Passive interference reduction in pockels cells

Abstract

To enable elimination of back-reflected acoustic waves.SOLUTION: A system and method is disclosed, for providing multi-material selection for elimination of back-reflected acoustic waves to produce acoustic compensation of an electro-optic modulator (EOM) for use in the Long-Wave Infrared (LWIR) spectrum and Mid-Wave Infrared (MWIR) spectrum.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and benefit of U.S. Provisional Patent Application No. 63 / 552,500, entitled "MULTI-MATERIAL SELECTION FOR ELIMINATION OF BACK-REFLECTED ACOUSTIC WAVES," filed February 12, 2024, which is hereby incorporated by reference in its entirety. [Background technology]

[0002]

[0002] The limitations and drawbacks of conventional systems and methods for reducing acoustic waves will become apparent to those skilled in the art upon comparing such approaches with certain aspects of the present methods and systems described in the remainder of this disclosure with reference to the drawings. Summary of the Invention

[0003]

[0003] The system and method provide multiple material options for eliminating back-reflected acoustic waves substantially as shown in and / or described in connection with at least one of the figures and more fully described in the claims. [Brief explanation of the drawings]

[0004] [Figure 1]

[0004] FIG. 1 illustrates an exemplary system having a matching layer operable to reduce the generation of back-reflected acoustic waves, according to various exemplary embodiments of the present disclosure. [Figure 2]

[0005] 1A-1C illustrate exemplary systems having stacks of matching layers operable to reduce the generation of back-reflected acoustic waves, in accordance with various exemplary embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0005]

[0007] The following description provides various examples of systems and methods for reducing the acoustic effects of Pockels cells. Such examples are non-limiting, and the scope of the appended claims should not be limited to the particular examples disclosed. In the following description, the terms "example" and "for example" are non-limiting.

[0006]

[0008] The figures show general schemes of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the present disclosure. Additionally, elements in the depicted figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of the examples discussed in this disclosure. The same reference numbers in different figures represent the same elements.

[0007]

[0009] The term "or" means any one or more of the items in the list connected by "or." As an example, "x or y" means any element of the three element set {(x),(y),(x,y)}. As another example, "x, y, or z" means any element of the seven element set {(x),(y),(z),(x,y),(x,z),(y,z),(x,y,z)}.

[0008]

[0010] The terms "comprises," "comprising," "includes," and / or "including" are "open-ended" terms that specify the presence of stated features but do not exclude the presence or addition of one or more other features.

[0009]

[0011] Terms such as "first," "second," and the like may be used herein to describe various elements, but these elements should not be limited by these terms. These terms are used only to distinguish one element from another. Thus, for example, a first element discussed in this disclosure could be referred to as a second element without departing from the teachings of the disclosure.

[0010]

[0012] Unless otherwise specified, the term "coupled" may be used to describe two elements that are in direct contact with each other or two elements that are indirectly connected by one or more other elements. For example, if element A is coupled to element B, element A may be in direct contact with element B or indirectly connected to element B by an intervening element C. Similarly, the terms "over" or "on" may be used to describe two elements that are in direct contact with each other or two elements that are indirectly connected by one or more other elements.

[0011]

[0013] Light is a fundamental phenomenon with diverse properties and applications that span the electromagnetic spectrum, from radio waves to gamma rays. While the human eye perceives only the visible spectrum, light extends beyond this range and includes longer wavelengths, such as infrared, and shorter wavelengths, such as ultraviolet and X-rays. These wavelength differences correspond to changes in energy, provide unique interactions with materials, and enable specialized technologies. For example, long-wave infrared (LWIR) light is characterized by lower energy and longer wavelengths compared to visible light and plays an important role in areas such as imaging, industrial processing, and advanced optics.

[0012]

[0014] An important attribute of light is its polarization, the orientation of its electric field in space. Polarization can appear as linear, circular, or elliptical, depending on the light wave's interaction with materials or filters. This property is particularly important when dealing with coherent light sources such as lasers, which propagate in a fixed direction and exhibit consistent wavelengths and polarizations. Being able to manipulate polarization can enable precise control over light for applications such as optical switching and modulation.

[0013]

[0015] The electro-optic effect, specifically the Pockels effect, is central to the operation of electro-optic modulators (EOMs), which enable dynamic control of light polarization. This effect occurs in certain non-centrosymmetric crystals; an applied electric field causes a change in the refractive index, altering the polarization state of the transmitted light. Materials such as cadmium telluride (CdTe), gallium arsenide (GaAs), zinc selenide (ZnSe), zinc sulfide (ZnS), and cadmium zinc telluride (CdZnTe or CZT), and boron arsenides (BAs), are among the few materials capable of supporting this effect in the LWIR and mid-wave infrared (MWIR) spectra due to their unique optical and structural properties.

