Pcsel for monitoring glucose

Abstract

To describe a glucose monitor having one or more photonic crystal surface light-emitting lasers (PCSEL).SOLUTION: The PCSEL includes a plurality of photonic crystal parts. Each photonic crystal part can operate to emit light with different wavelengths. The horizontal light emission of each photonic crystal part can be limited by an edge lattice part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 519,805, entitled "PCSEL FOR GLUCOSE MONITORING," filed August 15, 2023, the entire contents of which are incorporated herein by reference. [Background technology]

[0002]

[0002] The limitations and drawbacks of conventional systems and methods for glucose monitoring will become apparent to those skilled in the art by 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 systems and methods disclosed in this specification use a photonic crystal surface-emitting laser (PCSEL) to monitor glucose substantially as shown in and / or described in connection with at least one of the figures, and as more fully described in the claims. [Brief description of the drawings]

[0004] [Figure 1] FIG. 4 illustrates a first example top emitter structure having a PCSEL in accordance with various implementations of the present disclosure. [Diagram 2]

[0005] 1A-1C are diagrams illustrating example bottom emitter structures having PCSELs in accordance with various implementations of the present disclosure. [Diagram 3]

[0006] FIG. 2 illustrates a second example top-emitter structure having a PCSEL in accordance with various implementations of the present disclosure. [Figure 4]

[0007] FIG. 13 illustrates a third example top-emitter structure having a PCSEL in accordance with various implementations of the present disclosure. [Diagram 5]

[0008] 1A-1C show example structures for co-integrating two monolithic arrays with different wavelength ranges on the same substrate, in accordance with various implementations of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005]

[0009] Millions of people suffer from diabetes and require glucose monitoring multiple times per day. However, currently available monitoring systems are invasive. Although monitoring systems today can use lasers, these systems are not sufficient. For example, known existing solutions with 2.0-2.4 μm laser sources include bulk lasers (such as excimer lasers) that are not applicable for small, wearable glucose sensor applications. Another existing solution includes distributed feedback laser (DFB) lasers. For glucose monitoring applications with DFB lasers, the epi-stacks for each wavelength are different, and the DFB lasers must be integrated on the same platform. This integration limits the number of wavelengths that can be used with high yield, which also makes such solutions expensive. Furthermore, existing solutions suffer from a relatively wide spectral bandwidth (SBW) per wavelength (e.g., around 1 nm) and poor beam quality (e.g., M 2 >1.1). Tunable lasers are also suitable for emitting in the 2.0-2.4 μm range, but precise wavelength tuning of the laser is very difficult.

[0006]

[0010] The present disclosure describes non-invasive systems and methods for glucose monitoring. As described below, in accordance with various implementations of the present disclosure, 2.0-2.4 μm photonic crystal surface-emitting lasers (PCSELs) can be used for non-invasive glucose monitoring and other medical optical sensing applications. PCSELs provide excellent beam purity and excellent beam quality for such optical sensing applications. Furthermore, PCSELs enable monolithic integration for the range of wavelengths that may be required for absorption-based glucose sensing applications.

[0007]

[0011] The emission wavelength of PCSELs is defined through photonic crystal lattice design and can be limited by etching tool capabilities. Wavelength precision is significantly better than existing solutions. PCSELs offer significantly lower SBW (e.g., <0.1 nm) and superior beam quality (e.g., M 2 <1.1). PCSELs allow monolithic integration for multiple wavelengths. Thus, a single epi design can be used for multiple wavelengths.

[0008]

[0012] Although this disclosure describes the use of monolithic PCSEL arrays for glucose monitoring at wavelengths from 2.0 to 2.4 μm, other wavelength ranges may be supported by using a different set of materials for the active region. For example, for wavelengths from 2.0 to 2.4 μm, highly strained InGaAs and GaSb materials may be used for the active region, since the gain of InGaAs and GaSb supports this wavelength range.

[0009]

[0013] The PCSEL emission direction can be either top (FIGS. 1, 3, 4, and 5) or bottom (FIG. 2) depending on the application requirements.

[0014] FIG. 1 illustrates a first example top-emitter structure having a PCSEL in accordance with various implementations of the present disclosure.

[0010]

[0015] Photonic crystal (PC) gratings L1, L2...Ln are designed to output wavelengths λ1, λ2...λn, respectively. For large optical apertures (e.g., OA>30 μm), horizontal modes can be constrained by the gratings. The epistacks (above and / or below the PC) can contain p-n junctions.

