A wavelength-controllable hybrid plasmonic micro-nanolasers based on tpp and spp

Abstract

The application discloses a wavelength-controllable hybrid plasmonic micro-nano laser based on TPP and SPP, and belongs to the technical field of lasers, comprising a one-dimensional photonic crystal heterostructure based on coupling of a surface plasmon and a Tamm plasmon mode; the one-dimensional photonic crystal heterostructure is stacked by multiple thin films, and from top to bottom, the one-dimensional photonic crystal heterostructure comprises a metal layer, a dielectric spacer layer, a distributed Bragg reflector (DBR) and a substrate. The application adopts hybridization of two different optical modes, and enhances the interaction between surface light and matter. Compared with the TPP mode and the SPP mode, the hybrid mode solves the problem of large metal loss, and improves the Q value. In the application of the laser, the high Q value characteristic and the Purcell effect of the hybrid mode are utilized, and a four-level gain system is introduced to effectively compensate for the loss, so that the laser threshold is significantly reduced, and the problem of high threshold of the plasmonic laser is solved.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and more specifically to a wavelength-tunable hybrid plasmon laser based on TPP and SPP. Background Technology

[0002] With the current pursuit of integration and low energy consumption in the information industry, on-chip photonic integrated circuits have become an important direction for the next generation of information technology transformation, and on-chip integrated light sources are an indispensable part of this. Photonic integrated circuits often use macroscopic semiconductor laser coupling to obtain on-chip lasers, but their size and integration difficulty are high. In recent years, on-chip micro-nano lasers have become the most promising technical path for photonic integrated light sources.

[0003] Based on the optical feedback mechanism of optical resonators, micro / nano lasers include Fabry-Perot microcavity lasers, whispering-gallery mode lasers, distributed feedback lasers, and plasmonic lasers. Plasmonic lasers further include micro / nano lasers based on Tamm plasmon polaritons (TPPs) and micro / nano lasers based on surface plasmon polaritons (SPPs). Surface plasmon polariton-based micro / nano lasers utilize surface plasmon polaritons to localize light energy near the metal-dielectric interface. Their optical field scale can be much smaller than the wavelength of light, achieving deep subwavelength laser emission. Their advantages lie in their extremely strong optical field localization capability, ultra-small mode volume, and extremely high Purcell factor, making them more suitable for sensing. Tamm plasmon polariton-based micro / nano lasers successfully solve the core problem of high metal loss in traditional plasmonic lasers, localizing light within the structure and achieving high Q-value, low-loss laser emission.

[0004] Laser applications seek both low pump thresholds to conserve energy and higher stability, high modulation bandwidth, and high data transmission speeds. However, most current nanolasers still fall short of meeting the requirements of practical applications. Specifically:

[0005] (1) Existing micro-nano lasers based on F_P resonance, such as Tamm plasmonic lasers, have field distributions confined within the cavity, making it difficult to control the laser mode externally. For micro-nano lasers intended for on-chip integration, the cavity control is difficult and the stability is low.

[0006] (2) Existing nanocavity mode lasers, such as SPP lasers and TPP lasers, are limited by the intrinsic absorption of metals, resulting in large losses and relatively low Q values, which restricts their application prospects in photonic integrated systems.

[0007] Based on this, the present invention designs a wavelength-tunable hybrid plasmonic micro / nano laser based on TPP and SPP to solve the above problems. Summary of the Invention

[0008] To address the aforementioned shortcomings of existing technologies, this invention provides a wavelength-tunable hybrid plasmonic micro / nano laser based on TPP and SPP.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A wavelength-tunable hybrid plasmonic micro / nano laser based on TPP and SPP includes a one-dimensional photonic crystal heterostructure based on the coupling of surface plasmon polaritons and Tamm plasmon polariton modes. The one-dimensional photonic crystal heterostructure is formed by stacking multiple thin films, from top to bottom: a metal layer, a dielectric spacer layer, a distributed Bragg reflector (DBR), and a substrate. The DBR is formed by alternating stacking of high-refractive-index layers and low-refractive-index layers.

