基于超表面窄带反射镜的窄线宽外腔激光器Narrow linewidth external cavity laser based on metasurface narrowband mirror
【技术领域】[Technical Field]
本发明属于激光器技术领域,更具体地,涉及一种基于超表面窄带反射镜的窄线宽外腔激光器。The invention belongs to the technical field of lasers, and more particularly, relates to a narrow line-width external cavity laser based on a super-surface narrow-band reflector.
【背景技术】【Background technique】
自1962年第一台半导体激光器问世以来,在这半个世纪中,半导体激光器产业迅速发展,随着输出功率和光束质量的不断提高,半导体激光器被广泛的应用在诸多领域之中。如激光打标、光谱研究、放大器、密集波分复用技术、固体激光器泵浦源等。此外,半导体激光器还被广泛的应用在生活领域如指示器、条形码扫描器、打印机等。Since the advent of the first semiconductor laser in 1962, the semiconductor laser industry has developed rapidly in this half century. With the continuous improvement of output power and beam quality, semiconductor lasers have been widely used in many fields. Such as laser marking, spectrum research, amplifier, dense wavelength division multiplexing technology, solid-state laser pump source, etc. In addition, semiconductor lasers are also widely used in life fields such as indicators, bar code scanners, printers, and so on.
半导体激光器具有许多独特的优势,如体积小,光电转换效率高,驱动功耗低,覆盖范围广等。但是也存在着一些严重的不足,如线宽较宽,虽然有些半导体激光器可以达到10MHz左右,但远达不到许多系统要求的理想单模窄线宽(亚kHz)的要求。外腔半导体激光器克服了普通半导体激光器线宽较宽、频率稳定性差的缺点。且它效率高、寿命长、频率稳定,可以广泛应用于光波器件测量、计量检测、水质检测、高分辨率光谱分析等领域。目前常用的外腔半导体激光器一般利用光栅结合,主要有光纤光栅、闪耀光栅、体布拉格光栅等,设计原理上类似,通过在外腔中插入分光元件,利用分光元件与腔外反馈机制来实现激光波长的调谐。光栅器件本身对于温度以及应变比较敏感,这也导致由光栅制作而成的光栅外腔半导体激光器易受外界环境影响而导致外腔系统的不稳定,进而影响输出激光的稳定性。另外基于光栅结构的半导体激光器需要复杂的沉积再生长以及高精度的光刻工艺,整体制作工艺较为繁杂。Semiconductor lasers have many unique advantages, such as small size, high photoelectric conversion efficiency, low driving power consumption, and wide coverage. However, there are also some serious shortcomings. For example, the line width is wide. Although some semiconductor lasers can reach about 10MHz, they are far from the ideal single-mode narrow linewidth (sub-kHz) requirements of many systems. External-cavity semiconductor lasers overcome the shortcomings of ordinary semiconductor lasers, such as wider line width and poor frequency stability. And it has high efficiency, long life, and stable frequency, and can be widely used in the fields of light wave device measurement, metrological detection, water quality detection, high-resolution spectral analysis, and so on. At present, the commonly used external cavity semiconductor lasers generally use grating combination, mainly fiber gratings, blazed gratings, volume Bragg gratings, etc., and their design principles are similar. By inserting a beam splitting element in the outer cavity, the beam splitting element and extra-cavity feedback mechanism are used to achieve the laser wavelength Tuning. The grating device itself is relatively sensitive to temperature and strain, which also causes the grating external cavity semiconductor laser made by the grating to be easily affected by the external environment, which leads to the instability of the external cavity system, and then affects the stability of the output laser. In addition, the semiconductor laser based on the grating structure requires complicated deposition and regrowth and high-precision lithography processes, and the overall manufacturing process is relatively complicated.
因此,解决传统的窄线宽外腔激光器装配工艺复杂、工艺容差低、对 环境波动敏感等缺陷,成为本领域的技术难题。Therefore, it has become a technical problem in the field to solve the defects of complicated assembly process, low process tolerance, and sensitivity to environmental fluctuations of the traditional narrow-line-width external cavity laser.
【发明内容】[Summary of the Invention]
针对现有技术的以上缺陷或改进需求,本发明提供了一种基于超表面窄带反射镜的窄线宽外腔激光器,其目的在于,通过超表面窄带反射镜对目标波长进行反射、对非目标波长进行透射,减小谐振的带宽,实现窄带滤波;由增益物质和超表面窄带反射镜构成谐振腔,由此解决外腔激光器线宽较宽、结构复杂、对环境波动敏感、稳定性差等技术问题。In view of the above defects or improvement needs of the prior art, the present invention provides a narrow linewidth external cavity laser based on a supersurface narrowband mirror, and the purpose thereof is to reflect a target wavelength by using a supersurface narrowband mirror and The wavelength is transmitted to reduce the resonant bandwidth and realize narrow-band filtering. The resonant cavity is composed of gain material and ultra-surface narrow-band mirror, thereby solving the technology of wide line width of external cavity laser, complex structure, sensitivity to environmental fluctuations, and poor stability. problem.