[0014]

[0016] Pockels cells, the key component of EOMs, utilize these electro-optic materials to modulate light at high speeds without moving parts. By applying a voltage and / or electric field across the crystal, the birefringence of the material can be controlled, which can enable phase modulation of a laser beam with nanosecond precision. This capability is important in advanced applications such as extreme ultraviolet (EUV) lithography, where precise timing and modulation of light is essential to producing cutting-edge microchips.

[0015]

[0017] This disclosure relates to systems and methods for improving the performance of electro-optic modulators (EOMs) by mitigating unwanted acoustic effects. This disclosure addresses systems and methods for reducing acoustic wave reflections that degrade modulation efficiency, durability, and thermal handling capabilities.

[0016]

[0018] Electro-optic modulators are widely used in precision laser systems, such as those requiring high-power lasers and fast modulation frequencies. A key challenge in such systems is the generation of acoustic waves within the EOM crystal due to the coupling of piezoelectric and electro-optic effects. These acoustic waves can induce stress-induced birefringence, reducing the extinction ratio and overall efficiency of the system. This issue is particularly important in systems operating at certain resonant frequencies, where acoustic reflections magnify and exacerbate the performance degradation.

[0017]

[0019] A system and method for reducing or eliminating acoustic effects in EOMs is disclosed. The system includes impedance matching layers designed to reduce the generation of back-reflected acoustic waves. These layers can improve the modulation efficiency, durability, and thermal handling capabilities of EOM systems, thereby enabling improved performance across a wide range of fundamental frequencies from 1 kHz to 450 kHz, as well as their various resonant modes and beat frequencies.

[0018]

[0020] The disclosed system utilizes impedance-matching materials, optimized layer thicknesses, and advanced bonding techniques to minimize acoustic reflections, which enables modulation control while maintaining the integrity of high-power laser operation.

[0019]

[0021] FIG. 1 illustrates an example system with a matching layer operable to reduce the generation of back-reflected acoustic waves, according to various example embodiments of the present disclosure.

[0022] 1 shows an example of an acoustic attenuation system in an EOM, which includes a source material 101, a load material 105, and a matching layer 103.

[0020]

[0023] The source material 101 is the origin of the acoustic wave (e.g., an EOM crystal). The matching layer 103 can optimize the transfer energy between the first material 101 and the load material 105.

[0021]

[0024] To maximize acoustic wave transmission and minimize reflection, the impedance of the matching layer 103 is:

[0022]

number

[0023] where Z1 = impedance of the source material 101, Z2 = impedance of the load material 105, and Z m = the impedance of the matching layer material 103 through which the acoustic waves can be transmitted.

[0024]

[0025] The thickness of the matching layer 103 can be an integer multiple of a quarter wavelength of the source signal so that the reflections interfere destructively.

[0025]

number

[0026] where f=frequency of the propagating sound, and c=speed of sound in the load material 105. The characteristic specific acoustic impedance is Z=ρ*c Equation 3 where ρ=density, and c=speed of sound in the load material 105.

[0027] The back reflected wave can be calculated as the reflection from the source material 101 to the load material 105 due to the impedance mismatch.

[0028]

number

[0029]

[0028] The transmittance is

[0030]

number

[0031] It can be calculated as: The magnitude of the back reflected wave can be determined according to the impedance mismatch. FIG. 2 illustrates an example system having a stack of matching layers operable to reduce the generation of back-reflected acoustic waves, according to various example embodiments of the present disclosure.

[0032]

[0031] Figure 2 shows a stack of multiple matching layers 201, 203, 205 designed to handle more complex impedance mismatches. The ideal acoustic impedance of each layer (1, 2...n) in an n-layer stack is

[0033]

number

[0034] where Z1 = impedance of material 1 101, Z2 = impedance of material 2 105, and Z layer = the impedance of the damping material 201, 203, 205 in the layers (1, 2...n) through which the acoustic waves can be transported.

[0035] The materials of the matching layers 201, 203, and 205 can be selected according to impedance, density, and bonding compatibility. The impedance of the matching layers 201, 203, and 205 is selected to match the adjacent layers to minimize reflections. High-density materials can reduce the magnitude of back-reflected waves.

