Optical adjustment device and light source generation system

Abstract

This invention provides an optical adjustment device, including an optical platform and a light source generator, three mirrors, and a collimator, which are sequentially fixed to the optical platform along the optical path. Each mirror includes a mirror body and a lens. A groove is formed from top to bottom on the upper part of the mirror body, dividing the upper part of the mirror body into a front side and a rear side. The lens is disposed on the front side of the mirror, and the bottom end of the front side is connected to the rear side. By adjusting the position of the front side of the mirror relative to the rear side, the pitch angle of the optical path can be adjusted. This invention also proposes a light source generation system based on the above-mentioned optical adjustment device. This invention adjusts the laser beam's deflection and pitch angle through the cooperation of the mirrors, allowing the beam to be transmitted to the center of the collimator, effectively reducing the collimator adjustment dimension. Simultaneously, it relies on external force to drive the elastic deformation of the mirror structure for adjustment. The structure is simple, the operation is convenient, and the optical path can remain stable for a long time after adjustment.

Description

Technical Field

[0001] This invention belongs to the field of optical adjustment technology, and specifically relates to an optical adjustment device and a light source generation system. Background Technology

[0002] Existing methods for preparing quantum entangled sources typically use a light source to generate pump light, which then passes through a BBO crystal to produce down-converted entangled photons. In the optical path, the collimating laser diode and fiber coupler have a so-called pointing angle, meaning there is an angular difference between the propagation direction of the light emitted from the light source and the normal to the collimator's front face. Current methods for adjusting parallelism usually involve repeatedly adjusting the light using an autocollimator, which is expensive, cumbersome, and time-consuming to calibrate. Chinese patent application CN115145020A discloses an optical adjustment device and method for aligning the laser propagation direction with the optical platform. The proposed reflection device consists of an optical adjustment frame and a mirror. The mirror is fixed to the top of the optical adjustment frame, and the mirror is adjusted by changing the height and deflection angle of the frame, thereby adjusting the optical path. The optical adjustment frame includes a base, a lifting structure, and an angle adjustment structure. The base has a lifting structure, the lifting structure has an angle adjustment structure, and the angle adjustment structure has the required adjustment components. The lifting structure is used to adjust the height of the angle adjustment structure and the required adjustment components. The angle adjustment structure is used to adjust the deflection angle of the required adjustment components. The lifting structure includes an inner tube, an outer tube, a gear and rack structure, and a knob. The outer tube is fitted onto the inner tube. The gear and rack structure is located between the inner and outer tubes. One side of the rack is connected to the inner tube, and the other side of the rack is connected to a gear. The knob is located on the outer wall of the outer tube and is connected to the gear. Rotating the knob drives the gear to rotate, thereby raising and lowering the rack and the inner tube.

[0003] In summary, the existing technology has the following drawbacks:

[0004] 1. Existing optical adjustment frames use a rack and pinion structure to adjust the height. The structure has many complex components and requires high machining accuracy. Poor accuracy of any one component will make it difficult to adjust the entire optical path. Moreover, since the reflector and angle adjustment structure are fixed on the lifting structure, the force of the lifting structure is mainly concentrated on the rack and pinion. Under the action of gravity for a long time, the rack and pinion will slide relative to each other, making it difficult to maintain the stability of the optical path.

[0005] 2. Existing methods for adjusting parallelism typically involve repeatedly adjusting the light using an autocollimator, which is cumbersome and time-consuming to calibrate. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to reduce the processing accuracy requirements of optical adjustment devices and maintain optical path stability over a long period of time.

[0007] The present invention solves the above-mentioned technical problems through the following technical means: an optical adjustment device, including an optical platform (7) and a light source generating device (8), a first reflector (1), a second reflector (3), a third reflector (4), and a collimator (6) fixed sequentially on the optical platform (7) along the optical path. The first reflector (1), the second reflector (3), and the third reflector (4) have the same structure, including a reflector body (a) and a lens (b) respectively. The upper part of the reflector body (a) is provided with a groove (a5) from top to bottom. The groove (a5) divides the upper part of the reflector body (a) into a front side (111) and a rear side (112) of the reflector. The lens (b) is set on the front side (111) of the reflector. The bottom end of the front side (111) of the reflector is connected to the rear side (112) of the reflector. By adjusting the position of the front side (111) of the reflector relative to the rear side (112) of the reflector, the pitch angle of the optical path can be adjusted.

[0008] As a further optimized technical solution, the lower part of the reflector body (a) is a base, and at least one first arc-shaped U-shaped hole (a1) is opened in the base along the circumference. The first reflector (1), the second reflector (3), and the third reflector (4) are fixed on the optical platform (7) by bolts passing through the corresponding first arc-shaped U-shaped hole (a1).

[0009] As a further optimized technical solution, the collimator (6) is fixed on the collimator base (5). Several second arc-shaped U-shaped holes (52) with the same arc are opened on the collimator base (5) along the circumference. The center arc of all the second arc-shaped U-shaped holes (52) is on the same circumference. The bolt passes through the second arc-shaped U-shaped holes (52) to fix the collimator base (5) on the optical platform (7).

[0010] As a further optimized technical solution, the curvature of each arc-shaped U-shaped hole is the same, the center arc of all the first arc-shaped U-shaped holes (a1) is on the same circumference, and the arc-shaped U-shaped holes are evenly distributed. The center arc of all the second arc-shaped U-shaped holes (52) is on the same circumference, and the arc-shaped U-shaped holes are evenly distributed.

[0011] As a further optimized technical solution, a lens hole (a2) is provided in the middle of the reflector body (a), and the lens (b) is glued to the lens hole (a2) of the reflector body (a).

[0012] As a further optimized technical solution, the centers of all the reflectors, light source generators (8) and collimators (6) are on the same horizontal plane.

[0013] As a further optimized technical solution, the upper sides of the front side (111) of the reflector are provided with a first through hole (a3) ​​and a third through hole (a8), and a second threaded hole (a6) is provided in the middle. The rear side (112) of the reflector is provided with a first threaded hole (a4) and a third threaded hole (a7) corresponding to the positions of the first through hole (a3) ​​and the third through hole (a8). The first bolt (c) can pass through the first through hole (a3) ​​and be screwed into the first threaded hole (a4). The third bolt (e) can pass through the third through hole (a8) and be screwed into the third threaded hole (a7). The second bolt (d) can be screwed into the second threaded hole (a6) and its rear end abuts against the rear side (112) of the reflector.

[0014] As a further optimized technical solution, the pitch angle adjustment method of the optical path is divided into two cases:

[0015] The first method involves passing the first bolt (c) through the first through hole (a3) ​​and fixing it in the first threaded hole (a4), and passing the third bolt (e) through the through hole (a8) and fixing it in the third threaded hole (a7). When both bolts are tightened simultaneously, the compression groove (a5), i.e. the front side (111) of the reflector, moves closer to the rear side (112) of the reflector, thereby causing the front side (111) of the reflector to tilt backward, thus adjusting the upward refraction of the light path and adjusting the elevation angle of the light path. If only the first bolt (c) is tightened, the light path is adjusted to the upper left; if only the third bolt (e) is tightened, the light path is adjusted to the upper right.

