Volume 49 Issue 12
Dec.  2020
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Wang Huafeng, Sun Ke, Sun Shengzhi, Qiu Jianrong. Femtosecond laser induced microstructures in diamond and applications (Invited)[J]. Infrared and Laser Engineering, 2020, 49(12): 20201057. doi: 10.3788/IRLA20201057
Citation: Wang Huafeng, Sun Ke, Sun Shengzhi, Qiu Jianrong. Femtosecond laser induced microstructures in diamond and applications (Invited)[J]. Infrared and Laser Engineering, 2020, 49(12): 20201057. doi: 10.3788/IRLA20201057

Femtosecond laser induced microstructures in diamond and applications (Invited)

doi: 10.3788/IRLA20201057
  • Received Date: 2020-10-17
  • Rev Recd Date: 2020-11-02
  • Available Online: 2021-01-14
  • Publish Date: 2020-12-25
  • For many years, silicon and germanium have been considered the suited semiconductor materials for detectors and integrated optoelectronic devices fabrication. However, compared with diamond-based devices, such tetravalent semiconductors are less resistant to radiation damage, and the devices are less stable under harsh conditions or under high-energy light radiation. In recent years, due to the excellent optical and mechanical properties, diamond has become a promising material in the application of integrated photonics, sensors, and quantum optics etc. The laser-induced microstructures of diamond represents a powerful tool used for the development optical 3D-contacts devices all-carbon detectors graphite resistors on diamond, as well as the realization of single photon source. The physical mechanisms of femtosecond laser induced color center, graphitization and refractive index change in diamond were demonstrated. Based on this, the applications of the femtosecond laser induced micro-nano structures in diamond for single photon source, sensor and optical waveguide were introduced. Then, the future developing tendency in this field was prospected.
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Femtosecond laser induced microstructures in diamond and applications (Invited)

doi: 10.3788/IRLA20201057
  • 1. Ningbo University of Finance & Economics, Ningbo 315175, China
  • 2. College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
  • 3. The Research Institute of Advanced Technologies, Ningbo University, Ningbo 315211, China

Abstract: For many years, silicon and germanium have been considered the suited semiconductor materials for detectors and integrated optoelectronic devices fabrication. However, compared with diamond-based devices, such tetravalent semiconductors are less resistant to radiation damage, and the devices are less stable under harsh conditions or under high-energy light radiation. In recent years, due to the excellent optical and mechanical properties, diamond has become a promising material in the application of integrated photonics, sensors, and quantum optics etc. The laser-induced microstructures of diamond represents a powerful tool used for the development optical 3D-contacts devices all-carbon detectors graphite resistors on diamond, as well as the realization of single photon source. The physical mechanisms of femtosecond laser induced color center, graphitization and refractive index change in diamond were demonstrated. Based on this, the applications of the femtosecond laser induced micro-nano structures in diamond for single photon source, sensor and optical waveguide were introduced. Then, the future developing tendency in this field was prospected.

    • 金刚石晶体中,碳原子以SP3杂化轨道与另外四个碳原子形成共价键,构成四面体,所有价电子都参与了共价键的形成。金刚石不仅硬度大、熔点高、高度透明,而且不导电。金刚石广泛应用于电子器械、机械加工、石油勘探、医疗等领域。随着量子信息科学技术的蓬勃发展,金刚石由于其出色的光电性能、化学稳定性以及可在室温下通过光学和磁共振方法实现自旋极化和调控的特性,有望应用于固态量子系统中进行如磁场、电场、应力、压强、温度以及核自旋等微小物理信号的灵敏探测[1-3]。在高精度机械传感方面,由于其高导热性而具有低热弹性损耗,使得机械谐振器在高频率下工作而不受显著阻尼的影响[4]。此外,金刚石提供的光学透明度是自然形成的材料中最宽的,从UV区域(~225 nm)延伸到太赫兹(THz)频率,甚至微波区域(~8000 μm),在这些波段具有低群速度色散,因此适用于制备集成光子学器件[5]。近年来对金刚石光学活性缺陷中心的研究表明,在金刚石中有500种以上色心,它们的发射波长覆盖紫外到近红外波段[6-7],色心表现出高度稳定的单光子荧光并提供一个可控的相干电子自旋,且具有长期的稳定性和低声子态密度从而导致低的电子-声子耦合。而且金刚石的德拜温度极高,这使得其声子诱导的相位变化概率很低[8-9]。因此,金刚石色心已经成为不需要在低温条件下操作的固态单光子发射器的唯一候选。

