CN201307189Y - Device for realizing conversion from linearly polarized light into radially polarized light - Google Patents

Abstract

The utility model belongs to the technical field of applied optics, and relates to a device for realizing the conversion from linearly polarized light into radially polarized light. A whole set of devices comprise a half-wave plate, a quarter wave plate, a birefringent crystal, a second half-wave plate and a quartz polarization rotator, which are arranged in sequence in the light direction of a light source generating linearly polarized light; an angle of 45 degrees is formed by the direction of an optical axis of the birefringent crystal and the propagation direction of laser, the right half part of the emergent light of the birefringent crystal is rotated through the second half-wave plate so as to ensure that the phase difference of the left lobe and the right lobe of light beams is 180 degrees, and the polarization state of the whole light beam rotates for 45 degrees through the quartz polarizing rotator, which forms light beams distributed in a polarization state in the radial direction. The device has the characteristics of reasonable structural design, few components, high stability, convenient use, and the like.

Description

A device for converting linearly polarized light into radially polarized light

Technical field:

The utility model belongs to the technical field of applied optics and relates to a generating device for radially polarized light. It is mainly used in particle capture, optical micromanipulation, optical information storage, light-matter interaction, microscopic system, lithography, laser processing, optical tweezers technology, super-resolution and other fields.

Background technique:

In the research on the polarization state of the beam, it is found that the polarization state is not limited to our common linear polarization, circular polarization, and elliptical polarization, but also radial polarization state and azimuth polarization state. Radially polarized light has attracted much attention due to the symmetry of the vibration direction of its electric vector with respect to the optical axis and the fact that the light intensity on the axis is always zero. Radially polarized light plays an important role in microscopy, lithography, frequency shifting, electron acceleration, optical trapping and control, material processing, and high-resolution measurement. Due to the wide application prospects of radially polarized light, researchers have proposed many implementation schemes, including placing special optical elements in the resonant cavity to generate radially polarized light, and using segmented half-wave plates. Both methods have certain limitations, the former will cause additional intracavity losses and may make laser optimization design difficult. The latter has low output power and can only obtain approximate radially polarized light. While variable helix retarders can increase the intensity of laser power, their helix profile requires specialized manufacturing techniques. Recently, someone used a Mach-Zehnder-like interferometer device to coherently superimpose a horizontally polarized TEM10 and a vertically polarized TEM10 Hermitian-Gaussian beam to obtain a radially polarized beam. Although this technique of radially polarized light has some advantages, there are still some disadvantages:

1) This method has high requirements on the stability of the interferometer, which may limit its practicability.

2) This method requires special optical design and special optical elements, such as spiral phase plate and binary diffractive optical element. This will certainly affect its wide application.

Utility model content

The problem to be solved by the utility model is to overcome the deficiencies of the above-mentioned prior art and provide a simple and stable device for converting linearly polarized light into radially polarized light. It has the characteristics of reasonable structure design, few parts, high mechanical stability and convenient use in practical application.

The basic idea of the utility model is:

The utility model provides a simple and stable device for converting linearly polarized light into radially polarized light. The whole device consists of a half-wave plate, a quarter-wave plate, a birefringent crystal, a second half-wave plate, and a quartz polarization rotator arranged in sequence along the light direction of the light source that produces linearly polarized light; the optical axis of the birefringent crystal The direction is 45° to the direction of laser propagation, and the second half-wave plate rotates the right half of the birefringent crystal outgoing light to ensure that the phase difference between the left and right lobes of the beam is 180 degrees, and the quartz polarization rotator rotates the polarization state of the entire beam 45 degrees to form a radially distributed beam of polarization.

The technical solution of the present utility model is as follows:

A device for converting linearly polarized light into radially polarized light, the whole device consists of a half-wave plate (2) and a quarter-wave plate (3) sequentially arranged along the light direction of the light source (1) generating linearly polarized light , a birefringent crystal (4), a half-wave plate (5), and a quartz polarization rotator (6); the optical axis direction of the birefringent crystal (4) is 45° to the laser propagation direction, and the half-wave plate (5) is The right half of the outgoing light from the birefringent crystal is rotated to ensure that the phase difference between the left and right lobes of the light beam is 180 degrees, and the quartz polarization rotator (6) rotates the polarization state of the entire light beam by 45 degrees.

