Free space circulator
By processing the surface of the polarized spectroscopic prism into a small wedge angle in a free space circulator and glued it with other optical components, the problems of large and low return loss of the existing circulator are solved, achieving lower cost high return loss and low Ripple effects.
Patent Information
- Application Number
- CN202421809451.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-29
- Publication Date
- 2025-05-13
- Estimated Expiration
- 2034-07-29
AI Technical Summary
The existing free space circulators have shortcomings in Ripple and return loss. Ripple is larger, return loss is lower, and cost is higher.
A new free space circulator is formed by machining one face of the polarization spectroscopy into a small wedge angle and glued with the Faraday rotary sheet and the half wave plate.
Reduces Ripple, improves return loss, and the design is easy to process, controllable cost, and can achieve better performance at lower costs.
Smart Images
Figure CN222866968U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of optical communication devices, in particular to a free space circulator. Background Art
[0002] Existing conventional free-space circulators, such as Figures 1 to 4 As shown, the circulator is made of a polarization beam splitter prism 101, a half wave plate 102, a Faraday rotator 103, and another polarization beam splitter prism 104 glued together, and the glued planes of each sub-component are parallel to each other. This circulator has the following shortcomings: Large Ripple: The value is generally around 0.12dB. The sub-components that make up the circulator, the two polarization beam splitters, the Faraday rotator, and the half wave plate, have glued interfaces that are parallel to each other. Light will reflect back and forth between these planes, and then interfere, thereby generating a large Ripple; Low return loss: Under normal application conditions, it is generally required that the incident light beam and the incident plane of the polarization beam splitter prism be incident at a 0-degree angle (normal incidence) so that the polarization beam splitter prism can work at the maximum extinction ratio, thereby obtaining the best isolation, but normal incidence will sacrifice the performance of return loss, resulting in low return loss. Utility Model Content
[0003] The technical problem to be solved by the utility model is to provide a free space circulator, which reduces ripple, improves return loss and reduces cost at the same time.
[0004] The utility model is implemented as follows: a free space circulator, the free space circulator is formed by gluing a polarization beam splitter prism, a Faraday rotator, and a half wave plate from left to right;
[0005] The polarization beam splitter prism is configured to form a wedge angle surface with an angle of α on a surface glued to the Faraday rotator.
[0006] Furthermore, the angle α is set between 1° and 10°.
[0007] Furthermore, the rotation angle of the Faraday rotator is 45°, and the half-wave plate is a half-wave plate in which the angle between the optical axis of the wave plate and the edge of the wave plate is 22.5°.
[0008] Furthermore, the Faraday rotator is a latching type Faraday rotator.
[0009] Furthermore, the Faraday rotator is a non-latching type Faraday rotator, and at least one magnetic block or magnetic ring is disposed outside the Faraday rotator for providing a magnetic field required for the non-latching type Faraday rotator to work.
[0010] Furthermore, the Faraday rotator is a BIG Garnet type crystal.
[0011] Furthermore, the half wave plate is a true zero-order half wave plate or a low-order half wave plate or an achromatic half wave plate.
[0012] Furthermore, the polarization beam splitter prism is formed by bonding the oblique surfaces of two right-angle prisms to each other, and the oblique surface of one of the right-angle prisms is coated with a polarization beam splitter film.
[0013] The utility model has the following advantages: by processing one of the faces of the polarization beam splitter prism into a small wedge angle, the return loss of the free space ring is increased and the ripple is reduced; the free space circulator of the utility model is easy to process and the cost is controllable, and better performance can be achieved at a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The present invention will be further described below in conjunction with the embodiments with reference to the accompanying drawings.
[0015] Figure 1 It is a schematic diagram of the three-dimensional structure of a conventional free space circulator in the prior art;
[0016] Figure 2 for Figure 1 A front view of
[0017] Figure 3 for Figure 1 Left view of
[0018] Figure 4 for Figure 1 A top view of
[0019] Figure 5 The utility model is a three-dimensional structural schematic diagram of a free space circulator with low ripple and high return loss.
[0020] Figure 6 for Figure 5 A top view of
[0021] Figure 7 for Figure 5 Left view of
[0022] Figure 8 for Figure 5 A front view of
[0023] Fig. 9 It is a schematic diagram of the change of polarization state in a specific embodiment of the utility model;
[0024] Fig.10 It is a schematic diagram of the change of polarization state in another specific embodiment of the utility model. DETAILED DESCRIPTION
[0025] See also Figures 6 to 8 As shown, the utility model provides a free-space circulator, which is formed by gluing a polarization beam splitter prism 201, a Faraday rotator 202, and a half-wave plate 203 from left to right;
[0026] The polarization beam splitter prism 201 is configured to form a wedge angle surface with an angle of α on a surface glued to the Faraday rotator 202 .
[0027] In a specific embodiment, the angle α is set between 1° and 10°, so that the light beam is no longer incident perpendicularly on each bonding interface, thereby eliminating the interference caused by the back and forth reflection of light between parallel interfaces and the resulting ripples. At the same time, the return loss of the common port is greatly improved due to the existence of the wedge angle.
[0028] In a specific embodiment, the rotation angle of the Faraday rotator 202 is 45° (ie, its rotation angle is 45° under magnetic saturation), and the half wave plate 203 is a half wave plate with an angle of 22.5° between the wave plate optical axis and the wave plate edge.
[0029] In one embodiment, the Faraday rotator 202 is a latching type Faraday rotator.
