高功率可见光至近红外波段超连续谱光源研究进展 下载: 864次特邀综述【增强内容出版】
Supercontinuum (SC) has experienced a boom in recent decades because of its rich spectral compositions and laser characteristics. At present, the studies of SC mainly focus on power scaling, spectrum extension, and spectrum flatness improvement, among which power scaling enables abundant potential applications, such as photoelectric countermeasures, optical coherence tomography, and hyperspectral lidars.
In the photoelectric countermeasure system, a high-power broadband source is employed to suppress and disturb enemy equipment. For example, the AN/AAQ-24(V) directional infrared countermeasure system jointly developed by the United States and Britain has the function of laser jamming, and the corresponding jamming range covers the entire near-infrared waveband. In the equipment of optical coherence tomography, the material sample is scanned by a broadband source, thus achieving the reconstruction of its two-dimensional or three-dimensional image. Scanning resolution, speed, and sensitivity are three key performance parameters in this equipment, in which the scanning sensitivity can be improved by a high-power source, and the axial resolution can be enhanced by a broadband source. With these factors considered, a high-power SC source is an appropriate choice. In the hyperspectral lidar system, the active hyperspectral detection covering broadband wavelength is attractive in long-range target identification. It has been reported that the active hyperspectral detection of diffusion target has a measurement range of several hundred meters and requires the utilization of quite expensive instruments to produce and detect infrared laser radiation. The laser power is one of the main factors to determine the measurement range limit in this system. The high-power SC source has great application prospects in remote hyperspectral sensing and lidar performance enhancement due to its unique characteristics, such as good direction, broadband wavelength range, and high spectral intensity.
We review three major schemes generating high-power visible to near-infrared SC on the main oscillating power amplification (MOPA) structure, random fiber laser structure, and multichannel incoherent combination. Specifically, in the MOPA structure scheme, there are two SC generation schemes according to the generated waveband. One is adopting a MOPA structure combined with a photonic crystal fiber (PCF) or a graded-index multimode fiber (GRINMMF) to achieve a visible SC output. Some typical PCFs for high-power SC generation are also introduced (Fig. 2). The other is that the near-infrared SC generates directly from a fiber amplifier. For the SC generation scheme in a random fiber laser, several typically experimental structures are reviewed in detail. In the multichannel incoherent combination scheme, the broadband power combinations of visible SC and near-infrared SC are listed respectively. The advantages and disadvantages of these schemes and their future development potential are comprehensively analyzed.
The visible SC output power reaches 300 W based on the MOPA structure scheme, the near-infrared SC output power has reached 3 kW based on the scheme of random fiber laser, and the emergence of new fibers and schemes brings new energy for the development of high-power SC sources.
In terms of high-power visible SC, PCF is the main nonlinear medium and the corresponding studies focus on its structure design. However, the mode field diameter of PCF is small, which means it has less potential for further SC output power scaling. With the further development of the GRINMMF, this fiber with a large core size, beam self-cleaning effect, and unique mechanism of short-wave expansion can promote the further development of high-power visible SC. At present, the generated SC spectral properties of GRINMMF are poor compared with those of PCF. Believing in the future that the SC output power and spectral performance based on GRINMMF can be further improved by optimizing the refractive index curve, doping concentration, and fiber structure. In addition, most of the reported high-power visible SC is achieved by the MOPA structure scheme, and the scheme of multichannel incoherent combination can also scale the visible SC output power effectively, which can be further improved by optimizing the design of the broadband power combiner in the future.
For high-power near-infrared SC, the MOPA structure scheme is complex, but it can provide high pump peak power under the premise of ensuring the average pump power, and the generated spectral performance of SC is excellent. For the scheme of the random fiber laser, the generated SC structure is simple with high obtained SC output power, which also needs to achieve more development theoretically and experimentally in the future. The scheme of multichannel incoherent combination has the potential to break the limit of SC output power in the single fiber, but the current development is relatively slow due to the small market demand at home and abroad. However, when the output SC power of the single fiber is close to the limit in the future, the scheme will show its advantages.
We select some representative studies of high-power visible to near-infrared SC at home and abroad in terms of the above three schemes and focus on demonstrating the research progress of the National University of Defense Technology in recent years. With the improvement in the fiber drawing technology and semiconductor laser output power, and the gradual application of SC sources in photoelectric countermeasures, optical coherence tomography, and hyperspectral lidars, high-power SC sources can be further developed.