[0016] The second method: After passing the second bolt (d) through the second threaded hole (a6), it is placed against the rear side (112) of the reflector. By tightening the second bolt (d), the tension groove (a5) is opened, which causes the front side (111) of the reflector to move away from the rear side (112) of the reflector, thereby tilting the front side (111) of the reflector forward and adjusting the downward refraction of the light path, which is the adjustment of the downward angle of the light path. After tightening the second bolt (d) that passes through the second threaded hole (a6), the first bolt (c) fixed at the first threaded hole (a4) is tightened, causing the front side (111) of the reflector to tilt backward in the upper left direction, thereby adjusting the refraction of the light path to the lower left. After tightening the second bolt (d) that passes through the second threaded hole (a6), the third bolt (e) fixed at the third threaded hole (a7) is tightened, causing the front side (111) of the reflector to tilt backward in the upper right direction, thereby adjusting the refraction of the light path to the lower right.

[0017] As a further optimized technical solution, the specific steps for adjusting the laser beam using this optical adjustment device are as follows:

[0018] Step 1: The light source generating device (8) emits a laser beam. By coarsely adjusting the relative fixed position of the first reflector (1), the second reflector (3), and the third reflector (4) with the optical platform (7) and the pitch angle of the optical path, the laser beam is irradiated in a 2mm-3mm area near the center point of the lens (b) of the first reflector (1), the second reflector (3), and the third reflector (4).

[0019] Step 2: By adjusting the relative fixed position of the first reflector (1) and the optical platform (7), the turning angle of the laser beam reflection is adjusted so that the laser beam generated by the light source generating device (8) irradiates the center position of the lens b of the first reflector (1), and the laser beam reflected by the first reflector (1) can irradiate the center of the lens (b) of the second reflector (3).

[0020] Step 3: By adjusting the relative fixed position of the first reflector (1) and the optical platform (7), and by adjusting the first bolt (c), the second bolt (d) and the third bolt (e) of the first reflector (1), the laser beam reflected by the first reflector (1) can illuminate the center of the lens (b) of the second reflector (3), and the laser beam reflected by the second reflector (3) can illuminate the center of the lens (b) of the third reflector (4).

[0021] Specifically, (1) when the laser beam, after being reflected by the first reflector (1), does not pass through the center of the lens (b) of the second reflector (3) and instead irradiates the lower right of the center of the lens (b) of the second reflector (3), the direction of laser beam reflection is adjusted by tightening the third bolt (e) of the first reflector (1) so that it ultimately irradiates the center of the lens (b) of the second reflector (3); (2) similarly, if the laser beam irradiates the lower left of the center of the lens (b) of the second reflector (3), the direction of laser beam reflection is adjusted by tightening the first bolt (c) of the first reflector (1) so that it ultimately irradiates the center of the lens (b) of the second reflector (3); (3) if the laser beam irradiates the upper right of the center of the lens (b) of the second reflector (3), the direction of laser beam reflection is adjusted by first tightening the second bolt (d) of the first reflector (1) and then tightening the third bolt (e) of the first reflector (1) so that it ultimately irradiates the center of the lens (b) of the second reflector (3). (3) Center of lens (b) of reflector (3); (4) If the laser beam is irradiated to the upper left of the center of lens (b) of the second reflector (3), the laser beam reflection direction is adjusted by first tightening the second bolt (d) of the first reflector (1) and then tightening the first bolt (c) so that it finally irradiates the center of lens (b) of the second reflector (3); (5) If the laser beam is directly above the lens (b) of the second reflector (3), the laser beam reflection direction is adjusted by tightening the second bolt (d) of the first reflector (1) so that it finally irradiates the center of lens (b) of the second reflector (3); (6) If the laser beam is directly below the lens (b) of the second reflector (3), the laser beam reflection direction is adjusted by simultaneously tightening the first bolt (c) and the third bolt (e) of the first reflector (1) so that it finally irradiates the center of lens (b) of the second reflector (3); In the above, the pitch angle of the optical path is adjusted.

[0022] Step 4: If the laser beam reflected by the second reflector (3) does not irradiate the center of the lens (b) of the third reflector (4), adjust the second reflector (3) according to the method in step 3 so that the laser beam irradiates the center of the lens (b) of the third reflector (4).

[0023] Step 5: Set a collimator (6) in the direction of the laser beam reflected by the third reflecting mirror (4). When the laser beam does not pass through the center of the collimator (6), adjust the relative position of the collimator (6) and the optical platform (7) to achieve the translation adjustment of the optical path so that the laser beam passes through the center of the collimator (6). If the reflected laser beam irradiates above and below the center of the collimator (6), adjust the third reflecting mirror (4) according to the method in step 3 so that the laser beam passes through the center of the collimator (6), and then adjust the relative position of the collimator (6) and the optical platform (7) to achieve the translation adjustment of the optical path.

[0024] The present invention also provides a light source generating system, comprising a light source generating device (8), a first reflector (1), a convex lens (11), a second reflector (3), a first BBO crystal (15), and a half-wave plate (16) arranged sequentially along an optical path (2). After passing through the first BBO crystal (15), the light source is divided into two branch optical paths. The two branch optical paths pass through the half-wave plate (16) simultaneously. The first branch optical path includes a third reflector (4-1), a second BBO crystal (17-1), a first polarizer (18-1), a first filter (12-1), and a first collimator (6-1) arranged sequentially along the optical path (2). The second branch optical path includes a fourth reflector (4-2), a third BBO crystal (17-2), and a second polarizer (6-1) arranged sequentially along the optical path (2). The optical path (2) consists of a first reflector (1), a second filter (12-2), and a second collimator (6-2). The first reflector (1), the second reflector (3), the third reflector (4-1), and the fourth reflector (4-2) have the same structure, including a reflector body (a) and a lens (b). The upper part of the reflector body (a) has a groove (a5) from top to bottom. The groove (a5) divides the upper part of the reflector body (a) into a front side (111) and a rear side (112). The lens (b) is set on the front side (111). The bottom end of the front side (111) is connected to the rear side (112). By adjusting the position of the front side (111) relative to the rear side (112), the pitch angle of the optical path (2) can be adjusted.