[0011] The metal layer (1) has a thickness of 30~35nm; the dielectric spacer layer (2) has a thickness of 270~280nm; the distributed Bragg reflector (DBR) (3) has 11 periods, the high refractive index layer has a thickness of 60~68nm, and the low refractive index layer has a thickness of 110~120nm.

[0012] Furthermore, a SiO2 covering layer is also provided on the metal layer.

[0013] Furthermore, the metal layer is an Ag film.

[0014] Furthermore, the dielectric spacer layer is a PMMA layer.

[0015] Furthermore, a four-level gain system was placed in the PMMA layer, and the laser emitted laser light at the resonance peak of 520~540nm.

[0016] Furthermore, the distributed Bragg reflector (DBR) is fabricated using magnetron sputtering or electron beam evaporation deposition.

[0017] Furthermore, the high refractive index layer is made of TiO2, and the low refractive index layer is made of MgF2.

[0018] Furthermore, the selected silver film thickness is 32nm; the selected PMMA layer thickness is 277nm; the number of periods of the distributed Bragg reflector (DBR) is selected as 11, that is, the distributed Bragg reflector (DBR) is formed by 11 pairs of TiO2 / MgF2 alternately stacked and deposited, wherein the thicknesses of TiO2 and MgF2 are 65nm and 118nm, respectively.

[0019] Compared with existing technologies, the advantages of this invention are as follows: 1. This invention employs a hybrid of two different optical modes (TPP and SPP modes) to enhance the interaction between surface light and matter. This hybrid mode (SPP-TPP hybrid mode) solves the problem of high metal loss compared to the TPP and SPP modes and improves the Q value. Without changing the thickness of metal layer 1, the Q value is increased by more than 100 times compared to the SPP mode; without changing the DBR thickness, the Q value is increased by two times compared to the TPP mode.

[0020] 2. This invention utilizes Rabi splitting to realize a hybrid micro / nano laser that combines the advantages of both TPP and SPP optical modes, enhancing the interaction between surface light and matter while maintaining stable modulation characteristics. The resonant peak shift is modulated by adding a SiO2 thin film to the surface of metal layer 1; the relatively low silicon dioxide thickness allows for a relatively large blue shift of the resonant peak.

[0021] 3. In laser applications, the high Q-value characteristics of hybrid modes and the Purcell effect are utilized, and a four-level gain system is introduced to effectively compensate for losses, significantly reducing the laser threshold and solving the problem of excessively high threshold in plasmonic lasers. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0023] Figure 1 This is a structural diagram of a wavelength-tunable hybrid plasmonic micro / nano laser based on TPP and SPP according to the present invention.

[0024] Figure 2 This is an energy-wave vector (Ek) relationship diagram for the TPP-SPP hybrid mode. The vertical axis represents wavelength, and the horizontal axis represents angle (Theta).

[0025] Figure 3 The reflectance curve was generated to select the anti-crossing point (530 nm). The vertical axis is reflectance (R), and the horizontal axis is wavelength (lambda).

[0026] Figure 4 This is a wavelength-space electric field distribution diagram for the TPP-SPP hybrid mode. The vertical axis represents wavelength (lambda), and the horizontal axis represents spatial distance (z).

[0027] Figure 5 This is a graph showing the reflectivity-wavelength relationship of SiO2 capping layers of different thicknesses. The vertical axis represents reflectivity (R), and the horizontal axis represents wavelength (Wavelength).

[0028] Figure 6 This is a graph showing the intensity-wavelength relationship for the TPP-SPP hybrid mode. The vertical axis represents intensity, and the horizontal axis represents wavelength (lambda).

[0029] Figure 7 The graph shows the relationship between the square of the optical field intensity (|E|²) and the pump power in the TPP-SPP hybrid mode. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] Example 1: Please refer to the accompanying drawings in the instruction manual. Figure 1 A wavelength-tunable hybrid plasmonic micro / nano laser based on TPP and SPP includes a one-dimensional photonic crystal heterostructure based on the coupling of surface plasmons and Tamm plasmonic polariton modes.

[0032] The one-dimensional photonic crystal heterostructure is formed by stacking multiple thin films, which, from top to bottom, are: metal layer 1, dielectric spacer layer 2, distributed Bragg mirror (DBR) 3 and substrate 4.

