Integrated Photonic Quantum Vector Magnetometer

Abstract

The present invention is titled "Integrated Photonic Quantum Vector Magnetometer". Systems and methods for an integrated photonic quantum vector magnetometer are provided herein. In certain embodiments, a device includes: a substrate; a radio frequency transmitter that emits energy in a radio frequency range; and a waveguide layer formed on the substrate. The waveguide layer includes: a first waveguide of a first material in which a probe laser propagates; and a second waveguide that is positioned along a coupling length adjacent to the first waveguide such that a pump laser propagating in the second waveguide is coupled into the first waveguide along the coupling length, wherein the pump laser causes the first material to absorb the probe laser at one or more frequencies in a frequency range. Additionally, the device includes a processing device that calculates a magnetic field strength based on the identification of one or more frequencies.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 912,533, filed on October 8, 2019, and titled "INTEGRATED PHOTONICS QUANTUM VECTOR MAGNETOMETER", which is hereby incorporated by reference in its entirety.

[0003] This application is related to U.S. Non - Provisional Application No. 16 / 786,495, filed on February 10, 2020, and titled "QUANTUM VECTOR MAGNETOMETER BASED ON NANOSCALE FIN WAVEGUIDE", which is hereby incorporated by reference in its entirety. Background of the Invention

[0004] Many applications use precise measurements of magnetic fields. Specifically, applications attempt to measure vector magnetic fields to provide desired functionality within a system. For example, applications can measure magnetic fields in anomaly - based navigation and dipole - beacon - based navigation. These applications typically require a magnetic sensor with the following characteristics: high sensitivity; low size, weight, and power; and the ability to operate in the Earth's field. Some technologies (i.e., SQUIDs, atomic - based magnetometry) are capable of providing high sensitivity that can be used for certain applications. However, some of these technologies have drawbacks. For example, SQUIDs use cryogenic cooling, which increases the size and power consumption of the magnetometer. In addition, atomic - based magnetometers are not able to operate in the Earth's field. Additionally, the aforementioned technologies use at least three sensors to provide vector information. Summary of the Invention

[0005] Systems and methods for an integrated photonic quantum vector magnetometer are provided herein. In certain embodiments, the device includes a substrate. Additionally, the device includes a radio - frequency transmitter that emits energy in the radio - frequency range. Additionally, the device includes a waveguide layer formed on the substrate. The waveguide layer includes a first waveguide of a first material, where a probe laser propagates within the first waveguide. Additionally, the waveguide layer includes a second waveguide, where the second waveguide is positioned adjacent to the first waveguide along a coupling length such that a pump laser propagating within the second waveguide is coupled into the first waveguide along the coupling length, where the pump laser causes the first material to absorb the probe laser at one or more frequencies within a frequency range. Further, the device includes a processing device that calculates a magnetic field strength based on the identification of one or more frequencies. Brief Description of the Drawings

[0006] It should be understood that the drawings only show some embodiments and should not be considered as limiting the scope. The drawings will be used to describe the exemplary embodiments with additional features and details. In the drawings:

[0007] Figure 1 is a diagram showing the transitions between various states of a specific material for manufacturing a magnetometer according to one aspect of the present disclosure;

[0008] Figure 2 is a graph showing magnetic field detection based on the identification of resonance lines in an applied microwave field according to one aspect of the present disclosure;

[0009] Figure 3 is a diagram showing a waveguide structure that can be used to detect a magnetic field according to one aspect of the present disclosure;

[0010] Figure 4 is a graph showing the effect of different separation distances between waveguides in a waveguide structure for detecting a magnetic field according to one aspect of the present disclosure;

[0011] Figure 5 is a cross-sectional view showing the positions of different waveguides relative to each other in a waveguide structure for detecting a magnetic field according to one aspect of the present disclosure;

[0012] Figure 6 is a graph showing the intensity of light across the waveguide length in a waveguide for detecting a magnetic field according to one aspect of the present disclosure;

[0013] Figure 7 is a graph showing the power of light in a waveguide for different waveguide widths in a waveguide structure for detecting a magnetic field according to one aspect of the present disclosure;

[0014] Figure 8 is a graph showing the varying width of a waveguide along the waveguide coupling length in a waveguide structure for detecting a magnetic field according to one aspect of the present disclosure;

[0015] Figure 9 is a diagram of a waveguide system for detecting a magnetic field according to one aspect of the present disclosure; and

[0016] Figure 10 is a flowchart of a method for manufacturing a waveguide structure for detecting a magnetic field according to one aspect of the present disclosure.

