This application claims priority to Chinese Application No. 202210740285.7, filed on Jun. 27, 2022, the entire content of which is incorporated herein by reference.
The present disclosure relates to the laser technology field and, in particular, to an optical modulation device and a laser apparatus.
A laser device is a device that can emit laser. A pump source, a gain medium, and a resonator are three major functional members of the laser device. The pump source provides a light source for the laser device. The gain medium (i.e., working material) absorbs energy provided by the pump source and amplifies light. The resonant cavity is configured to select the light of certain modes for outputting.
The pump source is used as an energy source and is configured to generate photons to excite the gain medium. The photons emitted by the pump source pump particles in the gain medium from a ground state to a high energy level state to achieve population inversion. Excitation mechanisms include optical excitation (optical pumping), gas-discharging excitation, chemical excitation, and nuclear energy excitation. At present, a high-power semiconductor laser device (LD) is generally used as the pump source, which is mainly configured to complete the conversion from electric energy to optical energy. The gain medium is configured to achieve the population inversion, amplify light, and affect a wavelength of the output laser.
The gain medium can be liquid, gas, or solid. The liquid can be organic solution, the gas can be carbon dioxide, and the solid can be ruby. A fundamental requirement of the gain medium is that photons are generated after the gain medium is excited rather than a photothermal conversion. The particles need to be in a relatively isolated state to allow transition between energy levels. The resonant cavity mainly functions to “store” and “purify” the laser.
The resonant cavity is usually formed by two mirrors, or can be a ring-shaped resonant cavity formed by a coupler. Photons are reflected back and forth between the mirrors to continuously cause stimulated radiation in the gain medium to generate high-intensity laser. Meanwhile, the resonant cavity can make the photon in the cavity have the same frequency/wavelength, phase and propagation direction, and make the laser have good directivity and coherence.
The optical performance of the laser apparatus needs to be improved.
Embodiments of the present disclosure provide an optical modulation device, including a waveguide, a first electrode layer, and a second electrode layer. The waveguide layer includes a waveguide body and a plurality of nano-waveguides embedded in the waveguide body and extending in an extension direction. The first electrode layer is arranged on one side of the waveguide layer and includes a plurality of first electrodes extending along the extension direction and arranged in a one-to-one correspondence with the plurality of nano-waveguides. The second electrode layer is arranged on a side of the waveguide layer facing away from the first electrode layer and includes a plurality of second electrodes extending in the extension direction and arranged in a one-to-one correspondence with the plurality of first electrodes. Each of the plurality of second electrodes and a corresponding one of the plurality of first electrodes are configured to apply a modulation voltage to a corresponding one of the plurality of nano-waveguides to change a refractive index of the corresponding one of the plurality of nano-waveguide.
Embodiments of the present disclosure provide a laser apparatus, including a laser emitter and an optical modulation device. The optical modulation device is arranged on a light-emitting side of the laser emitter and includes a waveguide, a first electrode layer, and a second electrode layer. The waveguide layer includes a waveguide body and a plurality of nano-waveguides embedded in the waveguide body and extending in an extension direction. The first electrode layer is arranged on one side of the waveguide layer and includes a plurality of first electrodes extending along the extension direction and arranged in a one-to-one correspondence with the plurality of nano-waveguides. The second electrode layer is arranged on a side of the waveguide layer facing away from the first electrode layer and includes a plurality of second electrodes extending in the extension direction and arranged in a one-to-one correspondence with the plurality of first electrodes. Each of the plurality of second electrodes and a corresponding one of the plurality of first electrodes are configured to apply a modulation voltage to a corresponding one of the plurality of nano-waveguides to change a refractive index of the corresponding one of the plurality of nano-waveguides.
In the following, some example embodiments are described. As those skilled in the art would recognize, the described embodiments can be modified in various manners, all without departing from the spirit or scope of the present disclosure. Accordingly, the drawings and descriptions are illustrative in nature and not limiting.
In the present disclosure, terms such as “first,” “second,” and “third” can be used to describe various elements, components, regions, layers, and/or parts. However, these elements, components, regions, layers, and/or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or layer. Therefore, a first element, component, region, layer, or part discussed below can also be referred to as a second element, component, region, layer, or part, which does not constitute a departure from the teachings of the present disclosure.