[0025] As a further optimized technical solution, the working process of the light source generation system is as follows: The light source generating device (8) emits pump light, which is reflected by the first reflector (1), focused by the convex lens (11), and then incident on the first BBO crystal (15) after the transmission path is changed by the second reflector (3). The second reflector (3) is adjusted so that the light beam can illuminate the center of the first BBO crystal (15). After passing through the first BBO crystal (15), the light beam is split into a pair of entangled photons, which are polarized and rotated by the half-wave plate (16) and then enter the third reflector (4-1) and the fourth reflector (4-2) respectively. 2) After reflection and optical path angle adjustment, the two entangled photons are respectively irradiated by the centers of the second BBO crystal (17-1) and the third BBO crystal (17-2). After passing through the first polarizer (18-1) and the second polarizer (18-2), they are filtered by the first filter (12-1) and the second filter (12-2) to remove pump light and external stray light. Finally, the two entangled photons are coupled from spatial light to the optical fiber by the first collimator (6-1) and the second collimator (6-2) to prepare entangled photon pairs. The first polarizer (18-1) and the second polarizer (18-2) are polarization basis vector measurement devices used to measure the entangled state of the two entangled photons.

[0026] As a further optimized technical solution, the light source generating system further includes a set of polarizers: a third polarizer (14-1) and a fourth polarizer (14-2), which are respectively disposed between the second BBO crystal (17-1) and the first polarizer (18-1) and between the third BBO crystal (17-2) and the second polarizer (18-2).

[0027] At this time, the working process of the light source generation system is as follows: The light source generating device (8) emits pump light, which is reflected by the first reflector (1), focused by the convex lens (11), and then incident on the first BBO crystal (15) after the transmission path is changed by the second reflector (3). The second reflector (3) is adjusted so that the light beam can illuminate the center of the first BBO crystal (15). After passing through the first BBO crystal (15), the light beam is split into a pair of entangled photons. After being polarized and rotated by the half-wave plate (16), they enter the third reflector (4-1) and the fourth reflector (4-2) respectively. After being reflected by the third reflector (4-1) and the fourth reflector (4-2) respectively and the light path angle is adjusted, the two entangled photons illuminate the centers of the second BBO crystal (17-1) and the third BBO crystal (17-2) respectively. After passing through the third polarizer (14-1) and the fourth reflector (4-2) respectively, the two entangled photons illuminate the centers of the second BBO crystal (17-1) and the third BBO crystal (17-2) respectively. After passing through the first polarizer (18-1) and the fourth polarizer (14-2), the light then passes through the first polarizer (12-1) and the second polarizer (12-2) to filter out the pump light and stray light from the outside. Finally, the two entangled photons are coupled from the spatial light to the optical fiber through the first collimator (6-1) and the second collimator (6-2). The third polarizer (14-1) and the fourth polarizer (14-2) are rotated to 0° and 90° respectively, so that one entangled photon is in the H polarization state and the other entangled photon is in the V polarization state. At this time, the |HV> photon pair is prepared. The prepared |HV> photon pair is a separable state, representing a classical light source. The first polarizer (18-1) and the second polarizer (18-2) are polarization basis vector measurement devices used to measure the polarization state of the two classical light sources.

[0028] As a further optimized technical solution, the first BBO crystal (15) is a 2mm BBO crystal, the second BBO crystal (17-1) and the third BBO crystal (17-2) are BBO crystals with a thickness of 1mm, the convex lens (11) has a focal length of 200mm, the optical path distance between the convex lens (11) and the first BBO crystal (15) is 200mm, and the optical path distance between the first BBO crystal (15) and the third reflector (4-1) and the fourth reflector (4-2) is 200mm.

[0029] As a further optimized technical solution, the light source generation system also includes a coincidence counter (13) and a host computer (22). The first collimator (6-1) and the second collimator (6-2) couple two entangled photons from spatial light to optical fiber and transmit them to the coincidence counter (13). The coincidence counter (13) uses the first single-photon detector (19) and the second single-photon detector (20) to detect the two entangled photons or the two classical light sources respectively, and after performing coincidence count measurement, reports the data to the host computer (22). The host computer (22) plots the histogram of coincidence counts of entangled photon pairs or classical light sources under different polarization measurement basis vectors based on the coincidence count value.

[0030] The advantages of this invention are:

[0031] 1. The optical adjustment device proposed in this invention places multiple mirrors between the light source generator and the collimator. The laser beam deflection and pitch angles are adjusted by the cooperation between the mirrors, so that the beam is transmitted to the center of the collimator. This effectively reduces the collimator adjustment dimension and shortens the calibration time. At the same time, the adjustment is achieved by the elastic deformation of the mirror structure itself driven by bolts. The structure is simple and easy to operate. After the optical path adjustment is completed, the optical path can remain stable for a long time.

[0032] 2. This invention allows for multi-dimensional adjustment of the optical path, including rotation, pitch, and translation. The rotation angle of the optical path is adjusted through the arc-shaped U-shaped hole at the bottom of the reflector; the pitch of the optical path is adjusted through the three bolts on the upper part of the reflector; and the translation of the optical path is adjusted through the arc-shaped U-shaped hole on the collimator base. The structure is simple and the operation is convenient.

[0033] 3. In the design of the reflector structure, the lens is glued to the reflector body. The reflector body has a groove. The first and third bolts pass through the groove and are screwed from the front side of the reflector to the rear side of the reflector. The second bolt passes through the groove and rests against the rear side of the reflector from the front side of the reflector. The elevation angle of the light path is adjusted by tightening the first and third bolts, and the depression angle of the light path is adjusted by tightening the second bolt.

[0034] 4. Based on the optical adjustment device, design a light source generation system that allows the preparation of classical photon pairs and entangled photon pairs in the same optical path by switching devices, and collects coincidence counts. The characteristics of entangled photons and classical photons are displayed in the form of histograms. At the same time, it can be used to verify the reliability and authenticity of the system in preparing quantum entangled light sources. It has the flexibility to meet different experimental needs. This system can also be used as a single photon source generation device for extended experimental systems related to single photons. Attached Figure Description

[0035] Figure 1 This is an overall structural layout diagram of an optical adjustment device according to Embodiment 1 of the present invention;

[0036] Figure 2 This is a schematic diagram of the collimator fixing in Embodiment 1 of the present invention;

[0037] Figure 3 This is a structural diagram of the main body of the reflector in Embodiment 1 of the present invention;

[0038] Figure 4 This is a perspective view of the reflector in Embodiment 1 of the present invention;

[0039] Figure 5 This is a schematic diagram of the component layout of the light source generating system in Embodiment 2 of the present invention;

[0040] Figure 6 This is a schematic diagram of the component layout of another light source generating system in Embodiment 2 of the present invention;

[0041] Figure 7 This is the coincidence count histogram under different polarization measurement basis vectors in Embodiment 2 of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] like Figure 1 As shown, the optical adjustment device proposed in this invention includes an optical platform 7, a light source generating device 8, a light source generating device base 9, a first reflecting mirror 1, a second reflecting mirror 3, a third reflecting mirror 4, a collimator 6, and a collimator base 5. The first reflecting mirror 1, the second reflecting mirror 3, and the third reflecting mirror 4 have the same structure.

