阅读说明：本技术 一种波长可切换的定向单模片上微型激光器实现方法 (Method for realizing directional single-mode on-chip micro laser with switchable wavelength ) 是由 金立敏 陈献 巫云开 刘伟松 于 2020-12-29 设计创作，主要内容包括：本发明提供了一种波长可切换的定向单模片上微型激光器实现方法,即以镧系元素掺杂的核-壳-壳上转换纳米颗粒为光学增益介质,制备定向单模片上微型激光器。本发明的有益效果是：实现了在不同光激励下具有波长动态可切换功能的定向单模激光输出,波长位移长达300纳米。(The invention provides a method for realizing a wavelength-switchable directional single-mode on-chip micro laser, which is to prepare the directional single-mode on-chip micro laser by taking lanthanide-doped core-shell up-conversion nano particles as an optical gain medium. The invention has the beneficial effects that: the directional single-mode laser with the wavelength dynamic switchable function under different light excitations is output, and the wavelength displacement reaches 300 nanometers.)

1. A method for realizing a directional single-mode on-chip micro laser with switchable wavelength is characterized by comprising the following steps: the lanthanide-doped core-shell up-conversion nano particles are used as an optical gain medium to prepare the directional single-mode on-chip micro laser.

2. The method of claim 1 for implementing a wavelength switchable directional single-mode on-chip micro laser, comprising: the core-shell up-conversion nano-particles are Nd-Yb-Ho-Tm composite doped multi-shell rare earth up-conversion nano-particles.

3. The method of claim 2, wherein the method comprises: the Nd-Yb-Ho-Tm composite doped multi-shell rare earth up-conversion nanoparticles are synthesized by a coprecipitation epitaxial growth method, and can generate different multicolor fluorescence outputs under the excitation of 980nm and 808nm light.

4. The method of claim 3, wherein the method comprises: and preparing the directional single-mode on-chip micro laser taking the Nd-Yb-Ho-Tm composite doped multi-shell rare earth upconversion nanoparticles as an optical gain medium by spin coating and a standard photoetching process.

Technical Field

The invention relates to a micro laser, in particular to a method for realizing a micro laser on a directional single-mode chip with switchable wavelength.

Background

The coherent light source has the advantages of low noise, good monochromaticity and high output power, and plays an important role in the fields of high-flux chemical/biological sensing, color laser display, on-chip optical communication, calculation and the like. In recent years, with the increasing demands for precision and information density in highly integrated photonic devices, higher requirements are put forward on micro lasers, which requires a micro coherent light source, i.e. a multi-color single-mode nano laser, capable of simultaneously realizing broadband output and high spectral purity. Due to the lack of an efficient mode selection mechanism for multiple bands, today's micro-lasers are often limited in their multi-color, multi-mode output, greatly limiting their practical applications.

Several technologies have been successfully developed to achieve multi-color micro-nano lasers, including semiconductor lasers integrating multiple layers of gain media with different band gaps on a single laser device, organic photoelectric material doped microsphere lasers, whispering gallery mode micro-lasers using inorganic lanthanide up-conversion nanocrystals as gain media, and organic/inorganic perovskite hybrid micro-lasers. The wavelength of light emitted by semiconductor lasers depends on the basic band gap of each layer of material, but due to spatial hole burning effect, self-absorption effect, cavity nonuniformity and the fixed band structure of the semiconductor, such lasers mostly operate in multiple modes and the wavelength of the laser is difficult to tune in a wide range, and the existence of competing modes can cause spurious signals and temporal fluctuation, which severely limits their practical application in various photonic devices. Organic dye and lanthanide doped inorganic up-conversion nanocrystals show great potential for gain region tuning (from ultraviolet to near infrared) due to their abundant energy levels and customizable optical properties. However, such self-assembled micro lasers cannot be mass produced, are not compatible with CMOS technology, are difficult to implement on-chip devices, and face serious challenges in application. In addition, the lead halide perovskite laser has very low laser threshold and high quantum yield, and the chemical quantity dependence tunability of the luminescent color of the lead halide perovskite laser makes the lead halide perovskite an ideal material for developing nano photoelectrons, but the material is very sensitive to oxygen, humidity and light irradiation, and the further development and application of the material are greatly limited by the material life of the lead halide perovskite. In addition, compared with organic dyes and inorganic rare earth doped nanocrystalline materials, the perovskite material has a limited adjustable range and cannot meet the requirements of multicolor detection and multiband communication application.