为实现上述目的,本发明提供了以下技术方案:To achieve the above objective, the present invention provides the following technical solutions:
基于超表面窄带反射镜的窄线宽外腔激光器,其特征在于,包括增益物质、准直组件和超表面窄带反射镜,其中,A narrow linewidth external cavity laser based on a metasurface narrowband mirror is characterized in that it includes a gain substance, a collimation component, and a metasurface narrowband mirror, where:
所述增益物质的一端为光出射端,用于射出信号光,该信号光经过所述准直组件准直后变为平行光垂直入射至所述超表面窄带反射镜的表面上;所述超表面窄带反射镜的表面为亚波长周期性结构的超表面;所述超表面对非目标波长进行透射和输出,对目标波长进行反射;该反射的目标波长经过所述准直组件、所述增益物质的一端入射至所述增益物质的另一端外侧;所述增益物质的另一端外侧镀有增反膜,用于作为反射镜,将入射光再次反射,经过所述准直组件入射至所述超表面上;以此方式,由所述增益物质的另一端外侧增反膜和所述超表面窄带反射镜构成谐振腔,结合所述增益物质对目标波长的光反复进行谐振放大,最终形成激射,激射光透过所述超表面输出。One end of the gain substance is a light emitting end for emitting signal light, and the signal light is collimated by the collimating component and becomes parallel light perpendicularly incident on a surface of the super-surface narrow-band reflector; The surface of the surface narrow-band mirror is a super-surface with a sub-wavelength periodic structure; the super-surface transmits and outputs non-target wavelengths, and reflects the target wavelength; the reflected target wavelength passes through the collimation component and the gain One end of the substance is incident to the outside of the other end of the gain substance; an antireflection coating is plated on the outside of the other end of the gain substance, which is used as a mirror to reflect the incident light again and is incident on the collimating component to the On the super-surface; in this way, a resonant cavity is formed by the other side of the gain material outside the antireflection film and the super-surface narrow-band mirror, and the gain material is used to repeatedly resonate and amplify the light of the target wavelength in combination with the gain material to finally form an excitation And the laser light is transmitted through the metasurface.
由增益物质发出的信号光经过准直组件垂直入射到超表面窄带反射镜的超表面上,超表面为亚波长周期性结构。对于亚波长周期性结构而言,垂直入射的光束能够激发该结构内部光场的集群性相干振荡,这种光场的局域振荡与入射光相互作用能够改变光的透射与反射特性。信号光激发超表面内部的相干震荡,使超表面窄带反射镜对满足内部振荡条件的目标波长具备高反射率,对其他非目标波长具备高透过率,并且减小反射光谐振 的带宽,进而减小谐振后透射的激光的带宽,实现窄带滤波;透射的波长直接进行输出,反射的目标波长入射至作为反射镜的增益物质的另一端外侧增反膜;由超表面窄带反射镜、增益物质的另一端外侧增反膜构成谐振腔,结合增益物质,选择激光波长的同时对其不断震荡放大,最终形成激射,激射光透过超表面输出。The signal light emitted by the gain material passes through the collimating component and is incident on the supersurface of the supersurface narrowband mirror vertically. The supersurface is a sub-wavelength periodic structure. For a sub-wavelength periodic structure, a vertically incident beam can excite a cluster of coherent oscillations of the light field inside the structure. The local oscillation of this light field interacts with the incident light and can change the transmission and reflection characteristics of the light. The signal light excites the coherent oscillation inside the metasurface, so that the metasurface narrowband mirror has a high reflectivity for the target wavelength that meets the internal oscillation conditions, a high transmittance for other non-target wavelengths, and reduces the bandwidth of the reflected light resonance. Reduce the bandwidth of the transmitted laser light after resonance to achieve narrow-band filtering; the transmitted wavelength is directly output, and the reflected target wavelength is incident on the other side of the gain material that is the gain material of the reflector; the ultra-surface narrow-band mirror and gain material The other side of the anti-reflection coating on the other side constitutes a resonant cavity. Combined with a gain substance, the laser wavelength is selected while it is continuously oscillated to amplify it. Finally, lasing is formed, and the lasing light is output through the supersurface.
优选地,所述超表面上制备有一个或多个拼接的微纳图形阵列;所述微纳图形阵列为多个相同的微纳图形周期排布构成的阵列;以此方式,通过调整超表面上单个微纳图形阵列中微纳图形的尺寸和排布周期、多个微纳图形阵列的拼接,使所述超表面仅对目标波长进行反射、对非目标波长进行透射,减小谐振的带宽,实现窄带滤波。Preferably, one or more spliced micro / nano graphic arrays are prepared on the super surface; the micro / nano graphic array is an array composed of a plurality of identical micro / nano graphic periodic arrangements; in this way, by adjusting the super surface The size and arrangement period of micro-nano patterns in a single micro-nano pattern array and the stitching of multiple micro-nano pattern arrays enable the supersurface to reflect only target wavelengths and transmit non-target wavelengths, reducing the bandwidth of resonance To achieve narrow-band filtering.
通过调整超表面上单个微纳图形阵列中微纳图形的尺寸和排布周期、多个微纳图形阵列的拼接,使超表面窄带反射镜对满足内部振荡条件的目标波长具备高反射率,对其他非目标波长具备高透过率,并且减小反射光谐振的带宽,进而减小谐振后透射的激光的带宽,实现窄带滤波。By adjusting the size and arrangement period of micro-nano patterns in a single micro-nano pattern array on the supersurface, and stitching multiple micro-nano pattern arrays, the super-surface narrow-band mirror has a high reflectivity for the target wavelength that meets the internal oscillation conditions. Other non-target wavelengths have high transmittance, and reduce the bandwidth of reflected light resonance, thereby reducing the bandwidth of laser light transmitted after resonance, and achieving narrow-band filtering.