[0017] By convention, the various features described are not necessarily drawn to scale but are used to emphasize specific features relevant to the exemplary embodiments. Detailed Description

[0018] In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific exemplary embodiments. However, it is to be understood that other embodiments may be utilized and logical, mechanical, and electrical changes may be made.

[0019] Methods and systems for an integrated photonic quantum vector magnetometer are provided herein. Specifically, the magnetometer can be fabricated as a parallel waveguide structure having a first waveguide of a first material and a second waveguide of a second material. A pump laser can be introduced into the second waveguide, where the pump laser is coupled from the second waveguide into the first waveguide along the lengths thereof that are parallel to each other. Additionally, a probe laser can be introduced into the first waveguide in the presence of a microwave signal. Then, the probe laser can be absorbed by the material of the first waveguide at a particular frequency of the microwave signal. Additionally, the system can determine a magnetic vector based on the frequency at which the material of the first waveguide absorbs the probe laser.

[0020] Figure 1 is a diagram showing transitions between various states of a particular material for fabricating a magnetometer. For example, some materials can have certain physical properties that allow the material to respond to a magnetic field. Examples of materials that respond to a magnetic field can include nitrogen-vacancy (NV) diamond, silicon carbide, or other materials having similar physical properties. As used herein, NV diamond can refer to a diamond material having multiple point defects, where the point defect is a nearest neighbor pair of a nitrogen atom substituting for a carbon atom and a lattice vacancy. The first waveguide can be made of a material that responds to a magnetic field.

[0021] As shown, an exemplary material that responds to a magnetic field can have a ground state that is a spin triplet. Specifically, the ground state can have multiple spin projections: a ground anti-parallel spin 101 of spin projection 0 and a ground parallel spin 103 of spin projection about + / -1, where the ground anti-parallel spin 101 and the ground parallel spin 103 are separated by a resonance frequency 121. For example, in the absence of a magnetic field, when the material is NV diamond, the resonance frequency 121 can be equal to 2.87 GHz. Additionally, point defects within the material can be optically excited to a spin triplet excited level by a spin-conserving transition, where the triplet excited level also has multiple spin projections: an excited anti-parallel spin 105 of spin projection 0 and an excited parallel spin 107 of spin projection about + / -1. To optically excite the point defects, the first material can be exposed to pump light having a particular frequency. For example, in NV diamond, a laser having a wavelength of 532 nm can cause a spin-conserving transition from the ground triplet to the excited triplet.

[0022] When a point defect within a first material is in an excited state, the defect can relax either by radiative transition 115 or by intersystem crossing 117. When the point defect relaxes by radiative transition 115, the point defect can fluoresce and return to the ground triplet state. For example, an NV diamond point defect can emit light with a wavelength of 637 nm during radiative transition 115. In contrast, when the point defect relaxes by intersystem crossing 117, the point defect will not fluoresce and will transition to a shelved state, where the shelved state can be a shelved ground state 111 or a shelved excited state 109. Additionally, when the point defect is in one of the shelved states 109 and 111, the point defect can absorb a probe laser 119 having a specific frequency. For example, an NV diamond point defect in shelved states 109 and 111 can absorb a probe laser 119 with a wavelength of 1042 nm.

[0023] In some embodiments, a microwave frequency can be applied to the material to increase the rate of intersystem crossing 117 compared to radiative transition 115. In the material, non-radiative intersystem crossing 117 can be strongly spin-selective. For example, point defects with parallel spins 107 are more likely to undergo intersystem crossing 117 to reach shelved states 109 and 111. In contrast, point defects with excited anti-parallel spins 105 are more likely to undergo a radiative transition back to the ground triplet state. To increase the probability of intersystem crossing, a microwave frequency equal to the resonant frequency 121 of the material can be applied to the material. For example, when the material is NV diamond, the resonant frequency 121 can be 2.87 GHz. Thus, applying a radio frequency of 2.87 GHz to the material can increase the probability of intersystem crossing 117 to shelved states 109 and 111.

[0024] Additionally, when a microwave signal at the resonant frequency 121 is applied to the material, the probe laser 119 is more likely to be absorbed by the material because the population of point defects in shelved states 109 and 111 within the material is greater than the population of point defects when the material is not exposed to RF energy at the resonant frequency 121. Thus, when the probe laser 119 is applied to the material in the absence of a microwave signal at the resonant frequency, the probe laser 119 is absorbed by the material with a lower frequency. For example, when an NV diamond material is exposed to a microwave signal with a resonant frequency 121 of 2.87 GHz, the NV diamond material can begin to absorb a probe laser 119 with a wavelength of 1042 nm at an increased rate.

