An ultrastrong field confinement laser based on coupled nanowire pairs

Abstract

This invention discloses an extremely strong field confinement laser based on a coupled nanowire pair. It comprises a pair of side-by-side nanowires forming a nanoscale slit between them; a light beam illuminating the nanowires; the nanowires emit light upon illumination, the emitted light is confined around the slit and propagates along the slit, is amplified by stimulation, and is emitted as the laser's output light. This invention achieves ultra-strong optical field confinement down to approximately 0.3 nm by assembling two nanowires into a coupled nanowire pair, thereby forming an all-dielectric cavity with a slit structure approximately 1 nm wide, providing a novel approach to realizing nanolasers with sub-nanometer field confinement.

Description

Technical Field

[0001] This invention relates to a laser in the fields of nanophotonics and laser optics research, and particularly to a novel laser with a strong optical field confinement mode and its fabrication method. Background Technology

[0002] Stronger field confinement in laser light fields is crucial for realizing light-matter interactions at smaller scales and can be applied in a range of fields, from optical microscopy and sensing to photolithography and information technology. From the early stages of laser technology development, researchers have been striving to achieve lasing modes with stronger field confinement. Due to diffraction limitations, a dielectric cavity typically cannot confine its modes to below half a wavelength. Later, plasmonic nanocavities achieved lasing fields with mode sizes confined to λ / 30, far exceeding the diffraction limit, where λ represents the wavelength of the emitted laser, and demonstrated a range of applications such as photonic interconnects and sensing. However, due to the mutual constraints between optical confinement and the intrinsic losses of surface plasmons caused by free electron oscillations within the metal, further compressing the mode size of surface plasmonic lasers is difficult to achieve due to insufficient gain. Furthermore, for a surface plasmonic nanolaser, as optical confinement increases, the momentum mismatch between the intracavity mode and the external free space rapidly intensifies, meaning that the efficiency of light-external matter interaction decreases in practical applications.

[0003] On the other hand, by applying electromagnetic boundary conditions, researchers have recently achieved strong field confinement down to the 10 nm scale in all-dielectric structures such as slit waveguides and bowtie structures. This suggests that if the structure size can be further reduced, such all-dielectric structures may be able to achieve field confinement exceeding that of plasmonic nanostructures. Moreover, compared to plasmonic confinement, all-dielectric confinement has lower optical loss and smaller photon momentum mismatch, meaning it can overcome the inherent problems of thermally induced damage and low output efficiency of plasmonic nanolaser cavities. However, due to the limitations of micro- and nanofabrication processes, achieving extremely strong field confinement below the 10 nm scale has always been a highly challenging problem. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing an extremely strong field confinement laser based on coupled nanowire pairs, thereby realizing the extremely strong field confinement laser and its fabrication method.

[0005] The technical means adopted by the present invention to solve the above-mentioned technical problems are as follows:

[0006] I. An extremely strong field confinement laser based on coupled nanowire pairs, such as Figure 1 As shown, the laser used in the specific implementation is as follows:

[0007] It includes a pair of nanowires side by side, forming a coupled nanowire pair, with a nanoscale slit between the pair of nanowires;

[0008] This includes a light beam illuminating the nanowires, which emit light after being irradiated by the light beam. The emitted light is confined around the slit and propagates along the slit, is amplified by stimulation, and is emitted as the output light of the laser.

[0009] The light beam is a pulsed light.

[0010] The pair of side-by-side nanowires consists of two nanowires arranged side-by-side along the same straight line or curve, with equal spacing between the slits between the two nanowires.

[0011] The width of the slit in the horizontal direction is approximately 1 nm.

[0012] The nanowires have a diameter of 50-500 nm and a surface roughness of about 1 nm.

[0013] The nanoscale slit formed between a pair of nanowires is naturally created by the nanoscale roughness of the nanowire surface, and its size is determined by the surface roughness.

[0014] The field confinement formed in the slit includes a field confinement of approximately 0.3 nm in the horizontal direction (x direction) along the parallel direction between the nanowires and a field confinement of approximately 1 nm in the vertical direction (y direction) perpendicular to the parallel direction of the nanowires.

[0015] The extremely strong field confinement described in this invention refers to a confinement scale of 1 nm in the xy direction, as mentioned above. Existing solutions typically only achieve field confinement on the order of 10 nm; the field intensity at the point of strongest light in the slit is approximately 30 dB higher than the surrounding background field.