通过在超表面结构上将一个或多个具有不同反射波长的微纳图形阵列进行拼接,使超表面窄带反射镜同时对多个波长具备高反射率,对其他波长具备高透过率,则可实现多波长外腔激光器。激光器输出的激光波长由超表面窄带反射镜的目标波长(法诺谐振峰)决定。By splicing one or more micro-nano pattern arrays with different reflection wavelengths on the super-surface structure, the super-surface narrow-band mirror can have high reflectivity for multiple wavelengths at the same time and high transmittance for other wavelengths. Implementation of a multi-wavelength external cavity laser. The laser wavelength output by the laser is determined by the target wavelength (Fano resonance) of the metasurface narrowband mirror.
优选地,上述基于超表面窄带反射镜的窄线宽外腔激光器还包括代替所述增益物质的另一端外侧增反膜作为反射镜的第二反射镜,并且所述增益物质的另一端外侧镀有增透膜、不用于作为反射镜;所述第二反射镜设置于所述增益物质的另一端外侧;以此方式,由所述第二反射镜和所述超表面窄带反射镜构成谐振腔,结合所述增益物质对目标波长的光反复进行谐振放大,最终形成激射,激射光透过所述超表面输出。Preferably, the above-mentioned narrow-line-width external cavity laser based on the super-surface narrow-band mirror further includes a second reflecting mirror that replaces the other side of the gain substance as the reflecting mirror, and the other side of the gain substance is plated outside An antireflection coating is not used as a reflector; the second reflector is disposed outside the other end of the gain substance; in this way, a resonant cavity is formed by the second reflector and the metasurface narrowband reflector , Repeatedly resonating and amplifying light of a target wavelength in combination with the gain substance, and finally forming lasing, the lasing light is output through the metasurface.
采用第二反射镜代替增益物质的另一端外侧增反膜作为反射镜,给出备选方案使本发明更易实现。A second reflecting mirror is used as a reflecting mirror instead of the other side antireflection film on the other end of the gain material, and an alternative solution is given to make the present invention easier to implement.
优选地,调整所述增益物质另一端外侧的增反膜的反射率,激射光透过所述增益物质另一端输出,不透过所述超表面输出。给出激射光输出的备选方案使本发明更易实现。Preferably, the reflectance of the anti-reflection film on the outside of the other end of the gain substance is adjusted, and the laser light is output through the other end of the gain substance and is not output through the hypersurface. The option of giving a laser light output makes the invention easier to implement.
优选地,所述增益物质的带宽覆盖所述超表面窄带反射镜的谐振波段,能够对反射光进行放大。Preferably, the bandwidth of the gain substance covers the resonance wave band of the ultra-surface narrowband mirror, and the reflected light can be amplified.
优选地,所述准直组件是单个准直透镜或多个准直透镜的组合。Preferably, the collimating component is a single collimating lens or a combination of a plurality of collimating lenses.
通过准直组件对信号光执行准直,提高了超表面窄带反射镜的调节容差,进一步提高了激光器输出的稳定性;采用多个准直透镜准直光路,进一步提高光平行性,进而提高超表面窄带反射镜的调节容差,进一步提高激光器输出的稳定性;当增益物质的输出光束平行度较好时,准直组件可以适当精简,灵活调整。The collimation of the signal light by the collimation component improves the adjustment tolerance of the ultra-surface narrow-band mirror and further improves the stability of the laser output; the use of multiple collimating lenses to collimate the optical path further improves the light parallelism, and further improves The adjustment tolerance of the super-surface narrow-band mirror further improves the stability of the laser output; when the parallelism of the output beam of the gain substance is good, the collimation component can be appropriately simplified and flexibly adjusted.
优选地,所述微纳图形阵列中的微纳图形排布为四方晶格,六方晶格或者准晶格。Preferably, the micro-nano patterns in the micro-nano pattern array are arranged as a tetragonal lattice, a hexagonal lattice or a quasi-lattice.
优选地,所述微纳图形为纳米孔、纳米柱、纳米小球、纳米环或纳米棒。以上微纳图形采用常规工艺制作即可,制作工艺简单。Preferably, the micro / nano pattern is a nanopore, a nanopillar, a nanosphere, a nanoring or a nanorod. The above micro-nano graphics can be made by conventional processes, and the manufacturing process is simple.