A term specifying a relative spatial relationship, such as “below,” “beneath,” “lower,” “under,” “above,” or “higher,” can be used in the disclosure to describe the relationship of one or more elements or features relative to other one or more elements or features as illustrated in the drawings. These relative spatial terms are intended to also encompass different orientations of the device in use or operation in addition to the orientation shown in the drawings. For example, if the device in a drawing is turned over, an element described as “beneath,” “below,” or “under” another element or feature would then be “above” the other element or feature. Therefore, an example term such as “beneath” or “under” can encompass both above and below. Further, a term such as “before,” “in front of,” “after,” or “subsequently” can similarly be used, for example, to indicate the order in which light passes through the elements. A device can be oriented otherwise (e.g., being rotated by 90 degrees or being at another orientation) while the relative spatial terms used herein still apply. In addition, when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or there can be one or more intervening layers. In this disclosure, if a light beam encounters a first element and then reaches a second element, the second element is referred to as being downstream the first element or downstream the first element in an optical path, and correspondingly the first element is referred to as being upstream the second element or upstream the second element in the optical path.
Terminology used in the disclosure is for the purpose of describing the embodiments only and is not intended to limit the present disclosure. As used herein, the terms “a,” “an,” and “the” in the singular form are intended to also include the plural form, unless the context clearly indicates otherwise. Terms such as “comprising” and/or “including” specify the presence of stated features, entities, steps, operations, elements, and/or parts, but do not exclude the existence or addition of one or more other features, integers, steps, operations, elements, parts, and/or combinations thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the listed items. The phrases “at least one of A and B” and “at least one of A or B” mean only A, only B, or both A and B.
When an element or layer is referred to as being “on,” “connected to,” “coupled to,” or “adjacent to” another element or layer, the element or layer can be directly on, directly connected to, directly coupled to, or directly adjacent to the other element or layer, or there can be one or more intervening elements or layers. In contrast, when an element or layer is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “directly adjacent to” another element or layer, then there is no intervening element or layer. “On” or “directly on” should not be interpreted as requiring that one layer completely covers the underlying layer.
In the disclosure, description is made with reference to schematic illustrations of example embodiments (and intermediate structures). As such, changes of the illustrated shapes, for example, as a result of manufacturing techniques and/or tolerances, can be expected. Thus, embodiments of the present disclosure should not be interpreted as being limited to the specific shapes of regions illustrated in the drawings, but are to include deviations in shapes that result, for example, from manufacturing. Therefore, the regions illustrated in the drawings are schematic and their shapes are not intended to illustrate the actual shapes of the regions of the device and are not intended to limit the scope of the present disclosure.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this disclosure belongs. Terms such as those defined in commonly used dictionaries should be interpreted to have meanings consistent with their meanings in the relevant field and/or in the context of this disclosure, unless expressly defined otherwise herein.
As used herein, the term “substrate” can refer to the substrate of a diced wafer, or the substrate of an un-diced wafer. Similarly, the terms “chip” and “die” can be used interchangeably, unless such interchange would cause conflict. The term “layer” can include a thin film, and should not be interpreted to indicate a vertical or horizontal thickness, unless otherwise specified.
A semiconductor laser device, also known as a laser diode, is a laser device that uses a semiconductor material as a working material. The semiconductor laser device can be a practical type of laser device. The semiconductor laser device is small and has a long lifetime. The semiconductor can be pumped by being charged with current. An operating voltage and an operating current can be compatible with an integrated circuit. Thus, the semiconductor laser device can be suitable for monolithic integration. In addition, for a semiconductor laser device, current can be directly modulated with a frequency up to GHz to obtain a high-speed modulated laser output. Based on the advantages, the semiconductor laser device can be widely used in aspects such as laser communication, optical storage, optical gyro, laser printing, distance ranging, and radar.
In some embodiments, a metasurface device can be arranged at a light-emitting end surface of the semiconductor laser device. Thus, a shape and a direction of an emitted light beam can be modulated using the metasurface device. Metasurface refers to an artificial two-dimensional material with the sizes of basic structure units smaller than the working wavelengths. The basic structure unit can be a nanostructure unit with a size in the order of nanometers. Metasurface can realize flexible and effective control of the characteristics, such as propagation direction, polarization mode, amplitude, and phase, of electromagnetic waves. Metasurface can also have an ultra-light characteristic.
Embodiments of the present disclosure provide an optical modulation device and a laser apparatus to improve the optical performance of the laser apparatus.