[0033] Furthermore, the metal layer 1 is an Ag film;

[0034] Furthermore, the distributed Bragg reflector (DBR) 3 is formed by alternating stacking of TiO2 / MgF2, and its preparation method can be magnetron sputtering, electron beam evaporation, or other deposition methods.

[0035] In this structure, metal layer 1 provides free electrons and serves as the carrier for surface plasmon polarization (SPP) modes. Dielectric spacer layer 2 controls the distance between metal layer 1 and the distributed Bragg mirror (DBR) 3, adjusting the coupling strength between the two modes (SPP and TPP). The DBR 3, composed of alternating high / low refractive index dielectrics, possesses photonic bandgap characteristics, allowing the light field to be localized within the structure and supporting transport-type plasmon polarization (TPP) modes. Substrate 4 supports the entire structure.

[0036] Incident light is obliquely incident from substrate 4. With the help of an oil mirror and transverse magnetic (TM) polarized light incident at a specific angle, the wave vector matching condition is satisfied, which excites the SPP mode at the interface between metal layer 1 and the external environment, thereby realizing the hybridization of SPP mode and TPP mode.

[0037] Furthermore, a SiO2 capping layer is also provided on the metal layer 1. By changing the thickness of the SiO2 capping layer, the wavelength shift of the TPP-SPP hybrid mode resonance peak can be controlled, thereby realizing the sensing function.

[0038] Furthermore, the dielectric spacer layer 2 is a PMMA layer.

[0039] During simulation, a four-level gain system was added to the PMMA layer (in the experiment, laser dyes or other luminescent materials can be doped into the PMMA). The laser emitted laser light at the resonance peak of 520~540nm (e.g., 530nm), successfully achieving high Q value, low threshold and tunable laser emission at a specific wavelength.

[0040] Changing the thickness of the high-refractive-index and low-refractive-index layers in the distributed Bragg reflector (DBR) 3 shifts the resonant wavelength of the TPP mode, thus affecting the resonant wavelength of the SPP-TPP hybrid mode. Furthermore, research has found that the attenuation of the TPP-SPP hybrid mode is solely due to the presence of metal layer 1; therefore, the thickness of the silver film needs to be optimized to maximize the Q (quality factor) value at 520–540 nm (e.g., 530 nm). However, since changing the silver film thickness also shifts the resonant wavelength, the thickness of the PMMA layer needs to be controlled to correct the parameters and bring the resonant wavelength back to the desired 520–540 nm (e.g., 530 nm). Too many periods in the distributed Bragg reflector (DBR) 3 reduce the excitation light coupling depth, while too few periods decrease the emitted light Q value; therefore, the number of periods in the distributed Bragg reflector (DBR) 3 also needs to be chosen appropriately.

[0041] Finally, the metal layer (1) has a thickness of 30~35nm; the dielectric spacer layer (2) has a thickness of 270~280nm; the distributed Bragg reflector (DBR) (3) has 11 periods, the high refractive index layer has a thickness of 60~68nm, and the low refractive index layer has a thickness of 110~120nm.

[0042] Further optimal parameters were determined: the selected silver film thickness was 32 nm; the selected PMMA layer thickness was 277 nm; the number of periods of the distributed Bragg reflector (DBR) 3 was selected as 11, that is, the distributed Bragg reflector (DBR) 3 is formed by 11 pairs of high refractive index layer (TiO2) / low refractive index layer (MgF2) stacked alternately, wherein the thicknesses of the high refractive index layer (TiO2) and the low refractive index layer (MgF2) are 65 nm and 118 nm, respectively.

[0043] By optimizing the above five parameters, the Q value can be increased from 62 to 126.

[0044] like Figure 2 As shown, by optimizing five structural parameters—silver film thickness, PMMA layer thickness, TiO2 layer thickness in DBR, MgF2 layer thickness, and DBR cycle number—a very obvious anti-crossover characteristic appears in the figure. This is because strong coupling occurs between TPP and SPP modes in the structure to form an SPP-TPP hybrid mode. This hybrid mode is beneficial to enhancing the interaction between light and matter.

[0045] like Figure 3 As shown, in Figure 2 By selecting the anti-crossing point (530 nm) to generate a reflectivity curve, a significant increase in Q value and coupling depth can be observed.