总体而言,通过本发明所构思的以上技术方案与现有技术相比,能够取得下列有益效果:In general, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:
1、由超表面窄带反射镜、增益物质的另一端外侧构成仅对目标波长光谐振放大的谐振腔,选择激光波长的同时对其不断震荡放大;由于激光输出波长主要由超表面窄带反射镜的反射波长(法诺谐振波长)决定,进而提高了激光器输出的稳定性;采用准直组件对信号光执行准直,提高了超表面窄带反射镜的调节容差,进一步提高了激光器输出的稳定性;1. The super-surface narrow-band mirror and the other end of the gain material form a resonant cavity that only amplifies the target wavelength light. The laser wavelength is selected and it is continuously oscillated and amplified. Because the laser output wavelength is mainly by the super-surface narrow-band mirror. The reflection wavelength (Fano resonance wavelength) is determined, thereby improving the stability of the laser output; the use of collimation components to collimate the signal light improves the adjustment tolerance of the ultra-surface narrowband mirror and further improves the stability of the laser output ;
2、本发明通过调整超表面上单个微纳图形阵列中微纳图形的尺寸和排布周期、多个微纳图形阵列的拼接,使所述超表面仅对目标波长进行反射、对非目标波长进行透射,减小谐振的带宽,实现窄带滤波;通过调节微纳 图形阵列中微纳图形的尺寸和排布周期、多个微纳图形阵列的拼接,来调节超表面窄带反射镜反射波长、法诺谐振品质因数和消光比,提高激光输出的稳定性;本发明将超表面窄带反射镜的波长选择特性应用到外腔激光器上,激光器的输出波长完全由超表面自身谐振波长决定,不受谐振腔长度影响,具有波长稳定性好、边模抑制比高、线宽窄、调节容差大、结构简单的优点;2. The present invention adjusts the size and arrangement period of micro-nano patterns in a single micro-nano pattern array on a super surface, and stitches multiple micro-nano pattern arrays, so that the super-surface reflects only target wavelengths and non-target wavelengths. Transmit, reduce the bandwidth of resonance, and realize narrow-band filtering. By adjusting the size and arrangement period of micro-nano patterns in the micro-nano pattern array and the stitching of multiple micro-nano pattern arrays, the reflection wavelength and method of the super-surface narrow-band mirror can be adjusted. The harmonic resonance quality factor and extinction ratio improve the stability of the laser output; the invention applies the wavelength selection characteristics of the super-surface narrow-band mirror to the external cavity laser, and the output wavelength of the laser is completely determined by the self-resonance wavelength of the super-surface and is not subject to resonance The effect of cavity length has the advantages of good wavelength stability, high side mode suppression ratio, narrow line width, large adjustment tolerance, and simple structure;
3、采用第二反射镜代替增益物质的另一端外侧作为反射镜,由增益物质一端、超表面窄带反射镜、增益物质的另一端外侧或第二反射镜构成仅对目标波长光谐振放大的谐振腔,选择激光波长的同时对其不断震荡放大;不同方案使本发明结构简单、制作工艺简单、更易实现;3. A second reflector is used instead of the outside of the other end of the gain material as a reflector, and the resonance of the target wavelength light is only amplified by one end of the gain material, the super-surface narrow-band reflector, the other end of the gain material, or the second reflector. Cavity, the laser wavelength is continuously selected and amplified while the wavelength of the laser is selected; different schemes make the invention simple in structure, simple in manufacturing process, and easier to implement;
4、调整所述增益物质另一端外侧增反膜的反射率,激射光透过所述增益物质另一端输出,不透过所述超表面输出;给出激射光输出的备选方案使本发明更易实现;4. Adjust the reflectance of the anti-reflection film on the other end of the gain material so that the laser light is output through the other end of the gain material and does not transmit through the supersurface; an alternative solution for the output of the laser light makes the invention Easier to implement
5、采用多个准直透镜准直光路,进一步提高光平行性,进而提高超表面窄带反射镜的调节容差,进一步提高激光器输出的稳定性;当增益物质的输出光束平行度较好时,准直系统可以适当精简。5. Use multiple collimating lenses to collimate the optical path, further improve the light parallelism, and then improve the adjustment tolerance of the super-surface narrow-band mirror, and further improve the stability of the laser output; when the parallelism of the output beam of the gain substance is good, The collimation system can be streamlined appropriately.
6、微纳图形为纳米孔、纳米柱、纳米小球、纳米环或纳米棒,采用常规工艺制作即可,制作工艺简单。6. The micro-nano pattern is a nanopore, a nano-pillar, a nano-sphere, a nano-ring or a nano-rod, which can be produced by a conventional process, and the production process is simple.
【附图说明】[Brief Description of the Drawings]
图1是本发明实施例1中基于超表面反射镜的窄线宽外腔激光器的模型;FIG. 1 is a model of a narrow-line-width external cavity laser based on a metasurface mirror in Embodiment 1 of the present invention;
图2(a)是本发明较佳实施例中超表面结构示意图;2 (a) is a schematic diagram of a supersurface structure in a preferred embodiment of the present invention;
图2(b)是本发明较佳实施例中超表面结构原理图;2 (b) is a schematic diagram of a supersurface structure in a preferred embodiment of the present invention;
图3(a)是本发明实施例2中基于超表面反射镜的窄线宽外腔激光器的模型;3 (a) is a model of a narrow-line-width external cavity laser based on a metasurface mirror in Embodiment 2 of the present invention;
图3(b)是图3(a)模型的俯视图;Figure 3 (b) is a top view of the model of Figure 3 (a);
图4是本发明实施例3中基于超表面反射镜的窄线宽外腔激光器的模型;4 is a model of a narrow-line-width external cavity laser based on a metasurface mirror in Embodiment 3 of the present invention;
图5是本发明较佳实施例中激光光谱测试简图;5 is a schematic diagram of a laser spectrum test in a preferred embodiment of the present invention;
图6是本发明较佳实施例中外腔激光器测试光谱图;6 is a test spectrum diagram of an external cavity laser in a preferred embodiment of the present invention;
图7(a)是本发明较佳实施例中超表面制作流程图一;FIG. 7 (a) is a first flowchart of making a supersurface according to a preferred embodiment of the present invention; FIG.
图7(b)是本发明较佳实施例中超表面制作流程图二;FIG. 7 (b) is a second flow chart of the method of making a supersurface in the preferred embodiment of the present invention; FIG.
图7(c)是本发明较佳实施例中超表面制作流程图三;FIG. 7 (c) is the third flowchart of making a supersurface in the preferred embodiment of the present invention; FIG.
图7(d)是本发明较佳实施例中超表面制作流程图四。FIG. 7 (d) is the fourth flowchart of the fabrication of the supersurface in the preferred embodiment of the present invention.