1 引言
超连续谱光谱,又被称为“终极白光”[1],是一种新型光源,由于其兼具宽光谱特性和单色激光光源的高亮度、高空间相干等特点,在近二十多年里得到了极大的发展。超连续谱的产生通常是使用一个短脉冲激光去泵浦一段非线性介质,在多种非线性效应(例如孤子分裂、受激拉曼散射、四波混频、自相位调制和交叉相位调制等)和介质色散的综合影响下,使光谱得到极大展宽的现象[2-5]。
用于超连续谱产生的非线性介质可以分为固体、气体和液体[6-8],早期在这些非线性介质中实现宽带超连续谱的产生需要极高的峰值功率且产生的光束质量相对较差。光纤作为一种新型非线性介质,可以将光束缚在一个较小的纤芯尺寸里从而获得较强的光与物质相互作用,随着光纤损耗的降低以及光纤拉制工艺的提升,尤其是光子晶体光纤(PCF)的诞生,使得光纤成为产生超连续谱的理想介质。目前,基于光纤超连续谱产生的研究热点主要集中在光谱的长波和短波拓展、光谱平坦度的改善、噪声的降低以及功率的提升这几个方面[9-12],其中功率的提升是超连续谱光源发展的重要研究热点。
高功率超连续谱光源在对光谱和功率有较高要求的光电对抗、光学相干层析和高光谱激光雷达等领域具有重要的应用前景[13-16]。在光电对抗中[13],需要一个宽带的高功率激光光源对敌方设备进行压制和干扰。例如,由美英多方联合研制的AN/AAQ-24(V)定向红外对抗系统具有激光干扰功能,干扰波长覆盖了整个近红外波段;在光学相干层析中[15-16],通常需要一个宽带光源对材料样品进行扫描从而重构该材料的二维或者三维图像。分辨率、速度和灵敏度是光学相干层析中最重要的三个指标,高功率超连续谱光源较高的功率可以提高系统灵敏度,较宽的光谱可以提高轴向分辨率;在高光谱激光雷达中[14],宽带光谱区域的主动高光谱探测对于目标的远程识别具有很大的吸引力。有报道称,扩散目标的主动高光谱探测具有几百米的测量范围,需要使用相当昂贵的仪器来产生和探测红外辐射[17-18],其中光功率是决定激光雷达(光探测和测距)系统中测量范围极限的主要因素之一。高功率超连续谱光源由于其方向性好、波长覆盖范围宽和光谱强度高,在远程高光谱传感和激光雷达的性能提升方面具有巨大的应用前景。
本文课题组在文献[19-21]中已经对超连续谱的技术方案以及中红外3~5 μm波段超连续谱光源的研究进展进行了综述,本文聚焦近几年在可见光至近红外波段比较有代表性的高功率超连续谱光源的研究成果,重点介绍了国防科技大学近几年在该领域的研究进展。在该波段中用于高功率超连续谱产生的介质主要是石英光纤,对于近红外波段(800~2500 nm)而言,常规的石英光纤即可满足该波段超连续谱的产生;而对于可见光(400~800 nm)而言,需要对石英光纤进行一定的设计从而获得合适的短波拓展。目前用于产生高功率可见光至近红外波段超连续谱光源的主要方案有三种,本文对这三种方案的研究进展和优缺点以及未来的发展潜力进行了分析与总结。
2 高功率可见光至近红外波段超连续谱光源研究进展
2.1 基于主振荡功率放大结构产生高功率超连续谱方案的研究进展
主振荡功率放大(MOPA)结构是光纤激光器用来提升功率的一种典型结构,一般由一个种子激光器和多级光纤放大器组成[22-23]。基于MOPA结构的高功率超连续谱激光光源通常先由多级光纤放大器对脉冲种子进行功率放大,然后再去泵浦一段非线性光纤产生超连续谱[24-26]。PCF由于其高非线性和独特的色散调控能力,被广泛用于产生可见光至近红外波段的超连续谱光源中[27]。然而,为了能实现超连续谱短波部分有效的增强,PCF的纤芯尺寸通常被设计得非常小,这使得它本身难以承受较高的功率以及它与泵浦光纤激光器的尾纤之间存在着模场失配。因此,研究者们开始采用多芯PCF[28]、级联PCF[29]以及长拉锥PCF[30]等方法在取得合适的短波拓展的同时增加其有效模场面积。
2018年,本文课题组齐雪等[28]采用一个放大的1016 nm脉冲激光泵浦源和一段七芯PCF用于产生高功率可见光超连续谱,
图 1. 基于MOPA结构的七芯PCF高功率可见光超连续谱产生实验装置图[28]
Fig. 1. Experimental setup diagram of high power visible supercontinuum generation in a piece of seven-core PCF based on MOPA structure[28]
图 2. 几种PCF的截面图。(a)七芯PCF[28];(b)~(c)级联PCF[29];(d)~(f)长拉锥PCF[30]
Fig. 2. Cross section images of several PCFs. (a) Seven-core PCF[28]; (b)-(c) cascaded PCFs[29]; (d)-(f) long-tapered PCFs[30]