[0011]

[0016] FIG. 2 illustrates an example bottom-emitter structure having a PCSEL according to various implementations of the present disclosure.

[0017] Similar to Figure 1, the PC gratings L1, L2...Ln are designed to output wavelengths λ1, λ2...λn, respectively. For large optical apertures (e.g., OA>30μm), horizontal modes may be constrained by the gratings. The epi-stack above the PC may have a top distributed Bragg reflector (DBR) that is 100% reflective. Below the PC the epi-stack may have a bottom DBR that is not fully reflective.

[0012]

[0018] FIG. 3 illustrates a second example top-emitter structure having a PCSEL according to various implementations of the present disclosure.

[0019] Similar to Figures 1 and 2, PC gratings L1, L2...Ln are designed to output wavelengths λ1, λ2...λn, respectively. The horizontal modes in Figure 3 are constrained by edge gratings (Le). Edge gratings allow OA<30μm. Edge gratings can also be used for the small aperture of the bottom-emitting configuration in Figure 2.

[0013]

[0020] FIG. 4 illustrates a third example top-emitter structure having a PCSEL in accordance with various implementations of the present disclosure.

[0021] Similar to Figures 1-3, PC gratings L1, L2...Ln are designed to output wavelengths λ1, λ2...λn, respectively. Optical elements (OE1, OE2,..., OEn) are added to Figure 4. The optical elements may comprise lenses and / or diffusers that may be placed (e.g., etched, deposited) on the emitting surface for beam shaping purposes.

[0014]

[0022] The lateral modes in a PCSEL are constrained by the photonic crystal for large optical apertures (>30 μm) or by a secondary (outer) photonic crystal for small optical apertures (<30 μm). The "outer" photonic crystal has a smaller photonic band gap and therefore acts as a reflector.

[0015]

[0023] In the case of GaSb in the active region, the epitack for the p-n junction implementation consists of a GaAs substrate and cladding layers. The photonic crystal layers can include GaAs or GaSb.

[0016]

[0024] The vertical mirror stack can comprise GaAs and AlGaAs mirrors covering the required wavelength range. Due to lattice mismatch, additional lattice matching layers or wafer bonding may be required for the GaSb active region.

[0017]

[0025] For a solution with strained InGaAs in the active region, regrowth can be used to form the photonic crystal and the epilayers on top of the crystal. The epistack for InGaAs in the active region can include an InP substrate and cladding layers, a reflector, and a GaInAsP photonic crystal.

[0018]

[0026] For both GaSb and InGaAs solutions, at least two stack configurations are possible: one possible configuration includes p on one side of the active region and n on the other; another configuration includes n on both sides of the active region with a tunnel junction (TJ) between them.

[0019]

[0027] PCSEL arrays can be monolithically fabricated for a range of wavelengths. The wavelength range within each monolithic array can depend on the uniformity requirements. The power uniformity across wavelengths depends on the gain peak of the active region material. The wavelength range may or may not cover the 2.0-2.4 μm range. If the wavelength range does not cover the 2.0-2.4 μm range, multiple monolithic arrays can be used for the full range.

[0020]

[0028] The wavelength of each device in the array is different and can be controlled by lithography (photonic crystal design), in which case the lattice constant is different for each device.

[0029] The vertical mirror stack can be shared among all wavelengths or a subset of wavelengths depending on the uniformity requirements. The total response is a combination of the gain curve response and the mirror design, and this feature can be used to design a "flat" response and therefore better uniformity.

[0021]

[0030] FIG. 5 illustrates an example structure for co-integrating two monolithic arrays with different wavelength ranges on the same substrate, according to various implementations of the present disclosure.

[0031] Multiple monolithic arrays could be integrated on the same platform, for example using a pick and place process. Each monolithic array could have an individually optimized DBR stack. Due to the low spectral bandwidth and high central wavelength design precision of PCSELs, the achievable wavelength spacing could be <5nm.

[0022]

[0032] The wavelengths may be spaced with respect to temperature. The center wavelength of each device may have the same thermal shift. The refractive index may vary with temperature. For example, the reflectivity may vary by 0.07 nm per degree Celsius. The relative wavelength spacing may be maintained with respect to temperature. Thus, a glucose monitoring application with a PCSEL may not require cooling. The wavelength spacing may depend on the etching capability.

[0023]

[0033] The monitoring system can be fitted with integrated optics (i.e., stacking lenses and / or diffusers). The lasers in the array can be powered on simultaneously or sequentially. To support sequential wavelength sweeping, each laser can have a separate metal contact and driver.

