A noise optical isolator based on Heriot-Limiter multi-pass pool

Abstract

This invention relates to the field of noise light processing technology, specifically providing a noise light isolator based on a Heriot-Limiter multi-pass cell for filtering noise light contained in light from a light source. The isolator includes a Heriot-Limiter multi-pass cell, an absorption cell, and a filter medium. The Heriot-Limiter multi-pass cell includes a first concave mirror and a second concave mirror, with an entrance aperture and an exit aperture respectively located at their edges. The absorption cell is located between the first and second concave mirrors and contains the filter medium. Light from the light source enters the Heriot-Limiter multi-pass cell through the entrance aperture and is repeatedly reflected between the first and second concave mirrors before exiting the cell through the exit aperture. During each reflection, the light from the light source passes through the filter medium in the absorption cell, thus filtering out noise light from the light source. This invention significantly increases the optical path length of the light source in the absorption cell, achieving saturable absorption of small-signal noise light and effectively improving noise light isolation.

Description

Technical Field

[0001] This invention relates to the field of noise optical processing technology, specifically providing a noise optical isolator based on a Heriot-Limiter multipass cell. Background Technology

[0002] Extreme ultraviolet (EUV) lithography is a core process for mass production of semiconductor chips at 5nm and below. Its light source relies on plasma radiation generated by the interaction of a high-power, high-repetition-rate (>50kHz) pulsed carbon dioxide laser (wavelength 10.6μm) with a tin droplet target. To achieve stable output of 13.5nm EUV light, the carbon dioxide laser system needs to employ a master oscillator power amplifier (MOPA) architecture. This involves a master oscillator generating low-power seed light, which is then progressively boosted to megawatt-level peak power by multiple power amplifier stages. However, stray light signals generated during multi-stage amplification, such as spontaneous emission amplification (ASE) noise light and residual light reflected from optical elements, can form positive feedback loops in high-gain amplifiers, causing system power fluctuations, mode competition, and even self-oscillation, threatening the stability of the MOPA link. Therefore, high-isolation optical isolators must be placed between adjacent amplification stages to block the back-propagating noise light.

[0003] Traditional laser isolators are mostly based on the Faraday magneto-optical effect, but there are no mature magneto-optical crystal materials for long-wavelength carbon dioxide lasers (10.6 μm). The current mainstream approach uses an optical isolator based on the saturable absorption effect of sulfur hexafluoride (SF6) gas. Its working principle is as follows: when a high-power laser pulse passes through SF6 gas, the gas molecules are excited to a high energy state (vibrational-rotational energy level) due to stimulated emission, causing a sharp decrease in the absorption coefficient (bleaching effect), allowing the main pulse to pass through with low loss. During the pulse interval, SF6 rapidly relaxes to its ground state through a vibrational-translational (VT) energy transfer process, restoring its high absorption characteristics for small-signal noise light (absorption coefficient...). This enables the power selective isolation function of "high-power pulses passing through with low loss and low-power noise blocking with high loss".

[0004] However, sulfur hexafluoride saturable absorber isolators have the following drawbacks: An inherent contradiction between the small-signal absorption coefficient and insertion loss: noise light absorption depends on stimulated emission, while recovery depends on vibrational energy transfer and VT energy transfer. Increasing gas pressure and adding buffer gas can improve the small-signal noise light absorption rate, but will reduce the transmittance. Problems arising from increasing the absorption cell length: While increasing the absorption cell length can improve the isolation of small-signal noise lasers and the contrast between the absorption coefficients of small-signal noise light and pulsed lasers, excessively long multi-pass cells occupy a large space, are difficult to assemble and adjust, and the longer the straight-through optical path, the higher the probability of beam distortion (especially for circulating isothermal saturable absorber isolators). The difficulty of increasing energy density through focusing: Increasing the energy density in the absorption region of the sulfur hexafluoride absorption cell through focusing can increase isolation without increasing insertion loss, but it is limited by the diffraction characteristics of long-wavelength lasers, making it difficult to maintain a small beam size over long distances (the divergence angle of a 10.6 μm carbon dioxide laser is ten times that of a 1 μm laser).