[0045] The light source generating device 8 is fixed to the optical platform 7 by bolts passing through the base 9 of the light source generating device. The first reflector 1, the second reflector 3, and the third reflector 4 are fixed to the optical platform 7 by bolts. (See reference) Figure 2 The collimator 6 is fixed to the collimator base 5 by bolts 10, and the collimator base 5 is fixed to the optical platform 7 by bolts. After the laser beam is emitted by the light source generator 8, it is reflected in sequence by the first reflector 1, the second reflector 3, and the third reflector 4, and coupled from the center of the collimator 6 into the optical fiber for subsequent detection.

[0046] Taking the first reflecting mirror 1 as an example, Figure 4As shown, the first reflector 1 includes a reflector body a and a lens b. The structure of the reflector body a is as follows: Figure 3 As shown, the lower part of the reflector body a is a base. Optionally, the reflector body a can be machined by CNC (numerical control) or integrally formed, or the base can be fixed separately from other parts of the reflector body a. At least one arc-shaped U-shaped hole a1 is formed along the circumference of the base to fix the upper part of the reflector body a and adjust the refraction angle of the entire optical path. In this embodiment, there are four arc-shaped U-shaped holes a1, all with the same curvature, their central arcs on the same circumference, and evenly distributed. Bolts pass through the corresponding arc-shaped U-shaped holes a1 and are screwed into the screw holes on the optical platform 7. By slightly rotating the reflector body a, the base at the lower part of the reflector body a can move along the bolts, thereby adjusting the refraction angle of the optical path. Of course, the number of arc-shaped U-shaped holes a1 can also be two, three, or more, as long as the refraction angle of the optical path can be adjusted. The reflector body a has a lens hole a2 in the middle for mounting a lens b. In this embodiment, the lens b is glued to the lens hole a2 of the reflector body a. A groove a5 is formed from top to bottom on the upper part of the reflector body a, dividing the upper part of the reflector body a into a front reflector side 111 and a rear reflector side 112. The lens b is mounted on the front reflector side 111, and the bottom end of the front reflector side 111 is connected to the rear reflector side 112, allowing the front reflector side 111 to elastically deform relative to the rear reflector side 112 under external force. As an optional material for the reflector body a, it can be made of aluminum alloy A6061 or stainless steel SUS304, or other commonly used industrial metals, as long as the front reflector side 111 can elastically deform relative to the rear reflector side 112.

[0047] The front side 111 of the reflector has a first through hole a3 and a third through hole a8 on both sides of the upper part, and a second threaded hole a6 in the middle. The rear side 112 of the reflector has a first threaded hole a4 and a third threaded hole a7 at the positions corresponding to the first through hole a3 and the third through hole a8. The first bolt c passes through the first through hole a3 and is screwed into the first threaded hole a4. The third bolt e passes through the third through hole a8 and is screwed into the third threaded hole a7. The second bolt d is screwed into the second threaded hole a6 and its rear end abuts against the rear side 112 of the reflector. The pitch angle of the optical path can be adjusted by rotating the first bolt c, the second bolt d and the third bolt e on the reflector body a.

[0048] The collimator base 5 has several arc-shaped U-shaped holes 52 with the same curvature along its circumference. The central arcs of all the arc-shaped U-shaped holes 52 are on the same circumference. The bolts pass through the arc-shaped U-shaped holes 52 to fix the collimator base 5 on the optical platform 7. The collimator base 5 can rotate slightly relative to the optical platform 7 within the curvature range of the arc-shaped U-shaped holes 52.

[0049] There are two ways to adjust the pitch angle:

[0050] The first method involves passing the first bolt c through the first through hole a3 and fixing it in the threaded hole a4, and passing the third bolt e through the through hole a8 and fixing it in the threaded hole a7. When both bolts are tightened simultaneously, the compression groove a5, i.e., the front side 111 of the reflector, moves closer to the rear side 112 of the reflector, thereby causing the front side 111 of the reflector to tilt backward, achieving upward refraction adjustment of the light path, which is the adjustment of the elevation angle of the light path. If only the first bolt c is tightened, the light path can be adjusted to the upper left. If only the third bolt e is tightened, the light path can be adjusted to the upper right. At this time, the left and right directions are the directions when facing the reflector.

[0051] The second method: After passing the second bolt d through the threaded hole a6, it rests against the rear side 112 of the reflector. By tightening the second bolt d, the tension groove a5 is opened, which moves the front side 111 of the reflector away from the rear side 112 of the reflector. This causes the front side 111 of the reflector to tilt forward, achieving downward refraction adjustment of the light path, which is the tilt angle adjustment of the light path. After tightening the second bolt d through the threaded hole a6, tighten the first bolt c fixed at the threaded hole a4 (the third bolt e is not used at this time), causing the front side 111 of the reflector to tilt backward to the upper left, which can achieve downward refraction adjustment of the light path. After tightening the second bolt d through the threaded hole a6, tighten the third bolt e fixed at the threaded hole a7 (the first bolt c is not used at this time), causing the front side 111 of the reflector to tilt backward to the upper right, which can achieve downward refraction adjustment of the light path. During operation, the number of reflectors can be adjusted according to actual needs, based on limiting factors such as the focal length of the lens, the divergence angle of the laser, and the focal length of the collimator. Using multiple reflectors for adjustment together allows for better control of the laser beam angle compared to adjusting a single reflector.

[0052] Preferably, the present invention uses three reflectors to achieve laser beam angle adjustment. The centers of all reflectors, light source generator 8 and collimator 6 are on the same horizontal plane. The light source generator 8 is used to generate and emit a laser beam. The laser beam is reflected sequentially by the first reflector 1, the second reflector 3 and the third reflector 4. By adjusting each reflector, the laser beam passes through the center of the collimator 6, improving the optical coupling efficiency. At the same time, by using multiple reflectors to cooperate in adjusting the laser beam's bending and pitch angles, the collimator adjustment dimensions can be effectively reduced, thereby reducing the calibration time.

[0053] The specific steps for adjusting the laser beam using this optical adjustment device are as follows:

[0054] 1. The light source generating device 8 emits a laser beam. By coarsely adjusting the relative fixed position of the arc-shaped U-shaped hole a1 on the first reflector 1, the second reflector 3, and the third reflector 4 and the optical platform 7, as well as the pitch angle of the optical path, the laser beam is irradiated in a 2mm-3mm area near the center point of the lens b of the first reflector 1, the second reflector 3, and the third reflector 4.

[0055] 2. By adjusting the relative fixed position of the arc-shaped U-shaped hole a1 on the first reflector 1 and the optical platform 7, the turning angle of the laser beam reflection is adjusted so that the laser beam generated by the light source generating device 8 irradiates the center position of the lens b of the first reflector 1, and the laser beam reflected by the first reflector 1 can irradiate the center of the lens b of the second reflector 3.