[0016] The materials of the nanowires include group III-V or group II-VI semiconductor nanowires, or active nanowires such as perovskite nanowires.

[0017] The cross-sectional shape of the nanowires is polygonal, but not limited to this.

[0018] The cross-sectional shapes of the pair of nanowires can be the same or different.

[0019] II. A method for fabricating a laser, characterized by:

[0020] A nanowire is cut into two parts using a micro / nano probe to form two nanowires. The two nanowires are then moved to sit side by side, naturally forming a pair of parallel nanowires. A light source is placed above the pair of coupled nanowires to irradiate the pair with an excitation beam, thereby creating an extremely strong field confinement laser.

[0021] The method then uses focused ion beam cutting to cut the two ends of the nanowire flush, forming a Fabry-Perot resonant cavity.

[0022] This invention fabricates lasers through the aforementioned micro-nano manipulation method, achieving effects and results that traditional high-tech processes cannot, in a simple and effective way, and solving the precision problem that existing photolithography, etching and other processes cannot reach.

[0023] The structure of this invention cannot be fabricated using conventional methods such as photolithography and etching. Photolithography can only achieve slits with a width of up to 10 nm between nanowires, not slits with a width of 1 nm.

[0024] Two high-gain nanowires were assembled into a coupled nanowire pair using micro-nano manipulation techniques. The ends were then cut flush to form a Fabry-Perot resonator. Due to the diameter and nanoscale roughness of the nanowires, a slit of approximately 1 nm naturally formed between them. This cross-section allows for the formation of waveguide modes (TE-like). 01 The model exhibits field confinement of approximately 0.3 nm in the horizontal direction and approximately 1 nm in the vertical direction. Under excitation by excitation light, the nanowire can generate laser light with sub-nanometer optical field confinement.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] This invention assembles two nanowires into a coupled nanowire pair to form an all-dielectric cavity with a slit structure approximately 1 nm wide. This invention achieves an ultra-strong field-confined nanowire laser with a field width as low as approximately 0.3 nm. The structure provides a novel approach to realizing sub-nanometer field-confined nanolasers, propelling laser-related science and technology towards the sub-nanometer scale.

[0027] This invention utilizes a pair of photonic lasers based on coupled nanowire pairs to bypass the constraints and losses in surface plasmon structures, and provides sub-nanometer-scale field constraints that are almost impossible to achieve with existing methods. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the present invention; 1-coupled cadmium selenide nanowire pair, 2-1nm slit, 3-excitation light irradiation.

[0029] Figure 2 These are high-resolution transmission electron microscope images of the cross-section of the cadmium selenide nanowire pair in this invention example, as well as magnified images of the slit.

[0030] Figure 3 This is a simulation diagram of the optical field of the cadmium selenide nanowire pair in an example of the present invention.

[0031] Figure 4This is a microscope image of the laser emitted from the end face of the nanowire laser in this invention example.

[0032] Figure 5 These are spectra at different excitation intensities in an example of the present invention. In the figure: nanowire 1, slit 2, beam 3.

[0033] Figure 6 The figure shows the experimental results of the coupled nanowire pairs in the embodiment under different excitation power densities.

[0034] Figure 7 This is an example scenario diagram of the coupled nanowire pair in the embodiment. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] like Figure 1 and Figure 7 As shown, the laser used in the specific implementation is as follows:

[0037] It includes a pair of side-by-side nanowires 1, forming a coupled nanowire pair, with a nanoscale slit 2 formed between the pair of nanowires 1;

[0038] The light beam 3 is irradiated onto the nanowire 1. After being irradiated by the light beam, the nanowire 1 emits light. The emitted light is confined in the slit and transmitted along the slit 2, amplified by stimulation, and emitted as the output light of the laser.

[0039] Beam 3 is a pulsed light, and its wavelength is shorter than the operating wavelength of the laser output light.

[0040] A pair of side-by-side nanowires 1 consists of two nanowires arranged side-by-side along the same straight line or curve, with equal spacing between the slits between the two nanowires.

[0041] In practice, cadmium selenide nanowires are placed on a low-refractive-index magnesium fluoride substrate. Excited by a 532nm nanosecond excitation source, laser emission is generated due to the Fabry-Perot resonant cavity formed at the end face. Figure 7 As shown. The fabrication process of the coupled nanowire pairs is as follows. Figure 2 As shown:

[0042] First, a fiber optic probe is used to push the middle of the nanowire, causing it to bend until it breaks, thus splitting the nanowire into two segments.