[0025] In additional embodiments, the resonant frequency 121 of the material can be changed in the presence of a magnetic field. For example, when the material is exposed to a magnetic field, the Zeeman effect can cause the resonant frequency to undergo a shift that is proportional to the strength of the magnetic field experienced. Specifically, in the presence of a magnetic field, the resonant frequency 121 can split into two different resonant frequencies 121, where the difference between the two resonant frequencies 121 is proportional to the magnetic field experienced. Thus, the resonant frequency 121 at which point defects in the material absorb the probe laser 119 can be monitored to determine the strength of the magnetic field experienced by the material.

[0026] Additionally, the point defects within the material can be in one of a plurality of different orientations. For example, when the material is NV diamond, each point defect can be in one of four different orientations. Additionally, the material can have many point defects in each of the four different orientations. Thus, when the probe laser 119 is applied to the first material, vector information about the magnetic field can be extracted from the first material. For example, when the material is exposed to a magnetic field, the resonant frequency 121 of the point defects can shift based on the orientation of the point defects relative to the magnetic field experienced. Thus, when the point defects in the material are in a plurality of different orientations, the point defects in the material can have individual resonant frequencies associated with each of the different orientations of the point defects. Thus, the vector information about the magnetic field can be determined by identifying which resonances correspond to the different orientations of the point defects in the material. In some specific implementations, a bias magnetic field can be applied to the material to assist in determining which resonant frequencies are associated with a particular orientation of the point defects.

[0027] In the embodiments described herein, the material can be incorporated within a magnetometer that exposes the material to pump light 113 to cause point defects within the material to move to an excited triplet state. The magnetometer can also expose the first material to RF energy within a frequency range that includes the resonant frequency 121 of the first material, where the probability of intersystem crossing 117 to the shelving states 109 and 111 increases at the resonant frequency 121, as described above. Additionally, the material can be exposed to the probe laser 119, where the probe laser 119 is absorbed by the point defects in the shelving states 109 and 111. Thus, the applied microwave signal can be swept through a range of frequencies to identify the resonant frequencies 121 associated with the different orientations of the point defects within the material. The resonant frequencies 121 can be identified when the intensity of the applied probe laser 119 passing through the material decreases (thus indicating that the applied probe laser 119 is being absorbed by the point defects within the material). Based on the identified resonant frequencies 121, the magnetic field experienced by the material can be calculated by: high sensitivity to magnetic field changes; low size, weight, and power; and robustness that enables the resulting magnetometer to be used in many magnetically / auxiliary-based applications such as in navigation.

[0028] Figure 2It is a graph showing magnetic field detection based on the identification of resonance lines in an applied microwave field that sweeps through a series of frequencies. As described above, the material can be exposed to a series of microwave frequencies, where the applied frequency range includes different resonance frequencies of the material. Additionally, different resonance frequencies are associated with the strength of the magnetic field experienced by the material. Further, a first material can have different resonance frequencies associated with different orientations of point defects within the material.

[0029] As shown in the figure, Figure 2 It shows various graphs of the intensity of the probe laser emitted from the material at different microwave frequencies applied to the first material for three different magnetic field strengths. For example, graph 201 shows the intensity of the emitted probe laser at different frequencies when the material is not exposed to a magnetic field. When the probe laser is introduced into the material in the absence of an applied magnetic field, the material may not experience a Zeeman shift, and the probe laser can be absorbed at the single resonance frequency of the material. Thus, the intensity of light 201 can decrease at the single resonance frequency of the material.

[0030] Additionally, when the material is exposed to different magnetic field strengths, the resonance frequency can undergo a frequency shift that is proportional to the magnetic field strength experienced. For example, graphs 205 and 203 show the intensity of the probe laser emitted by the material in the presence of different magnetic field strengths. For example, the magnetic field strength experienced by the material associated with graph 203 is greater than the magnetic field strength experienced by the material associated with graph 205. Thus, when the material is exposed to a greater magnetic field strength, the magnitude of the shift in the resonance frequency is greater. To identify the magnitude of the shift in the resonance frequency, the system can identify the frequency 207 associated with a decrease in the intensity of the probe laser emitted by the material. Based on the magnitude of the shift in the resonance frequency, the system can determine the magnetic field experienced by the point defect. Additionally, when there are multiple resonance frequencies, the system can identify the orientation of the point defect associated with different resonance frequencies and the direction of the magnetic field experienced.