[0005] Existing sulfur hexafluoride saturable absorber isolators suffer from the following core contradiction: there is a negative correlation between isolation (ISO) and insertion loss (IL). Specifically, increasing the optical path length improves isolation but leads to increased insertion loss and expansion of the absorption cell volume; increasing the gas pressure or adding a buffer gas (such as He, ...) also contributes to this problem. While it can shorten the relaxation time, it will reduce the transmittance of the main pulse. Although the focusing optical path can locally enhance the absorption nonlinearity, it is limited by the diffraction characteristics of long-wavelength lasers, making it difficult to achieve synergistic optimization of long optical path and high energy density. This contradiction seriously restricts the application of sulfur hexafluoride saturable absorber isolators in next-generation EUV laser systems.

[0006] In summary, there is an urgent need for a novel saturable absorber design that can achieve high isolation (ISO>30dB), low insertion loss (IL<5%), and high damage threshold within a compact space. Breakthrough in synergistic performance. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a noise optical isolator based on a Heriot-Limited Cell, which combines a Heriot-Limited Cell with an absorption cell. This allows the light from the light source to pass through the absorption cell during repeated refraction, filtering out noise light and achieving saturable absorption of small-signal noise light, thus effectively improving the noise optical isolation.

[0008] The noise optical isolator based on Heriot-Limiter multipass cell provided by this invention is used to filter noise light contained in the light source, comprising:

[0009] Heriot multi-pass tank, absorption tank and filter media;

[0010] The light from the source can be repeatedly reflected inside the Heriotte multi-pass pool;

[0011] The absorption tank is located inside the Heriot multi-pass tank, and the absorption tank is equipped with filter media.

[0012] Each time the light from the light source is reflected, it passes through the filter medium in the absorption cell, which is used to filter out noise light from the light source.

[0013] Preferably, the Heriot-style multi-pass cell includes a first concave mirror and a second concave mirror, the first and second concave mirrors are coaxial, and the light from the light source is repeatedly reflected between the first and second concave mirrors.

[0014] Preferably, a light inlet is provided at the edge of the first concave mirror, and a light outlet is provided at the edge of the second concave mirror. The light from the light source enters the Heriot-Limited Cell through the light inlet, and after repeated reflections, leaves the Heriot-Limited Cell through the light outlet.

[0015] Preferably, the light from the light source is repeatedly reflected to form multiple reflection points, and the diameters of the light inlet and light outlet are both smaller than the distance between any two adjacent reflection points.

[0016] Preferably, the surfaces of the first and second concave mirrors are coated with a high-reflectivity film to enhance the reflection of light from the light source.

[0017] Preferably, the absorption cell is located at the geometric center between the first concave mirror and the second concave mirror.

[0018] Preferably, the focal point of the light from the light source after each reflection is located in the middle of the absorption cell and forms the focal plane.

[0019] Preferably, along the horizontal axis of the absorption tank, a first window mirror and a second window mirror are respectively provided on both sides of the absorption tank, and the light from the light source passes through the first window mirror and the second window mirror and then through the filter medium in the absorption tank.

[0020] Preferably, an air inlet and an air outlet are respectively provided on both sides of the absorption pool along a direction perpendicular to the axis of the absorption pool. The filter medium is injected into the absorption pool through the air inlet and discharged from the absorption pool through the air outlet.

[0021] Preferably, the air inlet and air outlet are connected to a gas circulation device via gas pipelines, and the gas circulation device drives the filter medium to circulate through the absorption tank.

[0022] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0023] This invention innovatively integrates an absorption cell within a Heriot-Limited Multipass Cell. Through the synergistic effect of the first and second concave mirrors within this cell, the light source undergoes multiple reflections within the cell, significantly extending the optical path. Throughout the reflection process, the light source passes through the absorption cell, effectively multiplying the optical path length of the light source in the saturable absorption medium. Based on this, saturable absorption of small-signal noise light is achieved, effectively improving isolation and significantly increasing the absorption rate of small-signal noise light. Furthermore, the power loss of the main pulse is minimal each time the light source passes through the absorption cell. By precisely and rationally controlling the optical path and the pressure of the filter medium, the transmittance of the main pulse can be ensured to be no less than 95%.