[0043] Next, the two nanowires were pushed to the edge of the substrate by micro-nano manipulation using fiber optic probes, forming a coupled nanowire pair structure with each other in side-by-side contact.

[0044] Finally, the nanowires were cut at both ends using a focused ion beam to make them flush. The cross-section of the prepared nanowires is shown below. Figure 3 As shown.

[0045] In the specific implementation, the width of the slit 2 in the horizontal direction is 1 nm, the diameter of the nanowire 1 is 166 nm, the surface roughness is 1 nm, the nanowire material is cadmium selenide, and the cross-sectional shape of the nanowire is hexagonal.

[0046] High-resolution transmission electron microscopy revealed a slit of approximately 1 nm in the cross-section. Based on this structure, the light field distribution was simulated using Comsol simulation software, such as... Figure 4 As shown, at the slit, the light field intensity is constrained by a field strength of approximately 0.3 nm in the horizontal direction and approximately 1 nm in the vertical direction. The field strength at the point where the light field is strongest in the slit is about 30 dB higher than the surrounding background field.

[0047] When excited by excitation light, the excitation intensity exceeds the nanowire laser threshold (0.8 MW / cm²). 2 ),Depend on Figure 5 As can be seen, the output at the end face becomes brighter, and interference rings can be observed due to the increased laser coherence.

[0048] Figure 6 Experimental results for this coupled nanowire pair at different excitation power densities are presented. With increasing excitation power density, two laser peaks appear near 712 nm and 715 nm. At 1 MW / cm²... 2 At the excitation power density, the output intensity at the ends of the two peaks changes with the angle as follows: Figure 6 As shown in the sub-diagram, the TE class obtained from the simulation... 01 The output intensity of the mode matches the angle well, indicating that both peaks correspond to the TE type. 01 The model was then established. From this, it was concluded that a nanolaser with sub-nanometer extreme optical field confinement was experimentally realized.

Claims

1. An ultrastrong field confinement laser based on a coupled nanowire pair, characterized in that: it comprises a pair of parallel nanowires (1), a nanoscale gap (2) is formed between the pair of nanowires (1); it comprises a light beam (3) irradiated to the nanowires, the nanowires (1) emit light after being irradiated by the light beam, the light emission is confined in the gap (2) and transmitted along the gap, amplified by stimulated emission and emitted as output light of the laser; the pair of parallel nanowires (1) is composed of two nanowires arranged in parallel along the same straight line or curve, and the gap between the two nanowires has equal spacing at each position; the gap (2) has a width of about 1 nm in the horizontal direction; the gap (2) forms a sub-nanometer field confinement, including a field confinement of 0.3 nm in size in the horizontal direction along the parallel direction between the nanowires and a field confinement of 1 nm in size in the vertical direction perpendicular to the parallel direction of the nanowires. The light beam (3) is a pulsed light. The nanowires (1) have a diameter of 50-500 nm and a surface roughness of about 1 nm. The nanowires (1) have a diameter of 50-500 nm and a surface roughness of about 1 nm. The nanowires (1) have a diameter of 50-500 nm and a surface roughness of about 1 nm. The nanowires (1) have a diameter of 50-500 nm and a surface roughness of about 1 nm.

2. The ultrastrong field confinement laser based on coupled nanowire pairs according to claim 1, characterized in that: The nanowires (1) have a diameter of 50-500 nm and a surface roughness of about 1 nm.

3. The ultrastrong field confinement laser based on coupled nanowire pairs according to claim 1, characterized in that:

7. A preparation method for the laser of any one of claims 1-6, characterized in that: a nanowire is cut into two parts by a micro-nano probe to form two nanowires, the two nanowires are arranged in parallel by being nudged to be in close proximity to each other, and a pair of parallel nanowires is naturally formed; a light source is arranged above the coupled nanowire pair, and the light source irradiates an excitation light beam to the coupled nanowire pair, thereby preparing an ultrastrong field confinement laser.

4. The ultrastrong field confinement laser based on coupled nanowire pairs of claim 1, wherein:

8. The preparation method of the laser of claim 7, characterized in that: the method further utilizes focused ion beam cutting to cut the two ends of the nanowire to be flush, thereby forming a Fabry-Perot resonant cavity.

5. The ultrastrong field confinement laser based on coupled nanowire pairs according to claim 1, characterized in that: ​ 6. The ultrastrong field confinement laser based on coupled nanowire pairs according to claim 1, characterized in that: ​ ​ ​ ​ ​

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