[0046] like Figure 4 As shown, the electric field at the resonance peak is not only distributed inside the structure, but also on the metal surface. This situation is more conducive to the modulation of the resonance wavelength.

[0047] like Figure 5 As shown, when a SiO2 capping layer is added to the silver film, the change in the SiO2 thickness will affect the SPP mode, thereby shifting the resonance peak and achieving the purpose of tunable wavelength, making the application range wider.

[0048] like Figure 6 As shown, due to the strong coupling between the TPP and SPP modes in the structure, forming an SPP-TPP hybrid mode, a four-level gain system (such as laser dye molecules) is introduced into the PMMA dielectric layer to help compensate for the loss of this hybrid mode. When the gain reaches or exceeds the loss, stimulated emission can be achieved at the resonance peak of approximately 530 nm.

[0049] like Figure 7 As shown, the threshold of laser emission decreases due to the high Q value of this hybrid mode, thus forming a dual-mode hybrid laser with high Q value and low threshold.

[0050] This invention employs a hybrid of two different optical modes (TPP and SPP modes) to enhance the interaction between surface light and matter. This hybrid mode (SPP-TPP hybrid mode) solves the problem of high metal loss compared to the TPP and SPP modes and improves the Q value. Without changing the thickness of metal layer 1, the Q value is increased by more than a hundred times compared to the SPP mode; without changing the DBR thickness, the Q value is increased by two times compared to the TPP mode.

[0051] This invention utilizes Rabi splitting to realize a hybrid micro / nano laser that combines the advantages of both TPP and SPP optical modes, enhancing the interaction between surface light and matter while maintaining stable controllability. The resonant peak shift is modulated by adding a SiO2 thin film to the surface of metal layer 1; the relatively low silicon dioxide thickness allows for a relatively large blue shift of the resonant peak.

[0052] In laser applications, the high Q-value characteristics of hybrid modes and the Purcell effect are utilized, and a four-level gain system is introduced to effectively compensate for losses, significantly reducing the laser threshold and solving the problem of excessively high threshold in plasmonic lasers.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wavelength-tunable hybrid plasmon laser based on TPP and SPP, characterized in that: The invention includes a one-dimensional photonic crystal heterostructure based on the coupling of surface plasmon polaritons and Tamm plasmon polariton modes; the one-dimensional photonic crystal heterostructure is formed by stacking multiple thin films, which are arranged from top to bottom as follows: a metal layer (1), a dielectric spacer layer (2), a distributed Bragg mirror (DBR) (3), and a substrate (4). The metal layer (1) is an Ag film with a thickness of 30~35nm; a SiO2 capping layer is also provided on the metal layer (1). By changing the thickness of the SiO2 capping layer, the wavelength shift of the TPP-SPP hybrid mode resonance peak is controlled. The dielectric spacer layer (2) is a PMMA layer with a thickness of 270~280nm; a four-level gain system is placed in the PMMA layer, and the laser emits laser light at the resonance peak of 520~540nm; The distributed Bragg reflector DBR (3) is formed by alternating stacking of high refractive index layer and low refractive index layer; the high refractive index layer is TiO2 and the low refractive index layer is MgF2; the number of periods of the distributed Bragg reflector DBR (3) is 11, the thickness of the high refractive index layer is 60~68nm and the thickness of the low refractive index layer is 110~120nm.

2. The wavelength-tunable hybrid plasmonic micro / nano laser based on TPP and SPP according to claim 1, characterized in that, The distributed Bragg reflector DBR (3) is prepared by magnetron sputtering or electron beam evaporation deposition.

3. The wavelength-tunable hybrid plasmon micro / nano laser based on TPP and SPP according to claim 1 or 2, characterized in that, The selected silver film thickness is 32nm; the selected PMMA layer thickness is 277nm; the number of cycles of the distributed Bragg reflector DBR (3) is selected as 11, that is, the distributed Bragg reflector DBR (3) is formed by 11 pairs of TiO2 / MgF2 stacked and deposited alternately, wherein the thicknesses of TiO2 and MgF2 are 65nm and 118nm, respectively.

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