在所有的附图中,相同的附图标记用来表示相同的元件或结构,其中:The same reference numbers are used throughout the drawings to refer to the same elements or structures, where:
1-增益芯片 2-准直透镜 3-超表面窄带反射镜1-gain chip 2-collimating lens 3-nano-surface narrow-band mirror
4-反射镜 5-左准直透镜 6-右准直透镜4-reflector 5-left collimator lens 6-right collimator lens
7-双面抛光硅基底 8-二氧化硅 9-氮化硅7-double-sided polished silicon substrate 8-silicon dioxide 9-silicon nitride
10-光刻胶10-Photoresist
【具体实施方式】【detailed description】
为了使本发明的目的、技术方案及优点更加清楚明白,以下结合附图及实施例,对本发明进行进一步详细说明。应当理解,此处所描述的具体实施例仅仅用以解释本发明,并不用于限定本发明。此外,下面所描述的本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
实施例1Example 1
如图1所示,本实施例中窄线宽外腔激光器包括增益芯片1、准直透镜2和超表面窄带反射镜3,其中,As shown in FIG. 1, the narrow-line-width external cavity laser in this embodiment includes a gain chip 1, a collimator lens 2, and a super-surface narrow-band reflector 3.
增益芯片1作为增益物质,其调节功率方便,两端面a和b易于处理;增益芯片1在端面a镀有增反膜,提高端面a对光的反射率,端面b镀有增透膜,增加光的透光率。增益芯片1的带宽覆盖超表面窄带反射镜3的 谐振波段。The gain chip 1 is a gain substance, and its adjustment power is convenient, and the two end faces a and b are easy to handle. The gain chip 1 is plated with an antireflection coating on the end face a to improve the light reflectance of the end face a, and an antireflection coating is plated on the end face b. Light transmittance. The bandwidth of the gain chip 1 covers the resonance band of the metasurface narrowband mirror 3.
单个准直透镜2作为准直组件,便于调节。A single collimating lens 2 is used as a collimating component for easy adjustment.
超表面窄带反射镜3的表面为亚波长周期性结构的超表面,该超表面对目标波长具有高反射率,对非目标波长的光进行透射。The surface of the metasurface narrowband mirror 3 is a subsurface of a sub-wavelength periodic structure, which has a high reflectivity to a target wavelength and transmits light of a non-target wavelength.
增益芯片1发出的宽带光由b端面出射,经准直透镜2准直后变为平行光,垂直入射到超表面窄带反射镜3的超表面上,超表面对目标波长进行反射,非目标光进行透射,反射的目标波长的光先后经过准直透镜2、增益芯片端面b,进入增益芯片1后在其端面a再次反射,由端面a和超表面窄带反射镜3构成谐振腔,结合增益芯片1对目标光反复进行谐振放大,最终形成激射,激射光透过超表面输出,另外通过调整增益芯片1端面a增反膜的反射率,端面a也可以作为激光输出端。The broadband light emitted by the gain chip 1 exits from the b-end surface, collimated by the collimator lens 2, and becomes parallel light, which is incident on the metasurface of the metasurface narrowband mirror 3 vertically. The metasurface reflects the target wavelength and is not the target light. For transmission, the reflected light of the target wavelength passes through the collimator lens 2, the gain chip end face b, enters the gain chip 1, and is reflected again at the end face a. The resonance cavity is formed by the end face a and the super-surface narrowband mirror 3, and the gain chip is combined. 1 The target light is repeatedly amplified and amplified, and finally a lasing light is transmitted through the metasurface. In addition, by adjusting the end face a of the gain chip 1 to increase the reflectance of the reflective film, the end face a can also be used as a laser output end.
作为进一步优选地,超表面上制备有一个或多个拼接的微纳图形阵列;微纳图形阵列为多个相同的微纳图形周期排布构成的阵列;微纳图形是指纳米孔、纳米柱、纳米小球、纳米环或纳米棒等;一个微纳图形阵列中微纳图形可选择地排布为四方晶格,六方晶格或者准晶格等。通过调整超表面上单个微纳图形阵列中微纳图形的尺寸和排布周期、多个微纳图形阵列的拼接,使超表面仅对目标波长进行反射、对非目标波长进行透射,减小谐振的带宽,实现窄带滤波。As a further preferred method, one or more spliced micro / nano graphic arrays are prepared on the super surface; the micro / nano graphic array is an array composed of a plurality of identical micro / nano graphic periodic arrangements; the micro / nano graphic refers to nanopores, nanopillars , Nanospheres, nanorings or nanorods, etc .; the micro / nano patterns in a micro / nano pattern array can be optionally arranged as a tetragonal lattice, a hexagonal lattice or a quasi-lattice. By adjusting the size and arrangement period of micro-nano patterns in a single micro-nano pattern array on the supersurface, and stitching multiple micro-nano pattern arrays, the super-surface reflects only the target wavelength, transmits non-target wavelengths, and reduces resonance Bandwidth to achieve narrow-band filtering.
本发明将超表面结构的谐振特性应用到外腔激光器上,一是作为窄带反射镜,二是作为波长选择器;通过调整超表面结构进而选择合适的品质因数和消光比,进一步提高输出激光的稳定性。The invention applies the resonance characteristics of the super-surface structure to an external cavity laser, firstly as a narrow-band reflector and secondly as a wavelength selector; by adjusting the super-surface structure and selecting a suitable figure of merit and extinction ratio, the output laser light is further improved. stability.