[0024] Based on the beam reproduction law of the Heriot-Limiter multi-pass cell, the focal point of the beam formed by the reflection of the light source is stably maintained at the midpoint of the Z-axis of the Heriot-Limiter cell (i.e., the direction of the concave mirror normal), thus the beam is highly focused in the central region. This invention incorporates an absorption cell in this central region, ensuring the beam remains focused throughout its passage through the filter medium. This focusing significantly increases the peak power density, effectively reducing the insertion loss of the main pulse laser and further enhancing noise-optical isolation.

[0025] Given the reflective effect of the Heriot-Cell multipath, the original linear long-distance single-path structure is cleverly transformed into a short-distance multipath structure, achieving a significant increase in optical path within a limited space. This makes the noise optical isolator structure of the present invention more compact, significantly reduces its size and cost, and also has stronger applicability, meeting the application needs of various different scenarios.

[0026] The present invention also includes a gas circulation device, which can promote the circulation of the filter medium in the absorption tank. The circulation of the filter medium can further increase the isolation, accelerate the relaxation of the upper energy level, and stabilize the temperature of the filter medium. Attached Figure Description

[0027] Figure 1 This is a structural diagram of a noise optical isolator based on a Heriot-Limiter multi-pass cell according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the reflection of light from a light source in the Heriot-Turkey multipass pool according to an embodiment of the present invention;

[0029] Figure 3 This is a distribution diagram of reflection points on the first concave mirror (or the second concave mirror) in a simulation experiment provided according to an embodiment of the present invention;

[0030] Figure 4 This is a comparison diagram of the intensity of the incident main pulse and the incident small signal noise light provided according to an embodiment of the present invention;

[0031] Figure 5 This is a comparison diagram of the emitted main pulse and emitted small signal noise light intensity provided according to an embodiment of the present invention.

[0032] The reference numerals in the figures include:

[0033] Light source 1, light source beam 11, incident main pulse 12, incident small signal noise light 13, outgoing main pulse 14, outgoing small signal noise light 15, Heriot-Lewis multi-pass cell 2, first concave mirror 21, second concave mirror 22, light inlet 23, light outlet 24, reflection point 25, absorption cell 3, first window mirror 31, second window mirror 32, air inlet 33, air outlet 34, gas pipe 35, filter medium 4. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and do not constitute a limitation thereof. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the invention. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the invention are not shown or described in the specification. This is to avoid obscuring the core parts of the invention with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined to form various implementations. Furthermore, the order of the steps or actions in the method description can be changed or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a noise optical isolator based on a Heriot-Limited multipass cell, used to filter noise light contained in the light source 11. The noise optical isolator includes a light source 1, a Heriot-Limited multipass cell 2, an absorption cell 3, and a filter medium 4.

[0040] The light source 1 in this embodiment of the invention is a high-repetition-rate short-pulse carbon dioxide laser light source (e.g.) The laser (which can also be a laser of other wavelengths, such as a mid-wave laser, a 1µm or 2µm laser) consists of core modules such as a seed laser and a main amplifier. The seed laser can be an acousto-optic modulated carbon dioxide pulse clipping laser, an electro-optic cavity emptied carbon dioxide laser, or a quantum cascade laser, while the main amplifier can be a fast transverse flow carbon dioxide laser, a fast axial flow carbon dioxide laser, or a slab carbon dioxide laser.

[0041] In this embodiment of the invention, light source 1 operates in conjunction with a seed laser and a single-stage fast axial-current carbon dioxide amplifier. Except for power, the carbon dioxide laser pulses provided by light source 1 meet the requirements of the main pump carbon dioxide laser for LPP-EUV light sources. Specifically, the high-repetition-rate short-pulse carbon dioxide laser provided in this embodiment has a repetition frequency of 50kHz to 100kHz, a polarization state of linearly or circularly polarized light, a beam quality M² factor of less than 3, a pulse width on the order of 10ns to 50ns, an average power on the order of hundreds of watts to tens of thousands of watts, and a final output power of 1000W. It is worth noting that the amplified carbon dioxide laser may contain a small-signal noise component with a power of 10W or even higher, while the remaining portion is the required short-pulse carbon dioxide laser. The small-signal noise component can be generated by a MOPA laser containing all stages of amplifiers, or by a portion of the MOPA amplification stage. A noise isolator can isolate the small-signal noise component in the high-repetition-rate short-pulse carbon dioxide laser.

