0012] Figure 1 A schematic diagram illustrating phase delay using a quartz waveplate or half-waveplate is provided.

[0013] Figure 2 This is a schematic diagram of the thermo-optical crystal depolarizer of this utility model;

[0014] Figure 3 This is a schematic diagram of another embodiment of the thermo-optical crystal depolarizer of this utility model;

[0015] Figure 4 This is a schematic diagram showing two flat optical axes at a 45-degree angle. Detailed Implementation

[0016] like Figure 1 As shown, taking a quartz half-wave plate as an example, at room temperature, the light beam is linearly polarized at position A, and at position B, the phase is delayed compared to position A, with the polarization state rotated by 90 degrees. After heating the quartz half-wave plate to a certain temperature, the phase delay of the quartz half-wave plate exceeds the half-wave plate state, and the polarized light will no longer be rotated by 90 degrees.

[0017] By replacing the quartz waveplate with a temperature-sensitive thermo-optical crystal and applying a temperature gradient to it, the phase delay varies at different positions within the crystal. Consequently, the polarization state of the beam at different positions also differs after passing through the crystal, thus achieving depolarization. Specifically, for example... Figure 2 As shown, this utility model discloses a thermo-optical crystal depolarizer, comprising a laser source 1 and a flat plate 2 located in the beam propagation direction of the laser source 1. The flat plate 2 is formed of a temperature-sensitive thermo-optical birefringent crystal, wherein the birefringent crystal can be lithium niobate, lithium tantalate, yttrium vanadate, or KDP, etc. The two opposite sides of the flat plate 2 are parallel to each other and perpendicular to the light-transmitting surface; a heating plate 3 is provided on one side of the flat plate 2, and a cooling plate 4 is provided on the other side of the flat plate 2. Under the heat exchange effect of the heating plate 3 and the cooling plate 4, a temperature difference is formed on the two sides of the flat plate 2, resulting in different phase delays at different positions on the flat plate 2. The polarization states of the beam at different positions are different after passing through the flat plate 2, thereby achieving depolarization.

[0018] The temperatures of heating plate 3 and cooling plate 4 can be set according to the actual needs of deflection.

[0019] The working principle of this invention is as follows: This invention uses a temperature-sensitive thermo-optical crystal to form a flat plate 2, which has a large thermo-optical coefficient. A heating plate 3 is placed on one side of the flat plate 2, with a temperature reaching several hundred degrees Celsius, such as 300 degrees Celsius. A cooling plate 4 is placed on the opposite side, with a temperature reduced to below 0 degrees Celsius, such as -10 degrees Celsius. The temperature difference between the two sides of the flat plate can exceed 300 degrees Celsius. The refractive index changes at different locations, resulting in different phase delays of the light beam before and after passing through the flat plate 2, leading to depolarization.

[0020] like Figure 3-4 As shown, in order to increase the depolarization performance, a two-stage structure can be set up, that is, the flat plate 2 is designed as two pieces, and the optical axes of the two flat plates 2 are at a 45-degree angle.

[0021] The specific embodiments of this utility model have been described above. However, those skilled in the art should understand that this is only an example. Those skilled in the art can make various changes or modifications to this embodiment without departing from the principle and essence of this utility model, but all such changes and modifications fall within the protection scope of this utility model.

Claims

1. A thermo-optical crystal depolarizer, characterized in that: The device includes a laser source and a flat plate located in the direction of laser beam propagation. The flat plate is formed from a temperature-sensitive thermo-optical birefringent crystal. The two opposite sides of the flat plate are parallel to each other and perpendicular to the light-transmitting surface. A heating plate is provided on one side of the flat plate, and a cooling plate is provided on the other side of the flat plate. Under the heat exchange effect of the heating plate and the cooling plate, a temperature difference is formed on the two sides of the flat plate, which causes different phase delays at different positions on the flat plate. The polarization states of the beam at different positions are different after passing through the flat plate, thereby achieving depolarization.

2. The thermo-optical crystal depolarizer according to claim 1, characterized in that: The flat plate consists of two pieces, and the optical axes of the two flat plates are at a 45-degree angle.

3. The thermo-optical crystal depolarizer according to claim 1, characterized in that: The flat sheet is lithium niobate, lithium tantalate, yttrium vanadate, or KDP.

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