[0031] Figure 3 It is a diagram showing a waveguide structure 300 that can be used within a system for detecting a magnetic field. As shown, the waveguide structure can include a substrate 311. The substrate 311 can be made of any material capable of supporting the fabrication of additional layers thereon. For example, the substrate 311 can be a silicon substrate. Additionally, the substrate 311 can have a waveguide layer 301, where the waveguide layer 301 has a first waveguide 303 and a second waveguide 305 formed therein. In certain embodiments, the waveguide layer 301 can be made of silicon oxide, however, the waveguide layer 301 can be made of other materials with similar properties.

[0032] In certain embodiments, the first waveguide 303 can be made of a first material that is substantially similar to that described above in connection with Figure 1 and Figure 2The described material, and the second waveguide 305 can be made of a second material. For example, the first waveguide 303 can be made of NV diamond, and the second waveguide 305 can be made of nitride or other similar materials. To fabricate the first waveguide 303, a portion of the waveguide layer 301 can be fabricated on the substrate 311. When fabricating this portion of the waveguide layer 301, the first material can be deposited on this portion of the waveguide layer 301 in the region associated with the first waveguide 303. When depositing the first material, an additional portion of the waveguide layer 301 can be fabricated above the first waveguide 303. When fabricating the additional portion of the waveguide layer 301, the second material can be deposited on the additional portion of the waveguide layer 301 in the region associated with the second waveguide 305. When the second material has been deposited, the remaining portion of the waveguide layer 301 can be fabricated. The substrate 311, the waveguide layer 301, the first waveguide 303, and the second waveguide 305 can be fabricated using a process such as chemical vapor deposition or other methods suitable for fabricating the respective layers of the waveguide structure 300. As shown, the first waveguide 303 is fabricated before the second waveguide 305. It can be appreciated that the second waveguide 305 can be fabricated relative to the first waveguide 303 at any time as long as the position of the second waveguide 305 relative to the first waveguide 303 (as described below) is maintained.

[0033] In some embodiments, the first waveguide 303 and the second waveguide 305 can be fabricated parallel to each other such that light propagating through the second waveguide 305 is coupled into the first waveguide 303. For example, the pump laser 307 can be introduced into the second waveguide 305, which is coupled from the second waveguide 305 into the first waveguide 303. In some specific implementations, the pump laser 307 can be at the frequency of the pump light 119 described above in connection with Figure 1 the pump light 119. For example, when the first waveguide 303 is an NV diamond waveguide, the pump laser 307 can be a laser with a wavelength of 532 nm. Thus, when the pump laser 307 is coupled from the second waveguide 305 into the first waveguide 303, the pump laser 307 can cause point defects within the first waveguide 303 to transition to an excited triplet state.

[0034] In some embodiments, the physical relationship between the second waveguide 305 and the first waveguide 303 is changed such that the pump laser 307 is gradually coupled from the second waveguide 305 into the first waveguide 303. In some embodiments, the physical relationship between the second waveguide 305 and the first waveguide 303 is changed such that the pump laser 307 is gradually coupled into the first waveguide 303 along the coupling length where the first waveguide 303 and the second waveguide 305 are close to each other. Additionally, in some specific implementations, the pump laser 307 is substantially coupled into the first waveguide 303 such that the pump laser 307 no longer propagates in the second waveguide 305 after the coupling length of the first waveguide 303 and the second waveguide 305. By gradually coupling the pump laser 307 from the second waveguide 305 into the first waveguide 303, the amount of point defects transformed into excited triplets in the first waveguide 303 increases.

[0035] In certain embodiments, the probe laser 309 can be introduced from a laser source into the first waveguide 303. The probe laser 309 can have a wavelength that is absorbed by the point defects in the shelving state within the first material. For example, when the first waveguide 303 is made of NV diamond, the probe laser 309 can have a wavelength of 1042 nm.

[0036] When the waveguide structure 300 is exposed to a signal having the resonant frequency of the first material, the pump laser 307 coupled from the second waveguide 305 into the first waveguide 303 can cause the point defects within the first waveguide 303 to move to the shelving state. When the pump laser 307 is gradually coupled into the first waveguide 303 along the coupling length between the first waveguide 303 and the second waveguide 305, in the presence of a signal having the resonant frequency of the first material, the point defects can absorb the probe laser 309 along the coupling length. Additionally, since the resonant frequency of the first material changes when exposed to a magnetic field, the frequency of the applied signal can be changed to identify the frequency at which the point defects within the first waveguide 303 absorb the probe laser 309. As described above, different identified frequencies can be identified to determine the magnitude and direction of the magnetic field.