      在实际应用中,由于金刚石材料本身的超高硬度、高折射率和低电导率等特点,利用常规方法很难在合适的位置精确形成设计的微纳结构。要利用金刚石进行光子器件和探测器的制造,例如在金刚石内部直写石墨导电回路等三维微纳结构以及图案化金刚石色心,发展一种高效可控的在其内部制备微纳米结构的方法是必须的。最近,有研究利用各向异性的等离子体斜角度蚀刻金刚石,这种角度蚀刻方法可在大块单晶金刚石表面制造独立的纳米尺度组件,包括纳米机械谐振器、光波导、光子晶体和微盘腔等[10-11]。但与其他方法一样,其制备的几何结构仅限于在金刚石表面[10, 12]。另外,传统的高能射线辐照等色心制备方法很难实现在金刚石内部任意位置精确诱导色心,限制了色心与微纳光学结构集成的空间自由度。离子注入法以唯一能实现指定位置亚微米级精度色心分布的方法被广泛研究,但受电子束能量和金刚石表面损伤阈值的限制,这种方法只适合在金刚石表面和较浅层位置诱导色心,且后续热处理工序会对金刚石内微纳结构的光学性能带来负面影响[13]

      相对于上述方法而言,飞秒激光直写技术对材料的加工基于多光子吸收等非线性过程,可在表层无损的情况下聚焦到金刚石内部,并突破衍射极限诱导产生高空间分辨的复杂的三维微纳结构[14]。通过调整加工参数,采用飞秒激光可以在金刚石实现包含内部和表面色心、折射率变化、微孔洞和微裂纹等多种微结构的精准诱导,并通过各种微结构的组合制备多种功能性光电器件。

    • 金刚石色心体系中比较常见的有镍-氮色心(NE8)、SiV色心和氮空位色心(NV)[15],以及钴、镍、铬、硼、氙、氧等杂质原子相关的色心[16]。这些色心的激发态寿命、荧光光谱的宽度以及零声子线发射概率有一定差别。对这些色心体系的研究丰富了金刚石色心在单光子源产生、量子操控、量子探测等方面的技术应用[2, 8, 17-18]。近年来,制备金刚石色心的主要方法可分为离子注入、外延掺杂生长、电子辐照、激光写入和热退火等[19-22]

      氮空位色心天然存在于块状金刚石、同质外延生长金刚石和金刚石纳米晶体中,是金刚石晶格中的一个点缺陷,它由最近邻的一对氮原子和一个晶格空位组成。当金刚石碳晶格中的两个相邻位置被氮和空位所取代时就出现了氮空位色心[23],如图1所示。它们既可以作为单个孤立缺陷出现,也可以作为高密度集成出现。在金刚石合成过程中,通常通过在这种材料中掺杂氮不纯净物或将氮离子注入金刚石来产生色心[24]。但该方法不能在指定位置形成色心,为了有效地对单个色心进行精确空间上的诱导形成,一些新的技术被开发用于制备空间位置可选择的金刚石NV色心。

      Figure 1.  Schematic diagram of the crystal structure of diamond with NV center (carbon atoms represented in black, nitrogen atom shown in yellow, and the vacancy shown in white)[23]

      利用飞秒激光辐照在金刚石表面形成色心的基本原理为:当飞秒激光脉冲聚焦在金刚石表面附近,激光脉冲具有超高的峰值功率,在空气中传播时会形成强电场,强电场电离空气产生大量电子,并加速电子沿着激光传播方向高速行进,高速电子轰击金刚石晶格可产生晶格空穴,空穴与氮原子等杂质原子在随后的热处理过程中结合产生色心[25]

      该方法最初是由华东师范大学精密光谱科学与技术国家重点实验室的Zeng[26]等于2013年提出的。他们将飞秒激光聚焦于金刚石样品表面1~2 μm处,利用强红外激光脉冲在激光聚焦交点处高温高压作用下产生的电子束溅射在金刚石样品表面上,然后将金刚石置于680 ℃的空气氛围中加热5 min进行氧化,在激光辐照区域形成了NV色心,制备流程如图2所示。虽然这个方法能实现亚微米级的空间精度色心分布,但是所需的能量随着色心制备深度的增加而递增,在样品深处诱导色心所需的高能量会在激光辐照部位造成损伤,并降低诱导所得色心的光谱特性。2019年,该团队[27]进一步通过飞秒激光辐照包覆有硅纳涂层的金刚石表面,在退火后制备获得了SiV色心,为制作近表面SiV色心开创了一种有价值的方法。

      Figure 2.  (a) Experimental setup for the femtosecond laser illumination on a diamond sample; (b) Illuminated diamond sample by femtosecond pulsed laser with different illumination time; (c) Same diamond sample after slow oxidation[26]

      近年来,如何精确、无损地在金刚石内部诱导高质量的色心成为很多学者关注的研究热点。将金刚石内部的色心集成到微纳光学结构是实现金刚石色心体系的器件化的必由之路。

    • 当飞秒激光与晶体材料相互作用时,一般是产生热激子,然后通过弛豫过程将能量传递给晶格[28]。在金刚石晶体中,热激子的产生一般是通过多光子电离过程产生的,而热激子产生晶格损伤可能会导致更高的非线性,单位时间内吸收光子的数量直接影响激光辐照区域的作用结果。飞秒激光辐照不仅能在金刚石表面生成色心,在其内部也能可控制备出高质量氮空位色心。2017年,牛津大学的Chen[29]等人在电子级金刚石样品内深度50 μm处实现了高质量的NV色心写入。利用飞秒激光微加工系统中的像差校正实现精确控制诱导结构在金刚石晶体中的位置,定位精度在像平面内可达200 nm。通过改变脉冲能量Ep (16.0~61.8 nJ),辐照区域经过退火产生色心的成功概率高达45±15%,制备所得的单个NV色心在低温下显示出稳定相干的光学跃迁。

