阅读说明：本技术 一种与方位角无关的偏振转化装置、实验装置及使用方法 (Azimuth-independent polarization conversion device, experimental device and using method ) 是由 吴小虎 刘睿一 崔峥 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种方位角无关的偏振转化装置、实验装置及使用方法,其中,该偏振转化装置仅由两个相对旋转角度为45°的传统二分之一波片简单构成,其中,两个二分之一波片的中心在一条直线上,且两个二分之一波片垂直于该条线。当横磁波入射时,无需调节二分之一波片光轴与入射面的方位角,横磁波透过两个相对旋转角为45°的二分之一波片便可偏振转化为横电波,实现两种线偏振之间与方位角无关的转化,且不同方位角下横电分量透射率的平均值高达0.93,该装置将有望促进传统二分之一波片的发展更新以及简化光学实验。(The invention discloses an azimuth-independent polarization conversion device, an experimental device and a using method, wherein the polarization conversion device is simply composed of two traditional half wave plates with a relative rotation angle of 45 degrees, the centers of the two half wave plates are on a straight line, and the two half wave plates are perpendicular to the line. When transverse magnetic waves are incident, the azimuth angles of the optical axis of the half wave plate and the incident plane do not need to be adjusted, the transverse magnetic waves can be polarized and converted into transverse electric waves through the two half wave plates with the relative rotation angles of 45 degrees, the conversion between the two linear polarizations and irrelevant to the azimuth angles is realized, the average value of transverse electric component transmittance under different azimuth angles is up to 0.93, and the device is expected to promote the development and updating of the traditional half wave plate and simplify an optical experiment.)

1. An azimuthally independent polarization conversion apparatus, comprising: the first half wave plate and the second half wave plate are arranged on the same straight line, the first half wave plate and the second half wave plate are perpendicular to the line, and the relative rotation angle between the first half wave plate and the second half wave plate is 45 degrees.

2. The azimuthally independent polarization conversion device of claim 1, wherein said first half-wave plate and said second half-wave plate are structurally identical.

3. The apparatus according to claim 1, wherein the first half-wave plate and the second half-wave plate are movable, and if the position of the first half-wave plate is changed, the second half-wave plate is also changed, so that the rotation angle between the two half-wave plates is 45 °, and if the position of the second half-wave plate is changed, the first half-wave plate is also changed, so that the rotation angle between the two half-wave plates is 45 °.

4. The polarization conversion device according to claim 1, wherein when a transverse magnetic wave is incident, the transverse magnetic wave is polarized and converted into a transverse electric wave through two half wave plates having a relative rotation angle of 45 ° without adjusting the azimuth angle of the optical axis of the half wave plate and the incident surface.

5. The polarization conversion device according to claim 4, wherein the azimuth angle is any one of 0 ° to 360 °, and the transverse magnetic wave and the transverse electric wave are mutually polarization-converted.

6. An experimental device for an azimuth-independent polarization conversion device, comprising: the polarization conversion device, the laser, the beam splitter, the first optical power meter, the second optical power meter, and the processor of any one of claims 1 to 5, wherein,

the laser is used for emitting transverse magnetic waves;

the polarization conversion device is arranged between the laser and the beam splitter and is used for converting the transverse magnetic wave into a transverse electric wave;

the beam splitter is used for splitting the transmitted wave of the polarization conversion device into a transverse electric wave component and a transverse magnetic wave component;

the first optical power meter and the second optical power meter are arranged behind the beam splitter, the first optical power meter is used for measuring the intensity of the transverse electric wave component, and the second optical power meter is used for measuring the intensity of the transverse magnetic wave component;

the processor is connected with the first optical power meter and the second optical power meter, and is configured to process intensities of the plurality of transverse electric wave components and intensities of the plurality of transverse magnetic wave components, obtain an average value of transverse wave component transmittances at different azimuths, and further determine whether the polarization conversion device realizes perfect polarization conversion at any azimuth angle.

7. An experimental device using method of polarization conversion device independent of azimuth angle is characterized in that, based on the experimental device of claim 6, the method comprises the following steps:

emitting transverse magnetic waves by using the laser;

enabling the transverse magnetic wave to penetrate through the polarization conversion device to obtain a transmitted wave;

splitting the transmitted wave into a transverse magnetic wave component and a transverse electric wave component via the beam splitter;

measuring the intensity of the transverse magnetic wave component and the intensity of the transverse electric wave component by using the first optical power meter and the second optical power meter respectively;

changing the azimuth angles, and measuring the intensity of the transverse magnetic wave component and the intensity of the transverse electric wave component under a plurality of azimuth angles;

and processing the intensities of the plurality of transverse electric wave components and the intensities of the transverse magnetic wave components through the processor to obtain an average value of the transverse wave component transmissivity under different azimuth angles, and further determining whether the polarization conversion device realizes perfect polarization conversion under any azimuth angle.