[0037] As Figure 3 discussed, the use of the waveguide increases the interaction length of light within the first material. As discussed above, when using the parallel first waveguide 303 and second waveguide 305, the pump laser 307 can be slowly coupled into the first waveguide 303, which serves as the probe waveguide in which the probe laser 309 propagates. The slow coupling of the pump laser 307 into the first waveguide 303 can be used because the rate at which the first material absorbs the pump laser 307 can be faster than the rate at which the first material absorbs the probe laser 309. For example, NV diamond absorbs the pump laser 307 about 10 times faster than it absorbs the probe laser 309.

[0038] If both the pump laser 307 and the probe laser 309 are introduced into the first waveguide 303 (instead of slowly coupling the pump laser 307 into the first waveguide 303 using the second waveguide 305), the length of the first waveguide 303 can be increased to allow absorption of the probe laser 309, thus for better comparison of the absorption of the probe laser 309 at various signal frequencies. However, the pump laser 307 will be absorbed in the first 10% of the length of the first waveguide 303. Therefore, the probe laser 309 will not be able to utilize the increased length of the first waveguide 303. Conversely, if the first waveguide 303 is short (i.e., the absorption length of the pump laser 307), the probe laser 309 will be absorbed over a short distance, but there is a lack of comparison of the absorption of the probe laser 309 at various applied signal frequencies. Therefore, due to the reduced comparison, the resulting measurement values will have lower accuracy.

[0039] Therefore, by slowly leaking the pump laser 307 into the first waveguide 303, the waveguide can provide increased absorption of the probe laser 309 along a shorter length of the first waveguide 303, resulting in greater contrast and efficient absorption of the pump laser 307 along the coupling length between the first waveguide 303 and the second waveguide 305. As described below, light can be slowly coupled from the second waveguide 305 to the first waveguide 303 in such a way that the pump laser 307 has a substantially constant intensity along the entire coupling length of the first waveguide 303 within the first waveguide 303.

[0040] Figure 4 is a graph showing the effect of different separation distances between waveguides in a waveguide structure (such as Figure 3 the waveguide structure 300 therein) for detecting a magnetic field. As shown, various coupling coefficients are shown for various widths of the second waveguide 305 made of a second material. For example, graph 401 shows the coupling coefficient of two coupled waveguides separated by 400 nm, graph 403 shows the coupling coefficient of two coupled waveguides separated by 500 nm; and graph 405 shows the coupling coefficient of two coupled waveguides separated by 600 nm. As shown, the rate at which light is coupled from the second waveguide 305 to the first waveguide 303 along the coupling length of the waveguide structure 300 depends on both the distance between the first waveguide 303 and the second waveguide 305 and the relative relationship between the width of the second waveguide 305 and the width of the first waveguide 303. Therefore, in order to control the rate at which light is coupled from the second waveguide 305 to the first waveguide 303 along the coupling length of the waveguide structure, one or both of the distance between the first waveguide 303 and the second waveguide 305 and the relative relationship between the width of the second waveguide 305 and the width of the first waveguide 303 can be varied along the coupling length.

[0041] Figure 5 is a graph showing as described above in Figure 3A cross-sectional view of an exemplary positioning of the first waveguide 303 within the waveguide layer 301 described relative to the second waveguide 305. As shown, the second waveguide 305 may be positioned above the first waveguide 303. Alternatively, the first waveguide 303 may be positioned above the second waveguide 305. Additionally, the first waveguide 303 and the second waveguide 305 may be positioned side by side.

[0042] Figure 6 Is a graph 600 showing the intensity of the pump laser 307 across the coupling length between the second waveguide 305 and the first waveguide 303 within the waveguide layer 301. As shown, the left side of the graph 600 shows the start of the coupling length, and the right side of the graph shows the end of the coupling length. As shown, when light is coupled into the first waveguide 303 as described above, the intensity of the pump laser 307 within the second waveguide 305 gradually decreases across the coupling length. Additionally, the intensity of the pump laser 307 within the first waveguide 303 may remain constant because when light is coupled from the second waveguide 305 into the first waveguide 303 due to the physical relationship between the first waveguide 303 and the second waveguide 305, the light of the pump laser 307 can be linearly absorbed by the material of the first waveguide 303.