如图2(a)、图2(b)所示,为超表面结构示意图和原理图,图中超表面结构制备有一个微纳图形阵列。当平行光垂直入射时,由于微纳图形阵列的集群性相干振荡,这种局域振荡会与入射光相互作用对目标波长进行反射,非目标光会透射出去。超表面结构可选择地制备一个或多个拼接的微纳图形阵列,以实现对不同目标波长的反射和窄带滤波。As shown in Fig. 2 (a) and Fig. 2 (b), there are schematic diagrams and schematic diagrams of the super-surface structure. In the figure, a micro-nano pattern array is prepared. When parallel light enters vertically, due to the cluster coherent oscillation of the micro / nano pattern array, this local oscillation will interact with the incident light to reflect the target wavelength, and non-target light will be transmitted out. The supersurface structure can optionally prepare one or more spliced micro / nano graphic arrays to achieve reflection and narrowband filtering of different target wavelengths.
实施例2Example 2
如图3(a)所示,本实施例中窄线宽外腔激光器包括增益芯片1、反射镜4和超表面窄带反射镜3,其中,As shown in FIG. 3 (a), the narrow-line-width external cavity laser in this embodiment includes a gain chip 1, a mirror 4, and a super-surface narrow-band mirror 3, where:
超表面窄带反射镜3与实施例1中相同,在此不再重复赘述。The super-surface narrow-band mirror 3 is the same as that in Embodiment 1, and is not repeated here.
增益芯片1采用实施例1中增益芯片,区别在于,本实施例中增益芯片1的端面a镀有增透膜而不是增反膜,以提高对光的透过率;端面a不作为反射镜,不对超表面窄带反射镜3反射的目标波段进行反射,而由反射镜4代替进行反射。The gain chip 1 uses the gain chip in Embodiment 1. The difference is that the end face a of the gain chip 1 in this embodiment is coated with an anti-reflection coating instead of an anti-reflection coating to improve the light transmittance; the end face a is not used as a mirror. , The target wave band reflected by the super-surface narrow-band mirror 3 is not reflected, but is reflected by the mirror 4 instead.
反射镜4对应的反射波段覆盖超表面窄带反射镜3反射的目标波段。The reflection wave band corresponding to the mirror 4 covers the target wave band reflected by the metasurface narrowband mirror 3.
增益芯片1发出的宽带光由端面b出射,出射光入射到超表面窄带反射镜3上,由于超表面窄带反射镜3上微纳结构的集群性相干振荡,这种局域振荡会与入射光相互作用对目标波长进行反射,非目标光会透射出去,反射的目标波长光先后经过增益芯片1的端面b和端面a,入射到反射镜4上,如图3(b)所示,此处反射镜4垂直于从增益芯片1端面a出射的光,由此,在反射镜4、增益芯片1、超表面窄带反射镜3之间构成一个谐振腔,其中只有垂直于反射镜以及超表面窄带反射镜的目标波长的光可以不断谐振放大,最终形成激光,激射光由超表面一端输出。The broadband light emitted by the gain chip 1 is emitted from the end face b, and the emitted light is incident on the metasurface narrowband mirror 3. Due to the cluster coherent oscillation of the micro-nano structure on the metasurface narrowband mirror 3, this local oscillation will be related to the incident light. The interaction reflects the target wavelength, and the non-target light is transmitted. The reflected target wavelength light passes through the end face b and the end face a of the gain chip 1 and is incident on the reflector 4 as shown in FIG. 3 (b). Here, The reflecting mirror 4 is perpendicular to the light emitted from the end face a of the gain chip 1, thereby forming a resonant cavity between the reflecting mirror 4, the gain chip 1, and the super-surface narrow-band mirror 3, of which only the perpendicular to the mirror and the super-surface narrow-band is formed. The light of the target wavelength of the reflector can be continuously amplified and amplified to form a laser, and the laser light is output from one end of the metasurface.
实施例3Example 3
如图4所示,本实施例中窄线宽外腔激光器包括增益芯片1、左准直透镜5、右准直透镜6和超表面窄带反射镜3,其中,As shown in FIG. 4, the narrow-line-width external cavity laser in this embodiment includes a gain chip 1, a left collimator lens 5, a right collimator lens 6, and a super-surface narrow-band mirror 3.
超表面窄带反射镜3、增益芯片1及其端面a和端面b的处理均与实施例1中相同,在此不再重复赘述。The processing of the super-surface narrow-band reflector 3, the gain chip 1, and its end faces a and b is the same as that in Embodiment 1, and details are not described herein again.