[0024]

[0034] As used herein, the terms "circuit" and "circuitry" refer to physical electronic components (i.e., hardware) and any software and / or firmware ("code") that may comprise, be executed by, and / or otherwise be associated with hardware. As used herein, a particular processor and memory may comprise a first "circuit" when executing a first one or more lines of code, and a second "circuit" when executing a second one or more lines of code. As used herein, "and / or" means any one or more of the items in a list joined by "and / or". As an example, "x and / or y" means any element of the three-element set {(x),(y),(x,y)}. As another example, "x, y, and / or z" means any element of the seven-element set {(x),(y),(z),(x,y),(x,z),(y,z),(x,y,z)}. As used herein, the term "exemplary" means serving as a non-limiting example, instance, or illustration. As used herein, the terms "eg" and "for example" invoke a list of one or more non-limiting examples, instances, or illustrations. As used herein, circuitry is "operable" to perform a function whenever the circuitry comprises the necessary hardware and code (if any) and whether or not performance of that function is disabled or enabled (e.g., by a user-configurable setting, factory trim, etc.). As used herein, the term "based on" means "based at least in part on." For example, "x based on y" means that "x" is based at least in part on "y" (e.g., could also be based on z).

[0025]

[0035] Although the method and / or system have been described with reference to several implementations, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the method and / or system. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope of the disclosure. Thus, the method and / or system is not limited to the particular implementations disclosed, but rather, the method and / or system is intended to include all implementations falling within the scope of the appended claims.

Claims

1. a first photonic crystal portion operable to out-couple light of a first wavelength in a vertical direction; a second photonic crystal portion operable to decouple light in the vertical direction at a second wavelength different from the first wavelength; A laser device comprising:

2. 2. The laser device of claim 1, wherein the first photonic crystal portion and the second photonic crystal portion are disposed in the same fabrication layer.

3. 2. The laser device according to claim 1, a first epitaxy layer operatively coupled beneath the first photonic crystal portion and the second photonic crystal portion; a second epitaxy layer operatively coupled beneath the first photonic crystal portion and the second photonic crystal portion; A laser device comprising:

4. 10. The laser device of claim 1, wherein a glucose monitor comprises the laser device.

5. 10. The laser device of claim 1, wherein the laser device is a bottom emitting laser.

6. 10. The laser device of claim 1, wherein the laser device is a top emitting laser.

7. 2. The laser device according to claim 1, wherein the first wavelength and the second wavelength are 2.0 to 2.4 μm.

8. 2. The laser device according to claim 1, one or more edge grating sections adjacent the first photonic crystal section are operable to confine a horizontal mode of the first wavelength; one or more edge grating sections adjacent the second photonic crystal section are operable to confine horizontal modes of the second wavelength. Laser device.

9. 2. The laser device according to claim 1, One or more optical elements disposed on the light emitting surface A laser device comprising:

10. 10. The laser device of claim 1, wherein the first wavelength and the second wavelength are determined according to a temperature.

11. 1. A method of fabricating a laser device, comprising the steps of: Fabricating a first photonic crystal portion operable to decouple vertically oriented light of a first wavelength; fabricating a second photonic crystal portion operable to decouple light in the vertical direction at a second wavelength different from the first wavelength; The method includes:

12. The method of claim 11 , wherein the first photonic crystal portion and the second photonic crystal portion are disposed in a same fabrication layer.

13. 12. The method of claim 11, operatively fabricating a first epitaxy layer prior to fabricating the first photonic crystal portion and the second photonic crystal portion; fabricating a second epitaxy layer on the first photonic crystal portion and the second photonic crystal portion; The method includes:

14. The method of claim 11 , wherein a glucose monitor includes the laser device.

15. The method of claim 11 , wherein the laser device is a bottom emitting laser.

16. 12. The method of claim 11, wherein the laser device is a top emitting laser.

17. The method of claim 11, wherein the first wavelength and the second wavelength are between 2.0 and 2.4 μm.

18. 12. The method of claim 11, fabricating one or more edge grating sections adjacent to the first photonic crystal section and operable to constrain horizontal modes of the first wavelength; fabricating one or more edge grating sections adjacent to the second photonic crystal section and operable to constrain horizontal modes of the second wavelength; The method includes:

19. 12. The method of claim 11, Positioning one or more optical elements on the light emitting surface The method includes:

20. The method of claim 11 , wherein the first wavelength and the second wavelength are determined according to a temperature.

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