由于PCF的模场直径比较小,基于PCF和MOPA结构的超连续谱方案在提升超连续谱功率方面总是有限的。相对而言,多模光纤具有更高的功率承受能力。相比于阶跃折射率多模光纤而言,渐变折射率多模光纤(GRINMMF)由于具有独特性能在近几年备受关注。首先,GRINMMF具有较低的克尔自清洁的阈值,这是因为其周期性振荡引起的周期性折射率光栅将更多的能量从高阶模式转换为基阶模式[31-33]。在超连续谱产生方面,其克尔效应和拉曼效应的共同作用能实现高斯光束输出[34]。其次,对于在正常色散区传播的高峰值泵浦脉冲而言,非线性折射率光栅将在可见光和近红外区域产生一系列较强的准相位匹配四波混频(又称几何参数不稳定性,GPI)边带[35]。这些特性使得GRINMMF可以支持高亮度可见光超连续谱产生。
基于GRINMMF超连续谱的首次报道是通过级联拉曼效应实现的,美国威斯康星大学Pourbeyram等[36]通过在一段GRINMMF中注入一个532 nm的脉冲获得了光谱覆盖532~1750 nm的超连续谱输出。随着GRINMMF中的GPI效应在2016被首次实验报道[35],研究者们发现,通过采用1 μm波段的高峰值脉冲光去泵浦GRINMMF,可见光波段会产生一系列的分立峰。利用该效应,研究者们通过采用高峰值的泵浦激光器在该光纤中实现了可以覆盖到可见光波段的超连续谱输出[34,37]。上述报道的泵浦激光耦合进光纤的方式均为空间光耦合,直至2022年才首次实现全光纤化[38]。在GRINMMF中,短波拓展的宽度与泵浦峰值功率成正相关[37]。为了在该光纤中获得高功率宽带的可见光超连续谱输出,需要同时提高泵浦的平均功率和峰值功率,因此需要对泵浦系统进行优化设计。2023年,中国科学院西安光学精密机械研究所张挺团队[39]通过对系统进行设计,在基于一段四模的GRINMMF中获得了30 W的超连续谱输出,光谱覆盖400~2400 nm。本文课题组从2022年开始研究基于该光纤的全光纤化可见光超连续谱功率提升[40]。
图 3. 基于GRINMMF的40 W可见光超连续谱产生[40]。(a)实验装置图;(b)光谱随泵浦功率的演化图(横坐标为频率);(c)最终输出的光谱,其中插图分别为730、620、532、470 nm波长和超连续谱总的近场光斑图
Fig. 3. 40 W visible supercontinuum generation based on GRINMMF[40]. (a) Experimental setup; (b) spectral evolution with pump power using frequency as x-coordinate; (c) final output spectrum. Insets show near-field beam profiles of total and filtered supercontinuum at wavelengths of 730, 620, 532, and 470 nm, respectively
图 4. 基于GRINMMF的204 W 可见光超连续谱产生[40]。(a)实验装置图;(b)最终输出的光谱,其中插图分别为730 nm和620 nm波长以及超连续谱总的近场光斑图
Fig. 4. 204 W visible supercontinuum generation based on GRINMMF[40]. (a) Experimental setup; (b) final output spectrum. Insets show near-field beam profiles of total and filtered supercontinuum at wavelengths of 730 nm and 620 nm, respectively
可见光波段超连续谱的产生通常需要特殊的光纤,而对于高功率近红外波段超连续谱产生而言,最有效的一种方法是采用光纤放大器直接输出超连续谱。该方法不存在泵浦光纤与非线性光纤熔接困难的问题。基于光纤放大器的单波长光纤激光器早已突破了10 kW[41],因此基于光纤放大器直接输出超连续谱的方案在功率提升方面极具潜力。该方案在2007被首次提出[42],随后功率陆续被提升到了70 W和200 W,对应的光谱范围分别为1064~1700 nm和1064~2200 nm[43-44]。在这些文献中,功率提升和光谱展宽均在增益光纤中实现,这给增益光纤带来了巨大的热负载,使得功率提升越来越困难。2023年,本文课题组[45]通过优化方案,将近红外超连续谱光源的输出功率进一步提升到了714 W,光谱范围为690~2350 nm,这是基于该方案目前公开报道的最高的功率水平和最宽的光谱范围,实验方案如
图 5. 基于光纤放大器直接输出714 W近红外超连续谱[45]。(a)实验装置图;(b)不同长度(1、20、35、50 m)下的最优超连续谱输出和(c)超连续谱输出功率随泵浦功率的演化