Technical Field

The invention relates to the technical field of electromagnetic wave polarization conversion, in particular to a polarization conversion device irrelevant to an azimuth angle, an experimental device and a using method.

Background

The polarization state is one of important characteristics of electromagnetic waves and can be classified into linear polarization, circular polarization, and the like. Different polarization states are used in different scenarios, such as object detection, satellite communication, radar immunity, etc. It is therefore of great interest to achieve a free control of the polarization.

Half-wave plates (HWPs) are a conventional polarization conversion optical device, which can effectively control the polarization state of linear polarization and the rotation direction of circular polarization. However, the present polarization control using a half-wave plate has the following two problems. First, conventional HWPs employ birefringent crystals, which cause a phase delay between two waves with orthogonal polarization states, resulting in a thickness and bandwidth limitation of the HWP. Second, due to the in-plane anisotropy of the HWP, polarization conversion is strongly azimuthal, and perfect polarization conversion can only occur when the angle between the plane of incidence of the HWP and the optical axis is 45 °. This is extremely inconvenient in practical experimental operations, not only time consuming but also possible errors in the adjustment process. A number of research efforts have shown that the problem one can be solved by means of artificially structuring metamaterials and metamaterials. For the second problem, researchers have proposed that perfect polarization conversion in all azimuth angles can be achieved by using four HWPs. For linear polarization, azimuthally independent polarization conversion between Transverse Magnetic (TM) and Transverse Electric (TE) waves has practical application in achieving polarization independent angular selectivity. However, the existing method has the problems of complex structure, strong azimuth dependence, low conversion rate and the like, and the effectiveness and the integration degree of the system are reduced in practice. Therefore, it is necessary to design a polarization conversion device with simple structure, independent azimuth angle and high conversion efficiency.

Disclosure of Invention

The invention provides a polarization conversion device irrelevant to an azimuth angle, which is used for solving the technical problems of complex structure and sensitive azimuth angle of the existing polarization conversion device.

An embodiment of an aspect of the present invention provides an azimuth-independent polarization conversion apparatus, including: the first half wave plate and the second half wave plate are arranged on the same straight line, the first half wave plate and the second half wave plate are perpendicular to the line, and the relative rotation angle between the first half wave plate and the second half wave plate is 45 degrees.

Another embodiment of the present invention provides an experimental apparatus for an azimuth-independent polarization conversion apparatus, including: the polarization conversion device, the laser, the beam splitter, the first optical power meter, the second optical power meter and the processor are arranged, wherein the laser is used for emitting transverse magnetic waves; the polarization conversion device is arranged between the laser and the beam splitter and is used for converting the transverse magnetic wave into a transverse electric wave; the beam splitter is used for splitting the transmitted wave of the polarization conversion device into a transverse electric wave component and a transverse magnetic wave component; the first optical power meter and the second optical power meter are arranged behind the beam splitter, the first optical power meter is used for measuring the intensity of the transverse wave electric component, and the second optical power meter is used for measuring the intensity of the transverse magnetic wave component; the processor is connected with the first optical power meter and the second optical power meter, and is configured to process intensities of the plurality of transverse electric wave components and intensities of the plurality of transverse magnetic wave components, obtain an average value of transverse wave component transmittances at different azimuths, and further determine whether the polarization conversion device realizes perfect polarization conversion at any azimuth angle.

In another aspect, the present invention provides a method for using an experimental device of an azimuth-independent polarization conversion device, comprising the following steps: emitting transverse magnetic waves by using the laser; enabling the transverse magnetic wave to penetrate through the polarization conversion device to obtain a transmitted wave; splitting the transmitted wave into a transverse magnetic wave component and a transverse electric wave component via the beam splitter; measuring the intensity of the transverse magnetic wave component and the intensity of the transverse electric wave component by using the first optical power meter and the second optical power meter respectively; changing the azimuth angles, and measuring the intensity of the transverse magnetic wave component and the intensity of the transverse electric wave component under a plurality of azimuth angles; and processing the intensities of the plurality of transverse electric wave components and the intensities of the transverse magnetic wave components through the processor to obtain an average value of the transmissivity of the transverse wave components at different azimuth angles, and further determining whether the polarization conversion device realizes perfect polarization conversion at any azimuth angle.

The technical scheme of the invention at least realizes the following beneficial technical effects:

the linear polarization conversion device is composed of only two traditional half wave plates which rotate 45 degrees relatively, can realize the linear polarization conversion of an omnidirectional angle, solves the problem that the included angle between the optical axis of the half wave plate and the incident plane needs to be adjusted manually in the prior art, has a simple structure, and simplifies the optical experiment.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The foregoing and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of an azimuthally independent polarization conversion apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an experimental setup for measuring transmittance of two half-wave plate HWPs in accordance with an embodiment of the present invention;

FIG. 3 is a graph of transmission through a conventional HWP as a function of azimuth in accordance with one embodiment of the present invention;

FIG. 4 is a graph of transmission versus azimuthal angle for a polarization conversion device of the present invention, according to one embodiment of the present invention.