[0042] The Heriot-Limited Cell 2 includes two focusing mirrors, a first concave mirror 21 and a second concave mirror 22. The concave surfaces of the first concave mirror 21 and the second concave mirror 22 are arranged opposite each other, and the optical axes of the first concave mirror 21 and the second concave mirror 22 are coaxial. The focal points of the first concave mirror 21 and the second concave mirror 22 are collinear. The substrates of the first concave mirror 21 and the second concave mirror 22 can be materials such as silicon, copper, or gallium arsenide. A light inlet 23 is provided at the edge of the first concave mirror 21, and a light outlet 24 is provided at the edge of the second concave mirror 22. The light ray 11 emitted by the light source 1 (i.e., carbon dioxide laser in this embodiment of the invention) enters the Heriot-Limited Cell 2 through the light inlet 23 on the first concave mirror 21, and is repeatedly reflected between the first concave mirror 21 and the second concave mirror 22, and finally leaves the Heriot-Limited Cell 2 through the light outlet 24 on the second concave mirror 22. The light source 11 significantly increases the optical path length through a limited number of reflections, effectively shortening the long-distance single optical path, thereby reducing the size of the noise optical isolator and making its structure more compact. This embodiment of the invention significantly reduces the long-distance single optical path length to: ,in, Indicates the light transmission thickness, which is the effective optical path length of a linear noise optical isolator; that is, the length of a single optical path of the linear noise optical isolator for the same optical path distance. This indicates the number of reflections of light rays from the light source within the Heriot-Touch multi-path pool 2. The path length of the light ray 11 in the Heriot-Limited Cell 2 is the single-pass optical path of the light source 11, which is the length of the Heriot-Limited Cell 2.

[0043] like Figure 3As shown, during repeated reflections, the light source 11 forms multiple reflection points 25 on the first concave mirror 21 and the second concave mirror 22, and the reflection points 25 are distributed at equal intervals around the circumference. To ensure that the light source 11 stays in the Heriot-Limited Cell 2 for a sufficient amount of time and that the optical path is long enough, i.e., to ensure that the light source 11 does not leave the Heriot-Limited Cell 2 prematurely, in this embodiment of the invention, the diameters of the light inlet aperture 23 and the light outlet aperture 24 are both set to be smaller than the distance between any two adjacent reflection points on the first concave mirror 21 or the second concave mirror 22, so as to achieve the purpose of preventing the light source 11 from leaving the Heriot-Limited Cell 2 prematurely. Figure 3 Different colors in the diagram represent different incoherent irradiance levels.

[0044] In other embodiments of the invention, the Heriot-Cross Pool 2 can also be designed with other structures, such as a structure containing multiple concave mirrors.

[0045] To ensure the reflection effect of the first concave mirror 21 and the second concave mirror 22 on the carbon dioxide laser, this embodiment of the invention deposits a high-reflectivity film for the carbon dioxide laser on the surfaces of the first concave mirror 21 and the second concave mirror 22 to enhance the reflection of the carbon dioxide laser. If the light source 11 emitted by the light source 1 is another type of light, then a corresponding high-reflectivity film to enhance the reflection of the light source 11 is deposited on the surfaces of the first concave mirror 21 and the second concave mirror 22.

[0046] Absorption cell 3 has an approximately hexahedral structure and is made of materials such as stainless steel and aluminum alloy. The light transmittance of absorption cell 3 is... The light transmission thickness depends on the required isolation of the light source 11. The effective optical path of the linear noise isolator is minimal (the angle between the propagation direction of the light source 11 and the axis of the absorption cell 3 is extremely small). The absorption cell 3 is located between the first concave mirror 21 and the second concave mirror 22, with the optimal position being at the geometric center between the first concave mirror 21 and the second concave mirror 22. The absorption cell 3 can be vacuum-sealed with the filter medium 4, which is used to filter out small-signal noise light in the light source 11.

[0047] Along the horizontal axis of the absorption cell 3, a first window mirror 31 and a second window mirror 32 are respectively provided on the left and right sides of the absorption cell 3. The first window mirror 31 and the second window mirror 32 have high transmittance to the light source 11, and the projections of the first window mirror 31 and the second window mirror 32 overlap along the optical axis. Along the direction perpendicular to the axis of the absorption cell 3, an air inlet 33 and an air outlet 34 are respectively provided on both sides of the absorption cell 3. The filter medium 4 is injected into the absorption cell 3 through the air inlet 33 and discharged from the absorption cell 3 through the air outlet 34.