Fig. 5. Direct output of 714 W near-infrared supercontinuum based on fiber amplifier[45]. (a) Experimental setup; (b) optimal supercontinuum output and (c) supercontinuum output power versus pump power under different fiber lengths of 1, 20, 35, and 50 m
从上述几个比较有代表性的进展来看,对于PCF输出高功率可见光波段的超连续谱而言,优化设计PCF的结构参数仍是目前最有效的方法。然而,PCF与泵浦激光器尾纤的模场失配带来的热负载,以及PCF较小的纤芯直径是该方案进一步功率提升的限制。对于GRINMMF而言,其特性非常适合高功率可见光波段超连续谱产生,由于该种光纤仍处于起步阶段,所以功率提升和短波拓展水平目前还没有达到PCF输出超连续谱方案的水平,但该方案极具潜力,将来通过设计GRINMMF的折射率曲线、结构和掺杂浓度以及对泵浦光源的优化,有望实现更短波长、更高功率的可见光波段超连续谱输出。对于高功率近红外波段超连续谱而言,光纤放大器直接输出超连续谱仍然是首选方案,后续的发展除了进一步优化其输出光谱特性外,还应该聚焦在主放大器的热管理以及光纤长度、泵浦功率、种子源参数等这些影响因素的综合考量上面。
2.2 基于随机光纤激光器结构直接产生高功率超连续谱方案的研究进展
不同于传统的光纤激光器通过光学谐振腔来控制输出激光的特性,随机光纤激光器输出的激光不依赖于谐振腔,它是通过无序增益介质中的多次散射而形成随机分布式反馈,当反馈增益大于损耗时,实现激光输出。这种无谐振腔的光纤随机激光器具有结构更加简单、噪声更低、稳定性更好等优点[46]。2009年,随机光纤激光器被首次报道[47],随后便得到了广泛的关注。其中随机光纤激光器结构直接输出超连续谱方案继承了随机光纤激光器的优点,近几年来得到了快速发展。
2018年,电子科技大学饶云江团队的马瑞等[48]首次对基于随机光纤激光器结构输出超连续谱进行了报道,实验结构如
图 6. 基于半开腔随机光纤激光器的超连续谱产生[48]。(a)结构示意图;(b)输出光谱随泵浦功率的演化图
Fig. 6. Supercontinuum generation based on random fiber laser with half-open cavity[48]. (a) Structure diagram; (b) output spectra evolution with pump power
随后研究者们采用了各种方法对泵浦激光器进行功率提升。2018年,印度纳米科学研究所Arun等[50]采用1117 nm的掺镱光纤激光器并将泵浦功率提高到了100 W,将光纤光栅的点反馈更换成平角的端面宽带反馈(反射率约4%),将被动光纤更换成2 km SMF28e,实验结构如
图 7. 基于半开腔随机光纤激光器的34 W超连续谱产生[50]。(a)结构示意图;(b)输出光谱
Fig. 7. 34 W supercontinuum generation based on random fiber laser with half-open cavity[50]. (a) Structure diagram; (b) output spectrum
图 8. 基于双泵浦波长在随机光纤激光器中产生70 W超连续谱[51]。(a)结构示意图;(b)输出光谱
Fig. 8. 70 W supercontinuum generation in random fiber laser with two pump wavelengths[51]. (a) Structure diagram; (b) output spectrum
图 9. 基于光纤放大器在半开腔随机光纤激光器中产生130 W超连续谱[52]。(a)结构示意图;(b)输出光谱
Fig. 9. 130 W supercontinuum generation in random fiber laser with half-open cavity based on fiber amplifier[52]. (a) Structure diagram; (b) output spectrum
上述半开腔结构的随机光纤激光器输出超连续谱的功率提升均受限于波分复用器(WDM)的高功率承受能力。因此,2022年,清华大学肖起榕团队[53]摒弃了WDM的使用,并提出了一种多波长泵浦的全开腔随机光纤激光器结构,实验结构如
图 10. 全开腔随机光纤激光器中3 kW超连续谱产生[53]。(a)结构示意图;(b)输出光谱随着输出功率的演化