[0056] 3. A second reflector 3 is set in the direction of the laser beam reflected by the first reflector 1. By adjusting the relative fixed position of the arc-shaped U-shaped hole a1 on the first reflector 1 and the optical platform 7, and by adjusting the first bolt c, the second bolt d and the third bolt e of the first reflector 1, the laser beam reflected by the first reflector 1 can irradiate the center of the lens b of the second reflector 3, and the laser beam reflected by the second reflector 3 can irradiate the center of the lens b of the third reflector 4.

[0057] Specifically, (1) when the laser beam, after being reflected by the first reflector 1, does not pass through the center of the lens b of the second reflector 3 and instead irradiates the lower right of the center of the lens b of the second reflector 3, the direction of laser beam reflection can be adjusted by tightening the third bolt e of the first reflector 1 so that it eventually irradiates the center of the lens b of the second reflector 3; (2) similarly, if the laser beam irradiates the lower left of the center of the lens b of the second reflector 3, the direction of laser beam reflection can be adjusted by tightening the first bolt c of the first reflector 1 so that it eventually irradiates the center of the lens b of the second reflector 3; (3) if the laser beam irradiates the upper right of the center of the lens b of the second reflector 3, the direction of laser beam reflection can be adjusted by first tightening the second bolt d of the first reflector 1 and then tightening the third bolt e of the first reflector 1 so that it eventually irradiates the lens b of the second reflector 3. (4) If the laser beam is irradiated to the upper left of the center of the lens b of the second reflector 3, the direction of laser beam reflection can be adjusted by first tightening the second bolt d of the first reflector 1 and then tightening the first bolt c, so that it finally irradiates the center of the lens b of the second reflector 3; (5) If the laser beam is directly above the lens b of the second reflector 3, the direction of laser beam reflection can be adjusted by tightening the second bolt d of the first reflector 1, so that it finally irradiates the center of the lens b of the second reflector 3; (6) If the laser beam is directly below the lens b of the second reflector 3, the direction of laser beam reflection can be adjusted by simultaneously tightening the first bolt c and the third bolt e of the first reflector 1, so that it finally irradiates the center of the lens b of the second reflector 3; In the above, the reflector can achieve adjustment of any angle of the optical path up and down and left and right.

[0058] 4. A third reflector 4 is set in the direction of the laser beam reflected by the second reflector 3. If the laser beam reflected by the second reflector 3 does not irradiate the center of the lens b of the third reflector 4, the second reflector 3 is adjusted according to the method in step 3 so that the laser beam irradiates the center of the lens b of the third reflector 4.

[0059] 5. A collimator 6 is set in the direction of the laser beam reflected by the third reflecting mirror 4. When the laser beam does not pass through the center of the collimator 6, for example, when the reflected laser beam irradiates the horizontal position of the center of the collimator 6, the relative position of the arc-shaped U-shaped hole 52 on the collimator base 5 and the bolt fixing of the optical platform 7 can be adjusted to achieve the translation adjustment of the optical path so that the laser beam passes through the center of the collimator 6. For example, when the reflected laser beam irradiates above and below the center of the collimator 6, the third reflecting mirror 4 is adjusted according to the method in step 3 so that the laser beam passes through the center of the collimator 6. Then, the relative position of the arc-shaped U-shaped hole 52 on the collimator base 5 and the bolt fixing of the optical platform 7 is adjusted to achieve the translation adjustment of the optical path before coupling it into the optical fiber.

[0060] Example 2

[0061] The optical adjustment device proposed in Embodiment 1 is further expanded into a light source generation system to prepare a quantum entangled light source with an adjustable optical path. The light source generation device 8 emits pump light, which is reflected by a mirror to a BBO crystal. The mirror is adjusted so that the pump light is reflected to the center of the BBO crystal. After the spontaneous parametric down-conversion process of the BBO crystal, entangled photon pairs with a certain angle and spatial separation are prepared. The direction of travel of the entangled photon pairs is reflected and adjusted by the mirror, and after fine adjustment by the collimator, they are coupled to a single-mode fiber to perform single-photon detection and time coincidence measurement. This can verify the reliability and authenticity of the system in preparing a quantum entangled light source.

[0062] See Figure 5 The light source generating system includes a light source generating device 8, a first reflecting mirror 1, a convex lens 11, a second reflecting mirror 3, a third reflecting mirror 4-1, a fourth reflecting mirror 4-2, a first collimator 6-1, a second collimator 6-2, a first filter 12-1, a second filter 12-2, a first BBO crystal 15, a half-wave plate 16, a second BBO crystal 17-1, a third BBO crystal 17-2, a first polarizer 18-1, and a second polarizer 18-2. The structures of the first reflecting mirror 1, the second reflecting mirror 3, the third reflecting mirror 4-1, the fourth reflecting mirror 4-2, the light source generating device 8, the first collimator 6-1, and the second collimator 6-2 are all the same as the corresponding components in Embodiment 1, and are fixed to an optical platform using the same fixing method as in Embodiment 1.

[0063] in,

[0064] Light source generator 8: It uses a semiconductor laser with a maximum output power of 100mw, adjustable output power, and a center wavelength of 405nm. The light source generator 8 used in this system can directly output pump light.

[0065] First reflecting mirror 1: reflects the pump light generated by the light source generator 8.

[0066] Convex lens 11: positioned between the first reflecting mirror 1 and the second reflecting mirror 3 to focus the light spot.

[0067] Second reflecting mirror 3: reflects the light spot focused by convex lens 11, and adjusts the second reflecting mirror 3 to make it incident on the center of BBO crystal 15.

[0068] First BBO Crystal 15: The first BBO crystal 15 is the core of the entire system. A 2mm BBO crystal is selected. After the light spot passes through the 2mm first BBO crystal 15, a parametric downconversion process occurs, splitting it into a pair of entangled photons. That is, the two photons in the entangled state are emitted from two directions respectively. The emission direction of this pair of entangled photons and the incident direction of the light spot each form a 3° angle.

[0069] Half-wave plate 16: Placed at the light-emitting end of the first BBO crystal 15, the half-wave plate 16 is positioned at 45° in the system to perform polarization state transformation on entangled photons, and together with the second BBO crystal 17-1 or the third BBO crystal 17-2, it constitutes a compensation system.

[0070] The aforementioned light source generating device 8, first reflector 1, convex lens 11, second reflector 3, first BBO crystal 15, and half-wave plate 16 are arranged sequentially along the optical path 2. After polarization state transformation by the half-wave plate 16, a pair of entangled photons enter two branch optical paths respectively: the first branch optical path includes a third reflector 4-1, a second BBO crystal 17-1, a first polarizer 18-1, a first filter 12-1, and a first collimator 6-1 arranged sequentially along the optical path 2; the second branch optical path includes a fourth reflector 4-2, a third BBO crystal 17-2, a second polarizer 18-2, a second filter 12-2, and a second collimator 6-2 arranged sequentially along the optical path 2.