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A specific material of the waveguide body 251 is not limited in embodiments of the present disclosure and can include, for example, at least one of silicon, silicon oxide, silicon nitride, gallium arsenide, aluminum gallium arsenide, or indium gallium arsenide. In addition, the waveguide body 251 can also be made of a gain medium material having an amplification effect on optical power, such as doped polycrystalline ceramic.
A width dimension of the nano-waveguide 252 can be smaller than the operating wavelength and in an order of sub-wavelength. In embodiments of the present disclosure, the nano-waveguide 252 can be made of an electro-optical material, which can generate an electro-optical effect. The electro-optic effect refers to that a refractive index of the electro-optical material changes when a voltage is applied to the electro-optical material, which causes a characteristic of a light wave passing through the electro-optical material to change. Through the electro-optical effect, a parameter of an optical signal, such as phase, amplitude, intensity, polarization, beam shape, etc., can be modulated. In embodiments of the present disclosure, the material of the nano-waveguide 252 can include at least one of a lithium niobate crystal, a gallium arsenide crystal, a lithium tantalate crystal, or a potassium dihydrogen phosphate crystal.
In embodiments of the present disclosure, when a modulation voltage is applied to the nano-waveguide 252 of the electro-optical material through the first electrode 241 and the second electrode 261, the refractive index of the nano-waveguide 252 can change as a signal of the modulation voltage changes. Refractive indexes of different nano-waveguides 252 can be flexibly adjusted according to a light-emitting requirement. Thus, the emitted light beam can be actively modulated. For example, deflection, phase, wavelength, intensity, polarization, and/or beam shape, etc., of the emitted light beam can be flexibly modulated. Compared to related technology, the optical performance of the laser apparatus consistent with the disclosure can be improved and expanded.
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In some embodiments of the present disclosure, the material of the first electrode layer 24 and the second electrode layer 26 can include at least one of indium tin oxide or indium zinc oxide. In addition, the material of the first wire layer 21 and the second wire layer 29 can also include at least one of indium tin oxide or indium zinc oxide. These materials are transparent and conductive, which can reduce the influence on the light transmission efficiency of the device as much as possible.
In some embodiments, the first wire layer 21 and the second wire layer 29 may also be made of an opaque conductive material, for example, including at least one of aluminum neodymium alloy, aluminum, copper, molybdenum tungsten alloy, or chromium.
The waveguide layer 25 can be prepared as a single layer or can be prepared as a plurality of layers one over another. The plurality of nano-waveguides 252 can be arranged in two dimensions in addition to one dimension. In some embodiments of the present disclosure, the plurality of nano-waveguides can also be arranged in a plurality of layers in the waveguide body. Each layer can include a plurality of nano-waveguides. The plurality of nano-waveguides arranged in the same layer can be arranged along the second direction crossing the first direction in sequence. At least two layers of nano-waveguides do not overlap with each other in a thickness direction. The second direction can be orthogonal to the first direction or have the determined angle with the first direction. With the nano-waveguides arranged in the plurality of layers, the nano-waveguides can achieve a more compact layout, and the modulation efficiency and modulation effect of the light can be enhanced.
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The laser emitter 10 and the optical modulation device 20 can be cascaded. Structures and electrodes of the laser emitter 10 and the optical modulation device 20 can be configured separately without interference. Since the optical modulation device 20 actively modulates the emitted light beam, the optical performance of the laser device 100 can be flexibly adjusted, expanded, and improved as needed to obtain relatively good optical performance.
Specific type of the laser emitter 10 is not limited. For example, the laser emitter can include a gas laser device, a solid-state laser device, a semiconductor laser device, or a dye laser device. In some embodiments, the laser emitter 10 can be a distributed feedback laser (DFB), with Bragg gratings arranged therein, which is a type of edge-emitting semiconductor laser device. The resonator of the laser emitter 10 can be, for example, a Fabry-Pérot cavity (F-P cavity), which can adjust and control the wavelength.
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The present specification provides many different embodiments or examples for implementing the present disclosure. These different embodiments or examples are exemplary and are not used to limit the scope of the present disclosure. Those skilled in the art can think of various modifications or replacements based on the disclosed content of the present disclosure. These modifications and replacements should be within the scope of the present disclosure. Thus, the scope of the present invention is subjected to the scope defined by the appended claims.
Number | Date | Country | Kind |
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202210740285.7 | Jun 2022 | CN | national |