In the conventional laser system, single longitudinal mode laser light is mostly generated by adding an intracavity dispersive element, a fabry-perot, a filter, and the like, but these techniques are difficult to implement on a chip device. Recently, in order to further realize on-chip integrated single-mode micro-nano laser, researchers have proposed the following strategies: (1) the resonant modes are manipulated by reducing the size of the microcavity. The manufacturing process tends to be complex and can significantly increase the threshold of the laser. (2) The optical pumping condition is modulated in a real-time coupling and modulation mode, a distributed feedback grating mode and a space modulation mode. However, most of these single-mode lasers only work in one gain region or are limited to a specific device, and cannot simultaneously act on multiple wave bands, and the design difficulty is large, and they are often not suitable for multi-color single-mode micro-nano lasers. (3) This is achieved by an astronomical-time symmetric microcavity. Researchers apply the micro-ring cavity in the design of a coupled laser element, and a single-mode laser is obtained by regulating and controlling loss and gain. This method can improve the gain of a specific mode and maintain stable single-mode operation in a wider pumping range. However, the limitation of this mechanism is that it depends on the electron beam etching preparation method, and it is difficult to implement single-mode laser for a larger laser resonator, and it is not able to form effective unidirectional emission, which is not beneficial to on-chip integration application.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a method for realizing a wavelength-switchable directional single-mode on-chip micro laser.

The invention provides a method for realizing a directional single-mode on-chip micro laser with switchable wavelength, namely, a lanthanide-doped multi-shell up-conversion nano particle is taken as an optical gain medium to prepare the directional single-mode on-chip micro laser.

As a further improvement of the invention, the core-shell up-conversion nano-particles are Nd-Yb-Ho-Tm composite doped multi-shell rare earth up-conversion nano-particles.

As a further improvement of the invention, the Nd-Yb-Ho-Tm composite doped multi-shell rare earth up-conversion nanoparticles are synthesized by a coprecipitation epitaxial growth method, and the Nd-Yb-Ho-Tm composite doped multi-shell rare earth up-conversion nanoparticles can generate different multicolor fluorescence outputs under the excitation of 980nm and 808nm light.

As a further improvement of the invention, the nano-particles are combined with a quasi-space-time symmetrical structure cavity through spin coating and a standard photoetching process to prepare the directional single-mode on-chip micro laser taking the Nd-Yb-Ho-Tm composite doped multi-shell rare earth upconversion nano-particles as an optical gain medium.

The invention has the beneficial effects that: by the scheme, directional single-mode laser output with a wavelength switchable function under different light excitations is realized.

Drawings

FIG. 1 is an exemplary diagram of the structure of the multi-shell nanocrystals of the present invention and their fluorescence spectra under 980nm and 808nm laser pumping.

FIG. 2 is an exemplary diagram of the device structure design and the mode selection principle based on theoretical calculation.

FIG. 3 is a demonstration chart of the optical characteristics of the device of the present invention.

FIG. 4 is an experimental demonstration of single mode laser directional output of the device of the present invention.

FIG. 5 is a graph illustrating the uniformity of device performance according to the present invention.

Detailed Description

The invention is further described with reference to the following description and embodiments in conjunction with the accompanying drawings.

The invention provides a strategy for realizing a directional single-mode on-chip micro laser with a wavelength dynamic switchable function, namely, lanthanide-doped up-conversion nanocrystals are integrated on a cavity with a quasi-space-time symmetric structure, and the output direction, wavelength and mode of emitted light are accurately controllable through an external coupling mechanism. Therefore, the on-chip micro laser takes the multi-shell up-conversion nano particles as an optical gain medium and takes the coupling double discs with certain size difference as a resonant cavity, and realizes directional single-mode laser output with wavelength switchable function under different light excitation conditions. In addition, by tuning the rare earth doped ion species, the method can realize directional single-mode laser output with randomly tunable light-emitting wavelength (ultraviolet-visible-near infrared).

The design method of the micro single-mode laser device comprises the following steps:

1. by a coprecipitation epitaxial growth method, Nd-Yb-Ho-Tm composite doped multi-shell rare earth upconversion nanoparticles are synthesized, and the particles can generate two groups of different multicolor fluorescence outputs under the excitation of 980nm light and 808nm light. The upconversion particles can be used as an effective gain medium of a single-mode laser, and the fluorescence spectrums of the upconversion particles under different optical excitation conditions are shown in the figure 1.