[0071] Third reflector 4-1 and fourth reflector 4-2: reflect entangled photons and change their travel path to facilitate subsequent collection and testing.

[0072] Second BBO crystal 17-1 and third BBO crystal 17-2: BBO crystals with a thickness of 1 mm are selected to compensate for some "walk-away" phenomena caused by the first BBO crystal 15 (2 mm thick) being a birefringent crystal, thereby improving the entanglement characteristics of the entanglement source.

[0073] First polarizer 18-1 and second polarizer 18-2: polarization basis vector measurement device. By rotating the polarizer to an angle of θ = {0°(H), 45°(D), 90°(V), 135°(A)}, the projection of the beam in the θ direction can be measured directly.

[0074] First filter 12-1 and second filter 12-2: used to filter out pump light and external stray light.

[0075] First collimator 6-1 and second collimator 6-2: as optical receiving couplers, they couple entangled photons in space to the optical fiber, thereby transmitting them to the coincidence counter 13.

[0076] The coincidence counter 13 uses the first single-photon detector 19 and the second single-photon detector 20 to detect the two entangled photons, thereby performing coincidence count measurements (measuring the number of photons arriving simultaneously from both paths) and reporting the data to the host computer 22. The host computer 22 then plots a histogram of the coincidence counts of the entangled photon pairs under different polarization measurement basis vectors based on the coincidence count values.

[0077] The specific working process of the light source generation system is as follows: The light source generating device 8 emits pump light, which is reflected by the first reflecting mirror 1, focused by the convex lens 11, and then incident on the first BBO crystal 15 after the transmission path is changed by the second reflecting mirror 3, so that the focus can be on the first BBO crystal 15. The focal length of the convex lens 11 selected in this invention is 200mm, and the optical path distance between the convex lens 11 and the first BBO crystal 15 is required to be 200mm. In order to miniaturize the device, a second reflecting mirror 3 is added between the convex lens 11 and the first BBO crystal 15 to change the propagation direction of the beam and adjust the beam angle so that the beam can illuminate the center of the first BBO crystal 15. After the beam undergoes spontaneous parametric down-conversion by the first BBO crystal 15, it is split into a pair of entangled photons. The two entangled photons are compensated by a half-wave plate 16 and a second BBO crystal 17-1 and a third BBO crystal 17-2, respectively. After polarization rotation by the half-wave plate 16, a third reflector 4-1 and a fourth reflector 4-2 are positioned 200mm from the travel path of the two entangled photons. After reflection by the third reflector 4-1 and the fourth reflector 4-2 and adjustment of the optical path angle, the two entangled photons respectively illuminate the second BBO crystal 17-1 and the third BBO crystal 17-2. At center 7-2, the pump light and stray light from the outside are filtered out by the first polarizer 18-1 and the second polarizer 18-2, respectively, and then by the first filter 12-1 and the second filter 12-2, respectively. Finally, the two entangled photons are coupled from the spatial light to the optical fiber by the first collimator 6-1 and the second collimator 6-2, respectively, and then transmitted to the coincidence counter 13. The first single-photon detector 19 and the second single-photon detector 20 are used to detect the two entangled photons respectively and perform coincidence count measurement (referring to measuring the number of photons that arrive at the same time). After that, the data is reported to the host computer 22.

[0078] Optional, such as Figure 6 As shown, a third polarizer 14-1 and a fourth polarizer 14-2 are added to the above-mentioned light source generation system. These are respectively positioned between the second BBO crystal 17-1 and the first polarizer 18-1, and between the third BBO crystal 17-2 and the second polarizer 18-2. The third polarizer 14-1 and the fourth polarizer 14-2 are rotated to 0° and 90° respectively, so that one photon is in the H-polarization state and the other photon is in the V-polarization state. At this point, a |HV> photon pair is prepared. The prepared |HV> photon pair is separable and can represent a classical light source. From the above scheme, it can be seen that when the third polarizer 14-1 and the fourth polarizer 14-2 are not placed in optical path 2, this invention is used to prepare entangled photon pairs.

[0079] When preparing entangled photon pairs, for example, the prepared entangled state is At that time, measurements are performed on the two paths of entangled photons under four basis vectors: HV, VH, DA, and AD (for example, adjusting the first polarizer 18-1 and the second polarizer 18-2 to 0° and 90° respectively is equivalent to measuring under the HV basis vector; adjusting the first polarizer 18-1 and the second polarizer 18-2 to 90° and 0° respectively is equivalent to measuring under the VH basis vector; adjusting the first polarizer 18-1 and the second polarizer 18-2 to 45° and 135° respectively is equivalent to measuring under the DA basis vector; adjusting the first polarizer 18-1 and the second polarizer 18-2 to 135° and 45° respectively is equivalent to measuring under the AD basis vector). The coincidence count values ​​under the four basis vectors are obtained and reported to the host computer 22 in real time. Due to the entangled state... The collapse probability under the HV, VH, DA, and AD basis vectors is 1 / 2. Therefore, the host computer 22 uses the coincidence count value to plot the histogram of the coincidence count of the entangled photon pair under different polarization measurement basis vectors, as follows. Figure 7 As shown on the left.

[0080] When a third polarizer 14-1 and a fourth polarizer 14-2 are added to the two paths of entangled photons, and the third polarizer 14-1 and the fourth polarizer 14-2 are rotated to 0° and 90° respectively, so that one photon is in the H polarization state and the other photon is in the V polarization state, a |HV> photon pair is prepared. The prepared |HV> photon pair is separable and can represent a classical light source. Similarly, the |HV> photon pair is measured under four basis vectors: HV, VH, DA, and AD. Since the first single-photon detector 19 and the second single-photon detector 20 have almost no counts when measuring the |HV> photon pair using the VH basis, the |HV> photon pair has no coincidence count under the VH basis. When the DA basis or the AD basis is used for measurement, because... Meanwhile, since the |HV> photon pairs prepared in this optical path are entangled... The coincidence count of the |HV> photon pair is half that of the |HV> photon pair measured using the DA and AD basis vectors, therefore it is 1 / 4 of the coincidence count under the |HV> basis vectors. The host computer 22 plots a histogram of the coincidence count of the |HV> photon pair under different polarization measurement basis vectors based on the coincidence count value, as follows: Figure 7 As shown on the right.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical adjustment device, characterized in that: The system includes an optical platform (7) and a light source generating device (8), a first reflector (1), a second reflector (3), a third reflector (4), and a collimator (6) that are sequentially fixed to the optical platform (7) along the optical path. The first reflector (1), the second reflector (3), and the third reflector (4) have the same structure, including a reflector body (a) and a lens (b) respectively. The upper part of the reflector body (a) is provided with a groove (a5) from top to bottom. The groove (a5) divides the upper part of the reflector body (a) into a front side (111) and a rear side (112) of the reflector. The lens (b) is set on the front side (111) of the reflector. The bottom end of the front side (111) of the reflector is connected to the rear side (112) of the reflector. By adjusting the position of the front side (111) of the reflector relative to the rear side (112) of the reflector, the pitch angle of the optical path can be adjusted.