左准直透镜5和右准直透镜6为两个准直透镜,由他们组合构成准直组件对增益芯片1出射的光执行准直变为平行光。同时根据实际需要可以适当增加准直透镜的数量,以提高了超表面窄带反射镜的调节容差,进一步提高激光器输出的稳定性;The left collimating lens 5 and the right collimating lens 6 are two collimating lenses, and a combination of them is used to form a collimating component. The light emitted from the gain chip 1 is collimated to become parallel light. At the same time, according to actual needs, the number of collimating lenses can be appropriately increased to improve the adjustment tolerance of the super-surface narrow-band mirror and further improve the stability of the laser output;
增益芯片1发出的宽带光由其端面b出射,入射到左准直透镜5上,经过左准直透镜5的光汇聚于右准直透镜6的左侧焦点上,如此,光经过右准直透镜6后变为平行光;又因为采用双透镜进行准直,调节容差会增加,因此系统的稳定性会提升;由右准直透镜6出射的平行光垂直入射至超表面窄带反射镜3的超表面上,由于超表面窄带反射镜3上微纳结构的集群性相干振荡,这种局域振荡会与入射光相互作用对目标波长进行反射,非目标波长会透射出去,反射的目标波长的光先后经过右准直透镜6、左准直透镜5和增益芯片1的端面b,进入增益芯片1最后在增益芯片1的端面a反射回来,由此,在增益芯片1的端面a与左准直透镜5、右准直透镜6以及超表面之间构成谐振腔,结合增益芯片1对目标光反复进行谐振放大,最终形成激射,激射光由超表面一端输出,另外通过调整增益芯片1端面a增反膜的反射率,端面a也可以作为激光输出端。The broadband light emitted by the gain chip 1 exits from its end face b and is incident on the left collimating lens 5. The light passing through the left collimating lens 5 is converged on the left focal point of the right collimating lens 6. Thus, the light passes through the right collimating The lens 6 becomes parallel light; and because the double lens is used for collimation, the adjustment tolerance will increase, so the stability of the system will be improved; the parallel light emitted by the right collimator lens 6 will enter the hypersurface narrowband mirror 3 vertically. Due to the clustered coherent oscillation of the micro / nano structure on the hypersurface narrowband mirror 3, this local oscillation will interact with the incident light to reflect the target wavelength, the non-target wavelength will be transmitted out, and the reflected target wavelength The light passed through the right collimator lens 6, the left collimator lens 5, and the end face b of the gain chip 1, entered the gain chip 1, and finally reflected back at the end face a of the gain chip 1. Thus, the end face a of the gain chip 1 and the left A resonant cavity is formed between the collimating lens 5, the right collimating lens 6, and the metasurface. In combination with the gain chip 1, the target light is repeatedly amplified and amplified, and finally a lasing is formed. A gain chip 1 by the end face of the anti-reflection film, the end face may be used as a laser output.
进一步地,本发明实施例提供一种激光输出光谱的测定系统,用以测定本发明激光器的光谱特性。Further, an embodiment of the present invention provides a laser output spectrum measurement system for measuring the spectral characteristics of the laser of the present invention.
如图5所示,测试系统主要由窄线宽外腔激光器、聚焦透镜、3dB耦合器、光谱仪、功率计组成,其中,As shown in Figure 5, the test system is mainly composed of a narrow linewidth external cavity laser, a focusing lens, a 3dB coupler, a spectrometer, and a power meter. Among them,
窄线宽外腔激光器采用实施例1中的窄线宽外腔激光器;聚焦透镜用于收集由超表面窄带反射镜3背面透射的能量,输入到光纤中,3db耦合器的作用是将由光纤收集到的能量分为两部分,分别传输到光谱仪和功率计中,其中光谱仪用于直接观察光谱特性,功率计用于检测输出光的功率。The narrow-line-width external-cavity laser uses the narrow-line-width external-cavity laser in Example 1; the focusing lens is used to collect the energy transmitted by the back of the super-surface narrow-band reflector 3 and input into the optical fiber. The role of the 3db coupler is to collect by the optical fiber The received energy is divided into two parts, which are respectively transmitted to the spectrometer and the power meter. The spectrometer is used to directly observe the spectral characteristics, and the power meter is used to detect the power of the output light.
测试系统安装时,首先将3dB耦合器与光谱仪、功率计连接好,然后调节窄线宽外腔激光器得到输出激光,调节顺序为:When the test system is installed, first connect the 3dB coupler to the spectrometer and power meter, and then adjust the narrow-line-width external cavity laser to obtain the output laser. The adjustment sequence is:
1)在增益芯片1上加电流,调节至100mA附近,接着放入聚焦透镜,调节聚焦透镜的角度和高度,使得功率计能量最高;1) Add current to the gain chip 1 and adjust it to around 100mA, then put the focusing lens, adjust the angle and height of the focusing lens, so that the power meter has the highest energy;
2)放入准直透镜2,调节准直透镜2角度和高度,使得功率计能量最高;2) Put the collimator lens 2 and adjust the angle and height of the collimator lens 2 so that the power meter has the highest energy;
3)放入超表面窄带反射镜3,调节角度,主要是Y,Z轴的调节,同时观测光谱仪光谱,直到观测到目标波长的激射。3) Put in a super-surface narrow-band mirror 3 and adjust the angle, mainly the adjustment of the Y and Z axes, while observing the spectrometer spectrum until the lasing of the target wavelength is observed.
激射后可以通过调节电流源大小观测激光器的阈值电流,以及饱和电流;可以通过光谱仪和功率计观测激光器输出的稳定性以及输出功率的大小。After lasing, the threshold current and saturation current of the laser can be observed by adjusting the size of the current source; the stability of the laser output and the output power can be observed by a spectrometer and a power meter.
图6为光谱测试结果,其中横坐标为波长,纵坐标为光谱能量,可以看出消光比在55dB左右,品质因数1万以上。Figure 6 shows the results of the spectrum test, where the abscissa is the wavelength and the ordinate is the spectral energy. It can be seen that the extinction ratio is about 55dB and the quality factor is more than 10,000.
同样的原理对测试系统稍加调整即可对实施例2-4的窄线宽外腔激光器进行光谱测定。With the same principle, a slight adjustment of the test system can perform spectral measurement on the narrow linewidth external cavity laser of Examples 2-4.
进一步地,本发明实施例还提供一种超表面窄带反射镜的制作工艺流程,主要使用等离子体增强化学的气相沉积法(Plasma Enhanced Chemical Vapor Deposition,PECVD)沉积材料,采用电子束(Electron Beam Lithography,EBL)曝光超表面器件,最后通过感应耦合等离子体刻蚀设备(Inductively Coupled Plasma,ICP)刻蚀,得到所需的超表面结构,从而得到超表面窄带反射镜。Further, the embodiment of the present invention also provides a manufacturing process flow of a super-surface narrow-band reflector, which mainly uses Plasma Enhanced Chemical Vapor Deposition (PECVD) to deposit materials, and uses Electron Beam Lithography , EBL) exposure of the super-surface device, and finally through inductively coupled plasma etching equipment (ICP) etching to obtain the required super-surface structure, thereby obtaining a super-surface narrow-band mirror.