Description of reference numerals: the device comprises a 10-azimuth-independent polarization conversion device, a 1-first half wave plate, a 2-second half wave plate, a 3-laser, a 4-beam splitter, a 5-first optical power meter and a 6-second optical power meter.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

An azimuth-independent polarization conversion device, an experimental device and a using method according to embodiments of the present invention are described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an azimuthally independent polarization conversion apparatus according to an embodiment of the present invention.

As shown in fig. 1, the apparatus 10 includes: the transverse magnetic TM wave is incident, the azimuth angle between the optical axis of the half wave plate and the incident plane does not need to be adjusted, and the transverse magnetic wave can be perfectly polarized and converted into the transverse electric TE wave through the two half wave plates with the relative rotation angles of 45 degrees.

The first half wave plate and the second half wave plate are consistent in structure, the first half wave plate and the second half wave plate can move, if the position of the first half wave plate is changed, the second half wave plate is also changed, the rotation angle between the two half wave plates is ensured to be 45 degrees, if the position of the second half wave plate is changed, the first half wave plate is also changed, and the rotation angle between the two half wave plates is ensured to be 45 degrees.

It should be noted that, the azimuth angle is any angle from 0 ° to 360 °, and the transverse magnetic wave and the transverse electric wave can be converted in polarization.

Specifically, the performance of the polarization conversion device proposed by the present invention is verified by an experimental device of the polarization conversion device independent of the azimuth angle.

As shown in fig. 2, the experimental apparatus of the polarization conversion apparatus independent of the azimuth angle includes: a first half wave plate 1 and a second half wave plate 2, a laser 3, a beam splitter 4, a first power meter 5, a second power meter 6 and a processor (not shown).

Wherein, the relative included angle between the two half wave plates is 45 degrees; the wavelength of the laser 4 is 633nm, and the power is 1.5 mW; the beam splitter 5 is for splitting the transmitted light wave (transmitted wave) into a transverse magnetic TM component and a transverse electric TE component; the first power meter 6 is used for measuring the strength of the transverse magnetic TM component; the second power meter 7 is used to measure the intensity of the transverse electric TE component.

The specific experimental process is as follows: the laser 4 emits a linear polarized wave with wavelength of 633nm and power of 1.5mW, the linear polarized wave penetrates through a first half wave plate 1 and a second half wave plate 2 with relative rotation angle of 45 degrees, the transmitted wave is divided into a transverse magnetic TM component and a transverse electric TE component through a beam splitter, then the strength of the transverse magnetic TM component and the strength of the transverse electric TE component are respectively measured by a first power meter 6 and a second power meter 7, finally, azimuth angles are changed for many times, the strength of the transverse magnetic TM component and the transverse electric TE component at different azimuth angles are measured, a processor is utilized to process the data to obtain the average value of the transverse wave component transmittance at different azimuth angles, and further, whether perfect polarization conversion is achieved at any azimuth angle is determined.

Further, the experiment first measured TE and TM component intensities through a conventional half-wave plate, as shown in fig. 3, fig. 3(a) and (b) respectively show three sets of TE and TM component transmittance experimental data, and the black solid line is the actual theoretical calculation data, and it can be seen that the experimental data is consistent with the graph based on the present. It can be seen that a complete conversion between the two polarization states is only achieved at 45 °, 135 °, 225 ° and 315 ° by means of a conventional half-wave plate, i.e. a conventional half-wave plate arrangement is very sensitive to the azimuth angle.

Further, as shown in fig. 4, when an incident wave TM wave passes through the polarization conversion device of the present invention, the difference between the maximum value and the minimum value of the transmittance of the transverse electric TE component is only 0.06, and therefore the transmittance of the transverse electric TE component is almost independent of the azimuth angle. Furthermore, as can be seen from the figure, the transmittance of the transverse electric TE component measured at different azimuth angles is as high as 0.93 on average, and the result shows that almost perfect polarization conversion can be achieved at any incidence plane. The above results thus provide strong evidence for the realization of azimuthally independent polarization conversion based on two half-wave plates HPWs with a relative rotation angle of 45 °. In the embodiment, the two devices with the relative rotation angle of 45 ° HPWs provided by the invention can realize polarization conversion at any azimuth angle, so that the problem of manually calibrating the included angle between the optical axis and the incident plane in an optical experiment can be avoided, and the efficiency of the optical experiment is further improved.

In summary, the polarization conversion device unrelated to the azimuth angle provided by the embodiment of the invention can realize the linear polarization conversion of the azimuth angle through the two traditional half wave plates which rotate 45 degrees relatively, solves the problem that the included angle between the optical axis and the incident plane of the half wave plate needs to be manually adjusted in the prior art, has a simple structure, simplifies the optical experiment, and is expected to promote the development and updating of the traditional half wave plate and simplify the optical experiment.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.