2. The optical adjustment device as described in claim 1, characterized in that: The lower part of the main body (a) of the reflector is a base, and at least one first arc-shaped U-shaped hole (a1) is opened in the base along the circumference. The first reflector (1), the second reflector (3), and the third reflector (4) are fixed on the optical platform (7) by bolts passing through the corresponding first arc-shaped U-shaped hole (a1).

3. The optical adjustment device as described in claim 2, characterized in that: The collimator (6) is fixed on the collimator base (5). Several second arc-shaped U-shaped holes (52) with the same arc are opened on the collimator base (5) along the circumference. The center arc of all the second arc-shaped U-shaped holes (52) is on the same circumference. The bolt passes through the second arc-shaped U-shaped holes (52) to fix the collimator base (5) on the optical platform (7).

4. The optical adjustment device as described in claim 2 or 3, characterized in that: The arc of each U-shaped hole is the same. The center arc of all the first U-shaped holes (a1) is on the same circumference and the U-shaped holes are evenly distributed. The center arc of all the second U-shaped holes (52) is on the same circumference and the U-shaped holes are evenly distributed.

5. The optical adjustment device as described in claim 1, characterized in that: The reflector body (a) has a lens hole (a2) in the middle, and the lens (b) is glued to the lens hole (a2) of the reflector body (a).

6. The optical adjustment device as described in claim 1, characterized in that: The centers of all the reflectors, light source generators (8), and collimators (6) are on the same horizontal plane.

7. The optical adjustment device as described in claim 1, characterized in that: The front side (111) of the reflector has a first through hole (a3) ​​and a third through hole (a8) on both sides of the upper part, and a second threaded hole (a6) in the middle. The rear side (112) of the reflector has a first threaded hole (a4) and a third threaded hole (a7) at the positions corresponding to the first through hole (a3) ​​and the third through hole (a8). The first bolt (c) can pass through the first through hole (a3) ​​and be screwed into the first threaded hole (a4). The third bolt (e) can pass through the third through hole (a8) and be screwed into the third threaded hole (a7). The second bolt (d) can be screwed into the second threaded hole (a6) and its rear end abuts against the rear side (112) of the reflector.

8. The optical adjustment device as described in claim 7, characterized in that: There are two ways to adjust the pitch angle of the optical path: The first method: The first bolt (c) is passed through the first through hole (a3) ​​and fixed in the first threaded hole (a4), and the third bolt (e) is passed through the through hole (a8) and fixed in the third threaded hole (a7). When these two bolts are tightened at the same time, the compression groove (a5), that is, the front side (111) of the reflector, moves closer to the rear side (112) of the reflector, thereby causing the front side (111) of the reflector to tilt backward, realizing the upward refraction adjustment of the light path, which is the adjustment of the elevation angle of the light path. If only the first bolt (c) is tightened, the light path will be adjusted to refract upwards to the left; if only the third bolt (e) is tightened, the light path will be adjusted to refract upwards to the right. The second method: After passing the second bolt (d) through the second threaded hole (a6), it is placed against the rear side (112) of the reflector. By tightening the second bolt (d), the tension groove (a5) is opened, which causes the front side (111) of the reflector to move away from the rear side (112) of the reflector, thereby tilting the front side (111) of the reflector forward and adjusting the downward refraction of the light path, which is the adjustment of the downward angle of the light path. After tightening the second bolt (d) that passes through the second threaded hole (a6), the first bolt (c) fixed at the first threaded hole (a4) is tightened, causing the front side (111) of the reflector to tilt backward in the upper left direction, thereby adjusting the refraction of the light path to the lower left. After tightening the second bolt (d) that passes through the second threaded hole (a6), the third bolt (e) fixed at the third threaded hole (a7) is tightened, causing the front side (111) of the reflector to tilt backward in the upper right direction, thereby adjusting the refraction of the light path to the lower right.

9. The optical adjustment device as described in claim 8, characterized in that: The specific steps for adjusting the laser beam using this optical adjustment device are as follows: Step 1: The light source generating device (8) emits a laser beam. By coarsely adjusting the relative fixed position of the first reflector (1), the second reflector (3), and the third reflector (4) with the optical platform (7) and the pitch angle of the optical path, the laser beam is irradiated in a 2mm-3mm area near the center point of the lens (b) of the first reflector (1), the second reflector (3), and the third reflector (4). Step 2: By adjusting the relative fixed position of the first reflector (1) and the optical platform (7), the turning angle of the laser beam reflection is adjusted so that the laser beam generated by the light source generating device (8) irradiates the center position of the lens b of the first reflector (1), and the laser beam reflected by the first reflector (1) can irradiate the center of the lens (b) of the second reflector (3). Step 3: By adjusting the relative fixed position of the first reflector (1) and the optical platform (7), and by adjusting the first bolt (c), the second bolt (d) and the third bolt (e) of the first reflector (1), the laser beam reflected by the first reflector (1) can illuminate the center of the lens (b) of the second reflector (3), and the laser beam reflected by the second reflector (3) can illuminate the center of the lens (b) of the third reflector (4). Specifically, (1) when the laser beam, after being reflected by the first reflector (1), does not pass through the center of the lens (b) of the second reflector (3) and instead irradiates the lower right of the center of the lens (b) of the second reflector (3), the direction of laser beam reflection is adjusted by tightening the third bolt (e) of the first reflector (1) so that it ultimately irradiates the center of the lens (b) of the second reflector (3); (2) similarly, if the laser beam irradiates the lower left of the center of the lens (b) of the second reflector (3), the direction of laser beam reflection is adjusted by tightening the first bolt (c) of the first reflector (1) so that it ultimately irradiates the center of the lens (b) of the second reflector (3); (3) if the laser beam irradiates the upper right of the center of the lens (b) of the second reflector (3), the direction of laser beam reflection is adjusted by first tightening the second bolt (d) of the first reflector (1) and then tightening the third bolt (e) of the first reflector (1) so that it ultimately irradiates the center of the lens (b) of the second reflector (3). (3) Center of lens (b) of reflector (3); (4) If the laser beam is irradiated to the upper left of the center of lens (b) of the second reflector (3), the laser beam reflection direction is adjusted by first tightening the second bolt (d) of the first reflector (1) and then tightening the first bolt (c) so that it finally irradiates the center of lens (b) of the second reflector (3); (5) If the laser beam is directly above the lens (b) of the second reflector (3), the laser beam reflection direction is adjusted by tightening the second bolt (d) of the first reflector (1) so that it finally irradiates the center of lens (b) of the second reflector (3); (6) If the laser beam is directly below the lens (b) of the second reflector (3), the laser beam reflection direction is adjusted by simultaneously tightening the first bolt (c) and the third bolt (e) of the first reflector (1) so that it finally irradiates the center of lens (b) of the second reflector (3); In the above, the pitch angle of the optical path is adjusted. Step 4: If the laser beam reflected by the second reflector (3) does not irradiate the center of the lens (b) of the third reflector (4), adjust the second reflector (3) according to the method in step 3 so that the laser beam irradiates the center of the lens (b) of the third reflector (4). Step 5: Set a collimator (6) in the direction of the laser beam reflected by the third reflecting mirror (4). When the laser beam does not pass through the center of the collimator (6), adjust the relative position of the collimator (6) and the optical platform (7) to achieve the translation adjustment of the optical path so that the laser beam passes through the center of the collimator (6). If the reflected laser beam irradiates above and below the center of the collimator (6), adjust the third reflecting mirror (4) according to the method in step 3 so that the laser beam passes through the center of the collimator (6), and then adjust the relative position of the collimator (6) and the optical platform (7) to achieve the translation adjustment of the optical path.