[0043] Figure 7 Is a graph showing the power of the pump laser 307 propagating across the coupling length within the second waveguide 305 for different waveguide shapes. For example, graph 703 shows the power of the pump laser 307 within the second waveguide 305 when the shape of the second waveguide 305 (relative to the shape of the first waveguide 303) and the distance between the second waveguide 305 and the first waveguide 303 are constant across the entire coupling length. As shown in graph 703, light is coupled from the second waveguide 305 into the first waveguide 303 with a constant attenuation coefficient. In contrast, graph 701 shows the power of the pump laser 307 within the second waveguide 305 when the shape of the second waveguide 305 (relative to the shape of the first waveguide 303) and the distance between the second waveguide 305 and the first waveguide 303 vary such that the power of the pump laser 307 within the second waveguide 305 decreases linearly. When the power decreases linearly, the pump laser 307 may be coupled into the first waveguide 303 at a linear rate, and point defects within the first waveguide 303 may also linearly absorb the probe laser 309 along the coupling length. When the probe laser 309 is linearly absorbed, the sensitivity of the first waveguide 303 to the magnetic field may be consistent along the coupling length of the first waveguide 303.

[0044] Figure 8is a graph showing the varying width of the second waveguide 305 along the coupling length of the second waveguide 305. As shown, the width of the second waveguide 305 can decrease along the coupling length of the first waveguide 303 and the second waveguide 305. For example, the width of the second waveguide 305 can decrease over the coupling length such that the pump laser 307 is linearly coupled into the first waveguide 305, as shown in the graph 701.

[0045] Figure 9 is a diagram of a waveguide system that can be used to detect a magnetic field. As shown, the waveguide system 900 can include a first waveguide 903 and a second waveguide 905, which operate in a similar manner as described above with respect to the first waveguide 303 and the second waveguide 305, respectively. The waveguide system 900 can include an absorption region 901. As used herein, the absorption region 901 can refer to a region within the waveguide system 900 where the first waveguide 903 and the second waveguide 905 extend close to each other through a coupling length such that the pump laser 907 introduced into the second waveguide 905 is coupled into the first waveguide 903 as described above with respect to the pump laser 307.

[0046] In certain embodiments, the pump laser 907 is introduced into the second waveguide 905, and the probe laser 909 is introduced into the first waveguide 903 through a probe laser source. In the presence of a resonant frequency signal, the probe laser 909 can be absorbed by a point defect within the first waveguide 903 such that the power of the probe laser 909 propagating within the first waveguide 903 experiences a reduction in power as the probe laser propagates through the absorption region 901.

[0047] To monitor the power of the probe laser 909 within the first waveguide 903 after propagating through the absorption region 901, the waveguide system 900 can include a filter 915. In certain embodiments, the filter 915 can receive light from the first waveguide 903 after the light has passed through the absorption region 901. The filter 915 can reflect light at the frequency of the probe laser 909 through a reflection port 913 and allow light at other frequencies (such as fluorescence frequencies) to pass through to a filter output port 911. The pump laser 907 passes through a pump outlet port 917 after leaving the absorption region 901. In some specific implementations, the power of the pump laser 907 at the pump outlet port 917 can be substantially equal to or close to zero because most of the pump laser 907 can be coupled into the first waveguide 903.

[0048] In some embodiments, the light at the reflection port 913 can be coupled to a light detection device (such as a photodetector or a camera), where the light detection device monitors the intensity of the received light. During operation, microwave radiation or other radio frequency signals can be emitted around the absorption region, where the microwave radiation sweeps through a range of frequencies including the possible resonant frequencies of the first material. For example, the magnetometer including the waveguide system 900 can also include a radio frequency (RF) transmitter controlled by a processing device. The RF transmitter can be an antenna or other similar device that emits RF energy at a specific frequency. Additionally, the processing device can direct the RF transmitter to sweep through a range of frequencies when it emits RF energy, where the range of frequencies includes the resonant frequency of the first material.

[0049] In additional embodiments, the light detection device can monitor the light received from the reflection port 913 and provide a signal associated with the intensity of the received light. The processing device can receive the signal and correlate the intensity of the received light with the frequency of the RF energy applied to the absorption region 901 by the RF transmitter when measuring the intensity of the received light. The processing device can then execute computer-executable instructions that identify the applied frequency associated with a decrease in light intensity. The processing device can determine the identified frequency as the resonant frequency and calculate the magnitude and direction of the magnetic field applied to the absorption region 901.

[0050] The processing device can be implemented using software, firmware, hardware, or other suitable combinations thereof. The processing device and / or other computing devices can be supplemented or incorporated with a specially designed application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). The processing unit and other competing devices can also include software programs, firmware, or other computer-readable instructions or operate with them to perform various processing tasks, calculations, and control functions used in the present methods and systems.