如图7(a)所示,采用双面抛光硅基底7,首先使用PECVD在衬底硅表面依次沉积1.6um的二氧化硅(SiO
2)8和0.58um的氮化硅(Si
3N
4)9,其中SiO
2材料作为隔离层,Si
3N
4材料作为功能层。
As shown in FIG. 7 (a), a double-sided polished silicon substrate 7 is used. First, PECVD is used to sequentially deposit 1.6 um of silicon dioxide (SiO 2 ) 8 and 0.58 um of silicon nitride (Si 3 N 4 ) 9, wherein the SiO 2 material is used as the isolation layer, and the Si 3 N 4 material is used as the functional layer.
如图7(b)所示,基片清洗烘干后,旋涂光刻胶10(优选正性光学抗蚀剂,如ZEP-520),对光刻胶进行前烘,由于正性光刻胶曝光部分显影后会溶解出去,对小面积版图而言,减少了曝光时间。As shown in FIG. 7 (b), after the substrate is cleaned and dried, a photoresist 10 (preferably a positive photoresist, such as ZEP-520) is spin-coated, and the photoresist is pre-baked. The exposed part of the glue will dissolve after development, and for a small area layout, the exposure time is reduced.
如图7(c)所示,采用EBL将版图转至光刻胶上,曝光时间约5-10min。曝光完成后,在二甲苯、异丙醇中先后进行显影、定影,之后使用后用氮气枪吹干器件表面。此时被曝光部分的光刻胶被溶解,版图结构转移至光刻胶10上。As shown in Figure 7 (c), the layout is transferred to the photoresist using EBL, and the exposure time is about 5-10min. After the exposure is completed, development and fixing are sequentially performed in xylene and isopropyl alcohol, and then the surface of the device is dried with a nitrogen gun after use. At this time, the exposed photoresist is dissolved, and the layout structure is transferred to the photoresist 10.
如图7(d)所示,采用ICP刻蚀除去部分或全部未被光刻胶保护的表 层Si
3N
4,刻蚀时间为27s,刻蚀深度约75nm,选用气体SF
6+C
4F
8。之后,采用去胶液去除表层光刻胶,最后用去离子水冲洗,氮气枪吹干器件。
As shown in Figure 7 (d), ICP etching is used to remove part or all of the surface layer Si 3 N 4 that is not protected by the photoresist. The etching time is 27s, the etching depth is about 75nm, and the gas SF 6 + C 4 F is selected. 8 . After that, the photoresist on the surface layer is removed by a degumming solution, and finally the device is rinsed with deionized water, and the device is dried by a nitrogen gun.
至此,超表面窄带反射镜制作完成。At this point, the fabrication of the super-surface narrow-band mirror is complete.
本文提出一种基于超表面结构作为窄带反射镜同时选择波长的窄带外腔激光器,简化了制作工艺,降低了激光器对外界环境的敏感度。This paper proposes a narrow-band external-cavity laser based on a super-surface structure as a narrow-band mirror, which simultaneously selects the wavelength, which simplifies the manufacturing process and reduces the sensitivity of the laser to the external environment.
本发明采用超表面窄带反射镜作为窄带反射镜和波长选择器,由超表面窄带反射镜、增益物质的另一端外侧增反膜构成仅对目标波长光谐振放大的谐振腔,选择激光波长的同时对其不断震荡放大;激光波长主要由超表面谐振波长决定,进而提高了激光器输出的稳定性;采用准直组件对信号光执行准直,提高了超表面窄带反射镜的调节容差,进一步提高了激光器输出的稳定性;通过调整超表面结构使其仅对目标波长进行反射、对非目标波长进行透射,减小谐振的带宽,实现窄带滤波;具有波长稳定性好、边模抑制比高、线宽窄、调节容差大、制作工艺简单的优点。另外将超表面结构的特性应用在外腔激光器制作上,为超表面的应用提供了一种新的思路。The present invention uses a super-surface narrow-band mirror as a narrow-band mirror and a wavelength selector. The super-surface narrow-band mirror and the other side of the gain material outside the anti-reflection film constitute a resonant cavity that only amplifies the target wavelength light. It continuously oscillates and amplifies it; the laser wavelength is mainly determined by the super-surface resonance wavelength, which improves the stability of the laser output; the use of collimation components to collimate the signal light increases the adjustment tolerance of the super-surface narrow-band mirror, and further improves The stability of the laser output is adjusted; by adjusting the supersurface structure to reflect only the target wavelength and transmit the non-target wavelength, reduce the bandwidth of resonance and achieve narrow-band filtering; it has good wavelength stability, high side mode suppression ratio, The advantages of narrow line width, large adjustment tolerance, and simple manufacturing process. In addition, the characteristics of the super-surface structure are applied to the fabrication of external cavity lasers, which provides a new idea for the application of the super-surface.
本领域的技术人员容易理解,以上所述仅为本发明的较佳实施例而已,并不用以限制本发明,凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等,均应包含在本发明的保护范围之内。Those skilled in the art can easily understand that the above description is only the preferred embodiments of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention, All should be included in the protection scope of the present invention.