[0036]

[0033] Bonding compatibility of materials is considered to construct strong, thin bonds to facilitate acoustic wave transmission. Preferred bonding methods include optical contact, solid-state diffusion bonding, eutectic bonding, brazing, and / or adhesive bonding. Metals, metal oxides, and alloys such as stainless steel, brass, copper, tin, and titanium may be used for the matching layers 201, 203, and 205 due to their favorable properties. The matching layers 201, 203, and 205 may further include phase-change materials, thixotropic materials, and / or non-Newtonian materials. The bonding layers may also be configured for acoustic matching.

[0037] The disclosed system can be optimized for a wide range of frequencies, particularly between 40 kHz and 450 kHz, with best performance at, for example, 50 kHz. Frequencies above 450 kHz can introduce new challenges due to the limited propagation time of acoustic waves.

[0038] The disclosed system can accommodate high power laser operation by addressing thermal effects through material selection and structural optimization. Two common materials used for EOM crystals include cadmium telluride and gallium arsenide.

[0039] The disclosed system and method can improve modulation efficiency. The system can mitigate stress-induced birefringence by minimizing acoustic reflections. The disclosed systems and methods can improve durability, for example, reducing mechanical stress can extend the operational life of the EOM.

[0040] The disclosed systems and methods can accommodate a wide fundamental frequency range (eg, 1 kHz to 450 kHz), allowing versatility across applications. The disclosed systems and methods can provide thermal stability. Effective thermal management can support high-power laser operation without degradation. Matching layers can be configured for real-time tuning.

[0041] The disclosed system represents an advancement in EOM design and operation, addressing significant challenges posed by acoustic effects. By utilizing impedance matching layers, optimized materials, and precision bonding techniques, the system can enable high performance, durability, and adaptability over a wide range of frequencies and applications.

[0042]

[0041] Although the present method and / or system has been described with reference to specific embodiments, it will be understood by those skilled in the art that various modifications may be made and equivalents may be substituted without departing from the scope of the present method and / or system. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from its scope. Therefore, it is not intended that the present method and / or system be limited to the particular embodiments disclosed, but rather that the present method and / or system be intended to include all embodiments falling within the scope of the appended claims.

Claims

1. a non-centrosymmetric crystal; A load material; a matching layer operable to reduce the generation of back-reflected acoustic waves; Including, the acoustic impedance of the matching layer is determined according to the square root of the product of the impedance of the non-centrosymmetric crystal and the impedance of the load material; system.

2. The system of claim 1 , wherein the matching layer comprises a composite material configured for thermal stability.

3. 10. The system of claim 1, comprising multiple matching layers.

4. 10. The system of claim 1, wherein the non-centrosymmetric crystal supports long-wave infrared (LWIR) wavelengths.

5. 10. The system of claim 1, wherein the non-centrosymmetric crystal supports mid-wave infrared (MWIR) wavelengths.

6. 10. The system of claim 1 configured for integration into an optical application.

7. The system of claim 1 , wherein the matching layer comprises a metal oxide.

8. 10. The system of claim 1 configured to damp mechanical vibrations.

9. The system of claim 1 , wherein the matching layer comprises at least one of a phase change material, a thixotropic material, and a non-Newtonian material.

10. 10. The system of claim 1, wherein the matching layer is configured for real-time adjustment.

11. disposing a matching layer between a non-centrosymmetric crystal and a load material, the impedance of the non-centrosymmetric crystal being different from the impedance of the load material; determining a thickness of the matching layer as an integer multiple of a quarter wavelength of an acoustic wave; reducing the generation of back-reflected acoustic waves by the matching layer; A method comprising:

12. The method of claim 11 , wherein the matching layer comprises a composite material configured for thermal stability.

13. The method of claim 11 , wherein the matching layer comprises multiple layers of material.

14. 12. The method of claim 11, wherein the non-centrosymmetric crystal supports long-wave infrared (LWIR) wavelengths.

15. 12. The method of claim 11, wherein the non-centrosymmetric crystal supports mid-wave infrared (MWIR) wavelengths.

16. 12. The method of claim 11, wherein the non-centrosymmetric crystal, the matching layer, and the load material are configured for integration into an optical system.

17. The method of claim 11 , wherein the matching layer comprises a metal oxide.

18. The method of claim 11 , wherein the matching layer is configured to damp mechanical vibrations.

19. 12. The method of claim 11, wherein the matching layer comprises at least one of a phase change material, a thixotropic material, and a non-Newtonian material.

20. 12. The method of claim 11, wherein the matching layer is configured for real-time adjustment.

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