[0051] Moreover, the methods described herein can be implemented by computer-executable instructions (such as program modules or components) executed by at least one processing unit (such as a processing device). Generally, program modules include routines, programs, objects, data components, data structures, algorithms, etc. that perform specific tasks or implement specific abstract data types. Various processing tasks, calculations, and instructions for generating other data used in the operations of the methods described herein can be implemented in software, firmware, or other computer-readable instructions. These instructions are typically stored on any suitable computer program product that includes a computer-readable medium for storing computer-readable instructions or data structures. The computer-readable medium can be any available medium that can be accessed by a general-purpose or special-purpose computer or processor or any programmable logic device. In certain specific implementations, the computer-readable medium can be stored on a memory unit in communication with the processing device.

[0052] Suitable computer-readable storage media, such as those found as part of a memory unit in communication with a processing device, can include, for example, non-volatile memory devices, including semiconductor memory devices such as random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), or flash memory devices; magnetic disks such as internal hard disks and removable disks; optical disc storage devices such as compact discs (CDs), digital versatile discs (DVDs), Blu-ray discs; or any other medium that can be used to carry or store the desired program code in the form of computer-executable instructions or data structures.

[0053] Figure 10 is a flowchart of a method 1000 for fabricating a waveguide structure for detecting a magnetic field. Method 1000 proceeds at 1001, where a waveguide layer is formed. To form the waveguide layer, method 1000 proceeds at 1003, where a first waveguide is formed of a first material. For example, the first waveguide can be formed of NV diamond, silicon carbide, and other materials having similar physical properties. Additionally, method 1000 proceeds at 1005, where a second waveguide is formed by positioning it along a coupling length adjacent to the first waveguide. For example, the second waveguide can be positioned such that light propagating within the second waveguide is coupled into the first waveguide.

[0054] In an additional embodiment, when forming the waveguide layer, method 1000 proceeds at 1007, where a probe laser source is coupled to the first waveguide. For example, the probe laser source can be coupled to the first waveguide and configured to emit a probe laser into the first waveguide. Additionally, the method proceeds at 1009, where a pump laser source is coupled to the second waveguide. For example, the pump laser source can be coupled to the second waveguide and configured to emit a pump laser into the second waveguide at a wavelength that causes the first material to absorb the probe laser when the waveguide layer is exposed to one or more resonant frequencies of the first material.

[0055] Exemplary Embodiments

[0056] Example 1 includes a device that includes: a substrate; a radio frequency transmitter that emits energy in a radio frequency range; a waveguide layer formed on the substrate, the waveguide layer including: a first waveguide of a first material, where a probe laser propagates within the first waveguide; and a second waveguide, where the second waveguide is positioned along a coupling length adjacent to the first waveguide such that a pump laser propagating within the second waveguide is coupled into the first waveguide along the coupling length, where the pump laser causes the first material to absorb the probe laser at one or more frequencies in the frequency range; and a processing device that calculates a magnetic field strength based on the identification of the one or more frequencies.

[0057] Example 2 includes the device according to Example 1, wherein the first material is nitrogen-vacancy diamond.

[0058] Example 3 includes the device according to any one of Examples 1 to 2, wherein the second material is a nitride.

[0059] Example 4 includes the device according to any one of Examples 1 to 3, wherein the processing device calculates the magnetic field direction based on the identification of the one or more frequencies.

[0060] Example 5 includes the device according to any one of Examples 1 to 4, wherein the output of the first waveguide is provided to the optical detection device.

[0061] Example 6 includes the device according to Example 5, wherein the output of the first waveguide is provided to the optical detection device through a filter, and the filter provides light at the frequency of the probing laser to the optical detection device.

[0062] Example 7 includes the device according to any one of Examples 1 to 6, wherein the pump laser is linearly absorbed by the first material of the first waveguide along the coupling length from the second waveguide.

[0063] Example 8 includes the device according to any one of Examples 1 to 7, wherein the width of the second waveguide varies along the coupling length.

[0064] Example 9 includes the device according to any one of Examples 1 to 8, wherein the distance between the first waveguide and the second waveguide varies along the coupling length.

[0065] Example 10 includes a method, the method comprising: forming a waveguide layer, wherein forming the waveguide layer includes: forming a first waveguide of a first material; and forming a second waveguide positioned close to the first waveguide along a coupling length such that light propagating in the second waveguide is coupled into the first waveguide along the coupling length; coupling a probing laser source to the first waveguide, wherein the probing laser source is configured to emit a probing laser into the first waveguide; and coupling a pump laser source to the second waveguide, wherein the pump laser source is configured to emit a pump laser into the second waveguide at a wavelength that causes the first material to absorb the probing laser when the waveguide layer is exposed to one or more resonant frequencies of the first material.