FIG. 1 is an exemplary diagram of the structure of a multi-shell nanocrystal and its fluorescence spectra under 980nm (top) and 808nm (bottom) laser pumping.

2. And carrying out simulation calculation on the structure of the miniature single-mode laser device. Fig. 2a shows the device structure design, and this type of device consists of two tangential uniformly coupled microdisks, where the selectively pumped microdisks act as gain cavities and the unpumped microdisks act as loss cavities. We have performed simulation calculations on the mode selection mechanism of the structure, as shown in fig. 2b and 2 c. In the calculation, we fixed the radius of the left (lossy) resonator to 5.27 μm and continuously adjusted the radius of the right (lossy) resonator to change the size deviation of the two coupled microdisks. Based on the different mode spacing and outcoupling mechanisms of the two microdisks, under asymmetric excitation, a PM with a given size difference exhibits a single-mode laser output at 647.0nm (347.2nm) under 808nm (980nm) optical excitation. Other competing peaks and modes will be effectively suppressed to enhance single mode laser performance.

Fig. 2 is a schematic diagram of the structural design of the miniature single-mode laser device and the mode selection principle based on theoretical calculation. Wherein, (a) is based on the device structure design diagram of the up-conversion nanocrystalline doping in step 1; simulation calculation chart of mode modulation under the excitation condition of (b)980nm and (c)808nm right pump light. In theoretical calculations, the two coupling cavities have diameters of 5.27 μm (left microdisk) and 6.76 μm (right microdisk), respectively.

3. By spin coating and standard photoetching process, lanthanide doped up-conversion nano-crystal is integrated in a quasi-space-time symmetrical structure cavity to prepare the on-chip micro photonic device taking the up-conversion nano-particles in the step 1 as the gain medium, and experimental demonstration is carried out on the optical characteristics of the on-chip micro photonic device. The results show that by externally controlling the pump wavelength (808/980nm), the device can support dynamic switching of dual wavelength single mode lasers (647.0/347.2nm) over a wide range (-300 nm) with an extinction ratio as high as 11dB (fig. 3) under asymmetric pumping. Moreover, the device can maintain directional (180 degrees in phi in fig. 4) single-mode laser output in a wide range of pump power, and the divergence angle of the single-mode laser is within 30 degrees.

FIG. 3 is a demonstration chart of the optical characteristics of the device of the present invention. Comprises laser spectrograms of the device under the conditions of (a)808nm and (c)980nm right side cavity pumping and different powers, and corresponding (b, d) main emission peak threshold curve and extinction ratio data.

FIG. 4 is an experimental demonstration of single mode laser directional output of the device of the present invention.

In consideration of the manufacturing error problem caused by the standard photolithography technique, we have conducted test characterization on the uniformity of the photonic device, and the result is shown in fig. 5. The randomly selected device arrays all showed single mode lasing characteristics with only slight fluctuations in lasing wavelength and threshold. I.e. the single mode laser device is not sensitive to fluctuations in parameters of the lithographic process.

FIG. 5 is a graph illustrating the uniformity of device performance. The normalized laser emission spectra of different PM devices under the conditions of (a)808nm and (b)980nm right cavity pumping, and the corresponding (c) single-mode laser wavelength and (d) threshold variation graph.

In addition, the experimental method for the directional single-mode on-chip micro laser with switchable wavelength, which is provided by the invention, adopts silicon dioxide as a substrate material, is compatible with the traditional CMOS process, can be produced in a large scale, and can be applied to the fields of integrated optoelectronic circuits, optical communication, optical sensing and the like.

The method for realizing the directional single-mode on-chip micro laser with switchable wavelength has the following advantages that:

(1) a single-mode laser device based on rare earth up-conversion nanocrystalline is provided, and the design is simple and understandable.

(2) The random tunability of the gain interval and the luminous color of the rare earth doped up-conversion nanocrystal can be realized through stoichiometric doping and structural design.

(3) Enhanced single-mode laser emission can be obtained under a large range of pump power, and the extinction ratio is up to 11 dB.

(4) The output can be oriented, and the on-chip unit can be easily integrated with other on-chip units.

(5) Under the regulation and control of external light excitation, the micro laser output on a single-mode chip with dynamically switchable wavelength can be obtained.

(6) The preparation method can be prepared by a standard photoetching process, is insensitive to parameter fluctuation of the photoetching process, has low manufacturing cost and can be prepared in a large scale.

(7) Compatible with CMOS processes.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.