[0048] like Figure 4The diagram shows a comparison between the intensity of the main pulse light and the intensity of the small-signal noise light in the light source 11. The time-domain waveform of the main pulse is generally Gaussian, but it may also be a triangular wave or a Gaussian waveform containing a slab. The small-signal noise light is generated by the amplification of spontaneous emission light or by reflection at an uncontrolled reflection point in the MOPA system. It starts as a small signal and can form oscillations after exceeding a threshold. The light source 11 emitted by the light source 1 enters the Heriot-Limited Multipass Cell 2 through the light inlet 23 and is repeatedly reflected between the first concave mirror 21 and the second concave mirror 22. Since the absorption cell 3 is located between the first concave mirror 21 and the second concave mirror 22, and the first window mirror 31 and the second window mirror 32 are respectively provided on the left and right sides of the absorption cell 3, the light source 11 is repeatedly reflected inside the Heriot-Limited Multipass Cell 2. Each reflection passes through the first window mirror 31 and the second window mirror 32 and then through the absorption cell 3, that is, through the sealed filter medium 4 inside the absorption cell 3. The focal point of each reflection of the light source 11 is located at the center of the absorption cell 3, forming a focal plane, and the cross-section of the filter medium 4 covers the focal point of each reflection. For example... Figure 5 As shown, the contrast between the main pulse and the small-signal noise light is enhanced each time the repeatedly reflected light 11 passes through the filter medium 4. After propagation dozens of times, the transmittance of the main pulse and the small-signal noise light changes significantly. The small-signal noise light is efficiently suppressed and absorbed, and its intensity is greatly attenuated, thus achieving the function of noise light filtering. The Heriot-Lewis multi-pass cell 2 allows for multiple focusing of the light 11 within a limited space. Each focusing passes through the absorption cell 3, which is equivalent to the light 11 passing through the absorption cell 3 over a long distance with a very small spot, achieving efficient "screening" of the main pulse laser and the small-signal noise light, thus achieving efficient inter-pulse noise light filtering. The absorption cell 3 can also be other saturable absorbers, such as hot carbon dioxide gas or dyes, or other saturable absorbers in other wavelength bands.

[0049] The focal point of the light ray 11 after each reflection is located at the center of the absorption cell 3, forming the focal plane. Approximately:

[0050] ,

[0051] in, This indicates the focal length of Heriot-Turkey multi-path pool 2. This indicates the beam divergence angle of the light source 11 before it enters the Heriot multi-pass cell 2.

[0052] Average power density for:

[0053] .

[0054] After filtration by absorption cell 3, the transmittance of the main pulse of light from light source 11 is... for:

[0055] ,

[0056] small signal noise light transmittance for:

[0057] ,

[0058] in, express, express, express, Indicates the thickness of light transmission.

[0059] Because the main pulse power in light source 11 is significantly higher than that of small-signal noise light, according to the principle of saturable absorption, Significantly smaller than A significant difference exists in the transmittance between the main pulse and the small-signal noise light, with the small-signal noise light being significantly suppressed. Specifically, the transmittance of the main pulse of the light source 11... The transmittance of small-signal noise light is 0.9. With a value of 0.01, the contrast ratio between the two changes from 1000:1 to 900:0.1, and small signal noise light is significantly suppressed.

[0060] The sealed filter medium 4 inside the absorption tank 3 can be sulfur hexafluoride or a mixture of sulfur hexafluoride gases, such as sulfur hexafluoride mixed with helium or nitrogen. In this embodiment of the invention, sulfur hexafluoride is used as the filter medium 4.

[0061] To improve the noise and light filtering effect, this embodiment of the invention also provides a gas circulation device. The inlet 33 and outlet 34 are connected to the gas circulation device via gas pipes 35, respectively. The gas circulation device drives the filter medium 4 to circulate within the absorption tank 3. To further enhance the circulation effect of the filter medium 4, this embodiment of the invention also sets the inner wall of the absorption tank 3 at the edges of the first window mirror 31 and the second window mirror 32 to a low-pressure-drop streamline shape, and sets the connection between the gas pipe 35 and the inlet 33 and outlet 34 to a standard vacuum chuck interface such as KF, ISO, or CF, to reduce the resistance during the circulation of the filter medium 4. By setting up the gas circulation device, the filter medium 4 can be circulated within the absorption tank 3. The circulation of the filter medium 4 can further increase the isolation, accelerate the relaxation of the upper energy level, and stabilize the temperature of the filter medium 4.