[0030] In a specific embodiment, the Faraday rotator 202 is a non-latching Faraday rotator, and at least one magnetic block or magnetic ring is disposed outside the Faraday rotator for providing a magnetic field required for the non-latching Faraday rotator to work.
[0031] In one embodiment, the Faraday rotator 202 is a BIG Garnet type crystal.
[0032] In a specific embodiment, the half wave plate 203 is a true zero-order half wave plate or a low-order half wave plate or an achromatic half wave plate.
[0033] In a specific embodiment, the polarization beam splitter prism 201 is formed by bonding the oblique surfaces of two right-angle prisms to each other, and one of the oblique surfaces of the right-angle prism is coated with a polarization beam splitter film.
[0034] Combine the following Fig. 9 and Fig.10 The working principle of the free space circulator of the utility model is described as follows:
[0035] During forward transmission, S-polarized light enters the optical circulator from Port 1, is reflected by the polarization beam splitter 201, and then passes through the Faraday rotator 202 and the half-wave plate 203 in sequence, and then enters the common port Port 2 as S-polarized light.
[0036] During forward transmission, S polarized light enters the optical circulator from Port 2, enters the half-wave plate 203, and then passes through the Faraday rotator 202, where the polarization direction is rotated 90°, transforming from S light to P light. After being transmitted along a straight line through the polarization beam splitter prism 201, it enters Port 3 as P polarized light.
[0037] In the above, light ringing is realized during forward transmission, that is, forward transmission from port Port 1 to port Port 2, and forward transmission from port Port 2 to port Port 3.
[0038] During reflection transmission, S polarized light enters the optical circulator from Port 2, enters the half-wave plate 203, and then passes through the Faraday rotator 202. The polarization direction is rotated 90°, and the S light is transformed into P light. After being transmitted along a straight line through the polarization beam splitter prism 201, it enters Port 3 as P polarized light and cannot be transmitted back to Port 1. Therefore, the isolation of reverse transmission Port2–>Port 1 is achieved.
[0039] During reflection transmission, P polarized light enters the optical circulator from Port 3, transmits along a straight line through the polarization beam splitter 201, and is incident on the Faraday rotator 202 as P polarized light. After passing through the half-wave plate 203, its polarization direction remains unchanged and is incident on Port 2 as P light. Since the polarization state of the light is perpendicular to that of Port 2, the light cannot be effectively coupled to Port 2, thereby achieving isolation of reverse transmission Port 3–>Port 2.
[0040] When the rotation angle of the Faraday rotator 202 is 45° clockwise, the angle between the optical axis of the half wave plate 203 and the horizontal direction is 22.5°. Fig. 9 As shown, the S polarized light is parallel to the short side of the rectangle in the figure, and the P polarized light is parallel to the long side of the rectangle in the figure.
[0041] When the rotation angle of the Faraday rotator 202 is 45° counterclockwise, the angle between the optical axis of the half wave plate 203 and the vertical direction is 22.5°. Fig.10 As shown, similarly, the S polarized light is parallel to the short side of the rectangle in the figure, and the P polarized light is parallel to the long side of the rectangle in the figure.
[0042] Fig. 9 and Fig.10The two combinations shown can both achieve the above-mentioned forward transmission and reverse isolation.
[0043] The free-space circulator of the present invention can achieve Ripple<0.03dB within the working wavelength range of 50nm, while the conventional free-space circulator Ripple<0.12dB, so it has a lower Ripple. The return loss of a conventional free-space circulator can only reach 40dB, and the return loss RL of the free-space circulator of the present invention within the working wavelength range of 50nm is>50dB; the present invention glues the most conventional Faraday rotator, polarizer and half-wave plate by utilizing a gluing process, and only needs to process one surface of the polarization beam splitter prism into a small wedge angle, so that the glued free-space circulator has a smaller arc, which not only meets the isolation requirements but also obtains the above excellent performances of high return loss and low Ripple, and is easy to process and has controllable costs.
[0044] Although the specific implementation methods of the present invention are described above, those skilled in the art should understand that the specific embodiments described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.
Claims
1. A free space circulator, characterized in that: The free-space circulator is composed of a polarization beam splitter prism, a Faraday rotator, and a half-wave plate glued together from left to right; The polarization beam splitter prism is configured to form a wedge angle surface with an angle of α on a surface glued to the Faraday rotator.
2. A free space circulator according to claim 1, characterized in that: The angle α is set between 1° and 10°.
3. A free space circulator according to claim 1, characterized in that: The rotation angle of the Faraday rotator is 45°, and the half-wave plate is a half-wave plate in which the angle between the optical axis of the wave plate and the edge of the wave plate is 22.5°.
4. A free space circulator as claimed in claim 1, characterized in that: The Faraday rotator is a latching type Faraday rotator.
5. A free space circulator as claimed in claim 1, characterized in that: The Faraday rotator is a non-latching type Faraday rotator, and at least one magnetic block or magnetic ring is arranged outside the Faraday rotator for providing a magnetic field required for the non-latching type Faraday rotator to work.
6. A free space circulator as claimed in claim 1, characterized in that: The Faraday rotator is a BIGGarnet type crystal.
7. A free space circulator as claimed in claim 1, characterized in that: The half wave plate is a true zero-order half wave plate or a low-order half wave plate or an achromatic half wave plate.
8. A free space circulator as claimed in claim 1, characterized in that: The polarization beam splitter prism is formed by bonding the oblique surfaces of two right-angle prisms to each other, and the oblique surface of one of the right-angle prisms is coated with a polarization beam splitter film.