[0066] Example 11 includes the method according to Example 10, wherein the first material is nitrogen-vacancy diamond.

[0067] Example 12 includes the method according to any one of Examples 10 to 11, wherein the second material is a nitride.

[0068] Example 13 includes the method according to any one of Examples 10 to 12, and further includes calculating a magnetic field direction based on the identification of one or more resonance frequencies.

[0069] Example 14 includes the method according to any one of Examples 10 to 12, and further includes providing the output of the first waveguide to an optical detection device.

[0070] Example 15 includes the method according to Example 14, wherein providing the output of the first waveguide to an optical detection device includes passing the output of the first waveguide through a filter that reflects light at the frequency of the probing laser by a reflection port coupled to the optical detection device.

[0071] Example 16 includes the method according to any one of Examples 10 to 15, wherein the physical relationship between the first waveguide and the second waveguide along the coupling length causes the pump laser to be linearly absorbed by the first material of the first waveguide from the second waveguide along the coupling length.

[0072] Example 17 includes the method according to Example 16, wherein the physical relationship between the first waveguide and the second waveguide includes the width of the second waveguide that varies through the coupling length.

[0073] Example 18 includes the method according to any one of Examples 16 to 17, wherein the physical relationship between the first waveguide and the second waveguide includes the distance between the first waveguide and the second waveguide that varies through the coupling length.

[0074] Example 19 includes a system, the system includes: a pump laser source that provides a pump laser; a probing laser source that provides a probing laser; a radio frequency transmitter that emits energy in a frequency range; an absorption region that includes: a first waveguide of a first material, wherein the probing laser is coupled into the first waveguide; and a second waveguide, wherein the pump laser is coupled into the second waveguide, the second waveguide is positioned close to the first waveguide along a coupling length such that the propagating pump laser is coupled into the first waveguide along the coupling length, wherein the pump laser causes the first material to absorb the probing laser at one or more frequencies in the frequency range; and a filter that is coupled to the output of the first waveguide, the filter provides filtered probing laser through an output port; an optical detection device that is coupled to the output port; a processing device that calculates a magnetic field strength based on the identification of the one or more frequencies associated with the reduced intensity of the probing laser detected by the optical detection device.

[0075] Embodiment 20 includes the system according to Embodiment 19, wherein the physical relationship between the first waveguide and the second waveguide along the coupling length causes the pump laser to be linearly absorbed by the first material of the first waveguide from the second waveguide along the coupling length.

[0076] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. It is, therefore, evident that the invention is limited only by the claims and their equivalents.

Claims

1. A device for an integrated photonic quantum vector magnetometer, comprising: a substrate (311); a radio frequency transmitter that emits energy in the radio frequency range; a waveguide layer (301) formed on the substrate (311), the waveguide layer (301) comprising: a first waveguide (303) of a first material, wherein a probe laser (309) source is coupled to the first waveguide (303), the probe laser (309) source being configured to emit a probe laser (309), and the probe laser (309) propagating within the first waveguide (303); and a second waveguide (305) of a second material, wherein the second waveguide (305) is positioned along a coupling length adjacent to the first waveguide (303) such that a pump laser (307) propagating within the second waveguide (305) is coupled into the first waveguide (303) along the coupling length, wherein the pump laser (307) causes the first material to absorb the probe laser (309) at one or more frequencies in the radio frequency range; and a processing device that calculates a magnetic field strength based on an identification of the one or more frequencies.

2. The device according to claim 1, wherein the pump laser (307) is linearly absorbed by the first material of the first waveguide (303) from the second waveguide (305) along the coupling length.

3. A method for an integrated photonic quantum vector magnetometer, comprising: forming a waveguide layer (301), wherein forming the waveguide layer (301) comprises: forming a first waveguide (303) of a first material; and forming a second waveguide (305) of a second material, the second waveguide being positioned along a coupling length adjacent to the first waveguide (303) such that light propagating within the second waveguide (305) is coupled into the first waveguide (303) along the coupling length; coupling a probe laser (309) source to the first waveguide (303), wherein the probe laser (309) source is configured to emit a probe laser (309) into the first waveguide (303); and coupling a pump laser (307) source to the second waveguide (305), wherein the pump laser (307) source is configured to emit a pump laser (307) into the second waveguide (305) at a wavelength that causes the first material to absorb the probe laser (309) when the waveguide layer (301) is exposed to one or more resonant frequencies of the first material.

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