Fig. 10. 3 kW supercontinuum generation in random fiber laser with full-open cavity[53]. (a) Structure diagram; (b) output spectral evolution with output power
从2019年开始,本文课题组对基于随机光纤激光器结构输出超连续谱方案也进行了一系列的研究,旨在一个更简单、更高效的结构中实现宽带高功率超连续谱输出。2019年,本文课题组陈兰剑等[54]提出了一种新颖的随机光纤激光器结构,如
图 11. 半开腔随机光纤激光器中的超连续谱产生[54]。(a)结构示意图;(b)输出光谱随着泵浦功率的演化图
Fig. 11. Supercontinuum generation in random fiber laser with half-open cavity[54]. (a) Structure diagram; (b) output spectral evolution with pump power
为了进一步改善其光谱宽度和平坦度,2020年,本文课题组何九如等[56]将GDF更换为一段PCF,得益于PCF卓越的非线性光谱拓展能力和有效的随机分布式反馈,最终获得了光谱覆盖400~2300 nm的宽带平坦可见光至近红外波段超连续谱输出,这是首次报道的基于PCF随机光纤激光器输出超连续谱,光谱随功率的演化如
图 12. 基于PCF的半开腔随机光纤激光器输出超连续谱随泵浦功率的演化[56]
Fig. 12. Output supercontinuum generated in random fiber laser with half-open cavity based on PCF versus pump power[56]
图 13. 基于保偏与非保偏半开腔随机光纤激光器输出超连续谱的对比图[57]
Fig. 13. Comparison of supercontinuum generation in random fiber laser with half-open cavity with and without polarization maintaining[57]
图 14. 基于光纤端反馈的半开腔随机光纤激光器的289 W超连续谱产生[58]。(a)结构示意图;(b)输出光谱随着输出功率的光谱演化
Fig. 14. 289 W supercontinuum generation in random fiber laser with half-open cavity based on fiber end feedback[58]. (a) Structure diagram; (b) output spectral evolution with output power
从上述比较有代表性的文献报道中可以看出,虽然该方案从首次报道到现在只有四五年时间,但在输出超连续谱功率提升方面得到了快速发展并实现了巨大突破。基于WDM器件的半开腔随机光纤激光器输出超连续谱的功率提升受限于该器件的高功率承受能力。通过摒弃WDM,在一个放大的多波长全开腔随机光纤激光器中(两个振荡器种子+一级放大器)实现了高达3 kW的超连续谱激光输出,但该结构相对于随机光纤激光器方案中的其他结构而言稍显复杂。基于平角的半开腔反馈结构简单,功率提升效果显著,但光谱性能有待进一步优化。
2.3 基于多路非相干合成产生高功率超连续谱方案的研究进展
由于受热负载、非线性效应等因素的限制,单根光纤输出的激光功率存在上限。为了获得更高功率的光纤激光输出,对中等功率的光纤激光光束进行合成是一个有效的解决方案。不同于单波长的功率合束,超连续谱的功率合束要求超宽带的光能够高效率地通过,因此该方案实现高功率全光纤超连续谱的关键在于宽谱功率合束器件。商业化的单波长合束器功率早已达到了20 kW[59],因此该方案相对于单路超连续谱的功率提升具有输出更高功率的潜力。
2015年,本文课题组周航等[60]使用3×1宽带光纤功率合束器实现了输出功率为202.2 W的近红外超连续谱输出,光谱范围为1060~1900 nm,合束效率高达96%。输入光纤纤芯和包层尺寸为30/125 μm,数值孔径为0.08,输出光纤纤芯和包层尺寸为100/260 μm,数值孔径为0.2,光纤合束器结构如
图 15. 近红外超连续谱的功率合束[60]。(a)合束器示意图;(b)模拟的不同波长处的传输效率与拉锥长度之间的关系
Fig. 15. Power combination of near-infrared supercontinuum[60]. (a) Schematic of combiner; (b) simulated relationship between transmission efficiency and length of taper at different wavelengths