[0062] To maintain the temperature of the filter medium 4, a heat exchanger or gas flow device can be added to the absorption tank 3, thereby maintaining the isolation and insertion loss stability of the absorption tank 3.

[0063] The embodiments of the present invention conducted simulation experiments on a noise optical isolator based on a Heriot-Limiter multi-pass cell, and obtained the following results: Figure 3 The distribution diagram of reflection points 25 on the first concave mirror (or the second concave mirror) shown is derived from... Figure 3 It can be seen that the reflection points 25 are distributed at equal intervals around the circumference on the first concave mirror (or the second concave mirror).

[0064] Light ray 11 emitted by light source 1 enters the Heriot-Limited Cell 2, containing an incident main pulse 12 and incident small-signal noise light 13, such as... Figure 4 As shown, the time-domain waveform of the incident main pulse 12 is generally Gaussian, but may also be a triangular wave or a Gaussian waveform containing a slab. The intensity of the incident small-signal noise light 13 is much lower than that of the incident main pulse 12. After being filtered by the noise light isolator, it exits from the Heriot-Lewis multipass cell 2. The exit light contains the exit main pulse 14 and the exit small-signal noise light 15, as shown in the figure. Figure 5 As shown, the intensity of the emitted main pulse 14 is partially lost, and the intensity of the emitted small signal noise light 15 is significantly attenuated.

[0065] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0066] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A Heriot multi-pass-cell based noise optical isolator for filtering noise light contained in light from a light source, characterized by, The application relates to a light source and a light source system. The light source light is repeatedly reflected in the Heriot multi-pass cell; the focal point of the light source light after each reflection is located at the middle position of the absorption cell and forms a focal plane. The absorption cell is located in the Heriot multi-pass cell, and the absorption cell is provided with the filter medium. The filter medium is used for filtering noise light in the light source light. The Heriot multi-pass cell comprises a first concave mirror and a second concave mirror, and the first concave mirror and the second concave mirror are coaxial; the light source light is repeatedly reflected between the first concave mirror and the second concave mirror.

2. The Heriot multi-pass-cell based noise optical isolator of claim 1, wherein, An entrance hole is arranged at the edge position of the first concave mirror, and an exit hole is arranged at the edge position of the second concave mirror; the light source light enters the Heriot multi-pass cell through the entrance hole and exits the Heriot multi-pass cell through the exit hole after repeated reflection.

3. The Héroniot multi-pass-cell based noise optical isolator as set forth in claim 2, wherein, The light source light repeatedly reflects to form a plurality of reflection points, and the diameters of the entrance hole and the exit hole are smaller than the distance between any two adjacent reflection points.

4. The Héroniot multi-pass-cell based noise optical isolator of claim 3, wherein, The surfaces of the first concave mirror and the second concave mirror are coated with high-reflection film for enhancing the reflection of the light source light.

5. The Héroniot multi-pass-cell based noise optical isolator as set forth in claim 2, wherein, The absorption cell is located at the geometric center between the first concave mirror and the second concave mirror.

6. The Héroniot multi-pass-cell based noise optical isolator as set forth in claim 2, wherein, First and second window mirrors are arranged at the two sides of the absorption cell along the horizontal axis direction of the absorption cell, and the light source light passes through the filter medium in the absorption cell through the first and second window mirrors.

7. The Heriot multi-pass-cell based noise optical isolator of claim 1, wherein, Air inlets and air outlets are arranged at the two sides of the absorption cell along the direction perpendicular to the axis of the absorption cell; the filter medium is injected into the absorption cell through the air inlets and discharged from the absorption cell through the air outlets.

8. The Heriot multi-pass-cell based noise optical isolator as described in claim 1, wherein, The air inlets and the air outlets are respectively connected with a gas circulation device through gas pipelines, and the gas circulation device drives the filter medium to circulate through the absorption cell.

9. The Héroniot multi-pass-cell based noise optical isolator as claimed in claim 8, wherein, ​

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