In the above device for converting linearly polarized light into radially polarized light, the direction of the optical axis of the birefringent crystal (4) is 45 degrees to the direction of propagation of the laser light.

The above-mentioned device for converting linearly polarized light into radially polarized light rotates the polarization state of the entire light beam by 45 degrees.

A device for converting linearly polarized light into radially polarized light provided by the utility model has the structure described above. The polarized light is then divided into two beams of equal power by a birefringent crystal whose optical axis is 45 degrees to the direction of laser propagation. The degree of separation of the two beams depends on the length of the crystal. The two polarized beams are mutually orthogonal and are controlled to be in phase by a birefringent crystal with tilted optical axes. Then through the second half-wave plate, the second half-wave plate only deflects the polarization direction of the right half of the beam by 90 degrees, and the polarization direction of the left half of the light remains unchanged, and finally rotates the polarization state of all beams through a quartz polarization rotator 45 degrees, forming radially polarized light.

Compared with the prior art, the utility model has the following advantages:

1) The realization device has simple structure, convenient operation and convenient application.

2) The device has high stability and does not require other special optical components.

Description of drawings

Fig. 1 is the system structure schematic diagram of the utility model embodiment

Fig. 2 is the schematic diagram of polarization state conversion of the utility model embodiment

Detailed ways

Below in conjunction with accompanying drawing description, the embodiment of the utility model is further described in detail, but the embodiment is not only used to limit the utility model, any similar structures and similar changes of the utility model should be included in the utility model protected range.

An embodiment of the utility model provides a device for converting linearly polarized light into radially polarized light. FIG. 1 is a schematic diagram of an embodiment of the utility model. A half-wave plate (2), a quarter-wave plate (3), a birefringent crystal (4), a half-wave plate (5), and a quartz polarization rotator are sequentially arranged along the light direction of the light source (1) generating linearly polarized light (6); the optical axis direction of the birefringent crystal (4) is 45° with the laser propagation direction, and the half-wave plate (5) rotates the right half of the birefringent crystal outgoing light to ensure the left and right lobe phase difference of the light beam At 180 degrees, the quartz polarization rotator rotates the polarization state of the entire beam by 45 degrees. The laser light source outputs a linearly polarized elliptical Gaussian beam, which is converted into circularly polarized light by a half-wave plate and a quarter-wave plate, and then divided into two beams of circularly polarized light of equal power by a birefringent crystal at a angle of 45° between the optical axis direction and the laser propagation direction. , the degree of separation of the two beams depends on the length of the crystal. The two polarized beams are mutually orthogonal, and they are controlled to be in phase by a birefringent crystal with tilted optical axes. Then through the second half-wave plate, the second half-wave plate only deflects the polarization direction of the right half of the beam by 90 degrees, and the polarization direction of the left half of the light remains unchanged, and finally rotates the polarization state of all beams through a quartz polarization rotator 45 degrees, forming radially polarized light.

Fig. 2 is a schematic diagram of beam polarization distribution transformation that realizes the conversion of linearly polarized light into radially polarized light in this embodiment. This system can convert linearly polarized light beams into radially polarized light beams, and has the advantages of convenient adjustment of the beam polarization state. , successfully converted linearly polarized light into radially polarized light.

Claims (2)

1. A device for converting linearly polarized light into radially polarized light is characterized in that: a half-wave plate (2), a quarter-wave plate ( 3), birefringent crystal (4), half-wave plate (5), quartz polarization rotator (6); the optical axis direction of the birefringent crystal (4) is 45 ^° to the laser propagation direction, and the half-wave plate (5) is a pair The right half of the outgoing light from the birefringent crystal is rotated to ensure that the phase difference between the left and right lobes of the beam is 180 degrees, and the quartz polarization rotator rotates the polarization state of the entire beam by 45 degrees. 2. A device for converting linearly polarized light into radially polarized light according to claim 1, characterized in that: the half-wave plate (5) is placed on the right half of the cross-section of the propagation direction of the light source.

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