2022年,北京工业大学孙畅团队[62]通过设计一个7×1的超连续谱光纤合束器实现了143.4 W高功率白光超连续谱输出,光谱范围为450~1700 nm,合束效率高达97.4%。基于绝热锥变和亮度守恒准则,对于单根输入拉锥光纤而言,只有当拉锥长度大于模拟的临界锥区长度时,其传输的损耗才相对比较低。从
图 16. 不同波长处的临界拉锥长度和拉锥比之间的关系[62]
Fig. 16. Relationships between critical taper length and taper ratio at different wavelengths[62]
由上述几个比较有代表性的文献报道来看,相对于近红外超连续谱功率合束而言,可见光超连续谱功率合束在合束器制作方面会更有优势,因此该方案更有利于可见光超连续谱的功率提升。目前报道的可见光超连续谱合束功率较低的原因可能有两点:1)单路可见光超连续谱输出功率较低,当单路采用PCF获得可见光超连续谱时,PCF在后续熔接到合束器上也存在着一定的困难;2)目前报道的单路可见光超连续谱光谱覆盖范围是从可见光到近红外波段,长波处较高的耦合损耗将会降低宽带合束器的合束效率。今后可以通过优化单路超连续谱的可见光功率占比来进一步提高可见光超连续谱的功率合束效率。
3 总结与展望
高功率可见光至近红外波段超连续谱光源在近几年的时间里得到了快速的发展,基于MOPA结构的可见光超连续谱输出功率已经突破300 W,基于随机光纤激光器结构直接输出近红外超连续谱的功率已经突破3 kW,新型光纤和新方案的涌现为高功率超连续谱的发展注入了新的活力。
对于高功率可见光超连续谱而言,非线性光纤结构的优化设计仍然是其主旋律。目前,PCF仍然是高功率可见光超连续谱产生的主要非线性介质。尽管PCF的模场直径和结构一直在优化,相对而言,其模场直径仍然较小,严重制约着其输出超连续谱功率的进一步提升。随着GRINMMF的进一步发展,相信这种具有较大纤芯尺寸、光束自清洁效应和独特的短波拓展机制的光纤能推动高功率可见光超连续谱的进一步发展。目前该光纤仍处于起步发展阶段,其产生的可见光超连续谱暂时比不上基于PCF输出超连续谱方案的效果。未来可以通过对该光纤的折射率曲线、掺杂浓度以及结构进行优化设计以及改进泵浦光源来进一步提升其输出超连续谱的功率和光谱性能。此外,目前报道的高功率可见光超连续谱大多数是基于MOPA结构实现的,而多路非相干合成方案在可见光超连续谱功率提升方面也极具潜力,未来可以通过优化设计宽带功率合束器,进一步提升输出可见光超连续谱的功率水平。
对于高功率近红外超连续谱而言,基于MOPA结构输出近红外超连续谱功率方案尽管结构较为复杂,但在保证泵浦平均功率的前提下能提供较高的泵浦峰值功率,产生超连续谱的光谱性能较好;而基于随机光纤激光器结构直接输出超连续谱的方案,其结构简单,产生的超连续谱输出功率较高,在单路的超连续谱光源功率提升中最具潜力。由于该方案目前还处于起步阶段,有些内在的物理机理尚未完全清晰,相信未来该方案能够在理论和实验上实现更大的发展和突破;对于多路非相干合成方案而言,该方案有着突破超连续谱输出功率极限的潜力,但由于市场需求较小以及国内外投入的科研力量偏少,导致该方案目前发展相对较为缓慢,但未来当单路光纤输出超连续谱的功率接近极限时,该方案是进一步打破输出功率天花板的重要手段。
本文就上述三种技术方案挑选了国内外一些有代表性的研究成果进行了介绍,并重点介绍了近几年国防科技大学在高功率超连续谱方面的研究进展。随着光纤拉制工艺水平的提升以及半导体激光器输出功率的提升,以及超连续谱光源在光电对抗、光学相干层析成像和高光谱激光雷达等领域的推广应用,相信未来高功率超连续谱光源的输出功率水平会持续提升,与单波长高功率光纤激光器的差距会越来越小。
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Article Outline
江丽, 宋锐, 侯静, 陈胜平, 张斌, 杨林永, 宋家鑫, 杨未强, 韩凯. 高功率可见光至近红外波段超连续谱光源研究进展[J]. 光学学报, 2023, 43(17): 1719001. Li Jiang, Rui Song, Jing Hou, Shengping Chen, Bin Zhang, Linyong Yang, Jiaxin Song, Weiqiang Yang, Kai Han. Research Progress of High-Power Visible to Near-Infrared Supercontinuum Source[J]. Acta Optica Sinica, 2023, 43(17): 1719001.