10. A light source generating system, characterized in that: The light source includes a light source generating device (8), a first reflector (1), a convex lens (11), a second reflector (3), a first BBO crystal (15), and a half-wave plate (16) arranged sequentially along the optical path (2). After passing through the first BBO crystal (15), the light path splits into two branch paths. The two branch paths pass through the half-wave plate (16) simultaneously. The first branch path includes a third reflector (4-1), a second BBO crystal (17-1), a first polarizer (18-1), a first filter (12-1), and a first collimator (6-1) arranged sequentially along the optical path (2). The second branch path includes a fourth reflector (4-2), a third BBO crystal (17-2), and a second polarizer (18-2) arranged sequentially along the optical path (2). The second filter (12-2) and the second collimator (6-2) have the same structure as the first reflector (1), the second reflector (3), the third reflector (4-1), and the fourth reflector (4-2), which respectively include a reflector body (a) and a lens (b). The upper part of the reflector body (a) is provided with a groove (a5) from top to bottom. The groove (a5) divides the upper part of the reflector body (a) into a front side (111) and a rear side (112) of the reflector. The lens (b) is set on the front side (111) of the reflector. The bottom end of the front side (111) of the reflector is connected to the rear side (112) of the reflector. By adjusting the position of the front side (111) of the reflector relative to the rear side (112) of the reflector, the pitch angle of the optical path (2) can be adjusted.

11. The light source generating system as described in claim 10, characterized in that: The working process of the light source generation system is as follows: The light source generating device (8) emits pump light, which is reflected by the first reflector (1), focused by the convex lens (11), and then incident on the first BBO crystal (15) after the transmission path is changed by the second reflector (3). The second reflector (3) is adjusted so that the light beam can illuminate the center of the first BBO crystal (15). After passing through the first BBO crystal (15), the light beam is split into a pair of entangled photons, which are polarized and rotated by the half-wave plate (16) and then enter the third reflector (4-1) and the fourth reflector (4-2) respectively. The light beam is reflected by the third reflector (4-1) and the fourth reflector (4-2) respectively. After angle adjustment, the two entangled photons are respectively irradiated by the centers of the second BBO crystal (17-1) and the third BBO crystal (17-2). After passing through the first polarizer (18-1) and the second polarizer (18-2), they are filtered by the first filter (12-1) and the second filter (12-2) to remove pump light and external stray light. Finally, the two entangled photons are coupled from spatial light to the optical fiber by the first collimator (6-1) and the second collimator (6-2) to prepare entangled photon pairs. The first polarizer (18-1) and the second polarizer (18-2) are polarization basis vector measurement devices used to measure the entangled state of the two entangled photons.

12. The light source generating system as described in claim 10, characterized in that: It also includes a set of polarizers: a third polarizer (14-1) and a fourth polarizer (14-2), which are respectively disposed between the second BBO crystal (17-1) and the first polarizer (18-1) and between the third BBO crystal (17-2) and the second polarizer (18-2).

13. The light source generating system as described in claim 12, characterized in that: The working process of the light source generation system is as follows: The light source generating device (8) emits pump light, which is reflected by the first reflector (1), focused by the convex lens (11), and then incident on the first BBO crystal (15) after the transmission path is changed by the second reflector (3). The second reflector (3) is adjusted so that the light beam can illuminate the center of the first BBO crystal (15). After passing through the first BBO crystal (15), the light beam is split into a pair of entangled photons. After being polarized and rotated by the half-wave plate (16), the photons enter the third reflector (4-1) and the fourth reflector (4-2) respectively. After being reflected by the third reflector (4-1) and the fourth reflector (4-2) respectively and the optical path angle is adjusted, the two entangled photons illuminate the centers of the second BBO crystal (17-1) and the third BBO crystal (17-2) respectively. After passing through the third polarizer (14-1) and the third polarizer (14-2) respectively, the two entangled photons illuminate the centers of the second BBO crystal (17-1) and the third BBO crystal (17-2) respectively. After passing through the fourth polarizer (14-2), the light then passes through the first polarizer (18-1) and the second polarizer (18-2), and then through the first filter (12-1) and the second filter (12-2) to filter out the pump light and external stray light. Finally, the two entangled photons are coupled from the spatial light to the optical fiber through the first collimator (6-1) and the second collimator (6-2), respectively. The third polarizer (14-1) and the fourth polarizer (14-2) are rotated to 0° and 90°, respectively, so that one entangled photon is in the H polarization state and the other entangled photon is in the V polarization state. At this time, the |HV> photon pair is prepared. The prepared |HV> photon pair is a separable state, representing a classical light source. The first polarizer (18-1) and the second polarizer (18-2) are polarization basis vector measurement devices used to measure the polarization state of the two classical light sources.

14. The light source generating system as described in claim 10, characterized in that: The first BBO crystal (15) is a 2mm BBO crystal, the second BBO crystal (17-1) and the third BBO crystal (17-2) are BBO crystals with a thickness of 1mm, the convex lens (11) has a focal length of 200mm, the optical path distance between the convex lens (11) and the first BBO crystal (15) is 200mm, and the optical path distance between the first BBO crystal (15) and the third reflector (4-1) and the fourth reflector (4-2) is 200mm.

15. The light source generating system as described in claim 11 or 13, characterized in that: It also includes a coincidence counter (13) and a host computer (22). The first collimator (6-1) and the second collimator (6-2) couple two entangled photons from spatial light to optical fiber and transmit them to the coincidence counter (13). The coincidence counter (13) uses the first single-photon detector (19) and the second single-photon detector (20) to detect the two entangled photons or the two classical light sources respectively, and after performing coincidence count measurement, it reports the data to the host computer (22). The host computer (22) draws a histogram of the coincidence count of the entangled photon pair or the classical light source under different polarization measurement basis vectors based on the coincidence count value.

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