      上述制备色心的方法,需要在飞秒激光辐照后对样品金刚石做长达数小时的热处理,以驱使激光诱导产生的空穴在金刚石内扩散,进而与氮原子结合产生NV色心。由于热处理中空穴的扩散是随机的,因此用这些方法在金刚石内指定位置制备色心的空间精度和成功概率不高。为解决这一问题,2019年,Chen[30]等人提出在单脉冲飞秒激光诱导产生空穴后,用一束聚焦的低能量飞秒激光脉冲辐照色心诱导部位以取代对样品的整体热处理,如图3(a)3(b)所示,该方法可以选择性地的在金刚石内指定空间引导空穴扩散,提高色心制备的空间精度和成功率,实验中制备的色心定位精度最高可达35 nm。

      Figure 3.  Schematic of the laser-writing process. A single seed pulse is used to generate vacancies in the crystal, followed by a pulse train at lower energy to locally anneal the diamond[30]

    • 在玻璃材料中,利用超短脉冲激光照射的方法可以改变照射区域材料的折射率,使三维波导写入成为可能。而在金刚石晶体中,激光与金刚石的相互作用通常会产生由于晶格的损伤导致辐照区域折射率的下降,一般伴随周围区域材料的折射率在应力的作用下有所上升。为了进一步探究飞秒激光辐照区域折射率变化的影响,2016年,意大利米兰理工大学的Sotillo[31]等人对辐照区域的拉曼光谱进行了分析。如图4所示,未辐照区域的具有以1332 cm−1为中心的典型的拉曼峰,典型的最大半高宽约为2.3 cm−1,激光辐照区域的拉曼光谱显示,在1333 cm−1处金刚石峰的强度降低了约15%,表明金刚石晶体结构的无序度增加(图4(b))。

      Figure 4.  (a) Transverse optical microscope image of single laser-induced track written with 500 kHz repetition rate. 50 mW average power and 0.5 mm/s scan speed; (b) μ-Raman spectra (532 nm excitation wavelength) at four different vertical positions inside the modifcation. "Out" refers to a spectrum taken outside the track. The spectra have been normalized to the diamond peak to show the change in the relative intensity of the G-peak inside the structure[31]

      2017年,Sotillo[32]等人进一步对不同重复频率激光照射下的辐照区域进行了µ-Raman光谱测试。随着脉冲频率的降低辐照区域金刚石的拉曼峰值出现蓝移,这是压应力增加导致的。由图5可知,在500 kHz重复频率下,拉曼峰的半高宽约为2 cm−1,表明辐照区域金刚石晶体结构得到了保留。随着重复频率的降低,拉曼峰半高宽增加,在重复频率为5 kHz时达到3 cm−1的值,表明晶体结构产生轻微的无序。此外,由谱图观测的峰的偏移在1~ 4 cm−1之间变动,而在500 kHz条件下,观测到的偏移保持在1.5 cm −1左右,表明在低重复频率激光辐照区域的应力更大,更不均匀[5]

      Figure 5.  Shift of the Raman diamond peak at the center for different repetition rates [32]

      之后,他们使用重复频率500 kHz高重频飞秒激光辐照金刚石内部探讨了折射率变化和应力分布的关系[33]。通过微区拉曼光谱分析计算获得了应力分布和折射率变化。结果表明,在平行于晶面[001]方向上,两条线形成的波导的中心区域的折射率最大,如图6(a)所示,这与中心区域应力较大的结果相吻合(如图6(b)所示)。

      Figure 6.  (a) Map of the refractive index profile; (b) Measured vertical line profile of τ1 and τ2 at the center of the waveguide[33]

    • 金刚石在近红外波段是透明的。然而,紧密聚焦的超短脉冲激光束提供了多光子吸收所需的高电场。当功率超过阈值时,局部金刚石结构被转化为非晶碳和石墨。日本京都大学的Shimotsuma[34]等利用1 kHz的飞秒激光在金刚石内部制备了直径为18 μm的点阵,并发现激光作用区存在石墨化现象。2009年,瑞士伯尔尼大学的Neff[21]等利用1 kHz、140 fs的飞秒激光在金刚石内部制备了连续的石墨导电线。但金刚石的高折射率导致激光焦点存在较大球差,该方法制备所得的石墨线在沿着焦点方向存在明显变形。为改善球差引起的石墨线变形,2011年,英国牛津大学的Simmonds[35]课题组在飞秒激光直写系统中引入由SLM和DM组成的双自适应光学装置,在金刚石内部制作了紧凑的石墨结构并校正与深度相关的像差,该系统允许制造微米尺寸结构深度大于200 μm,如图7所示,相差校正后直写的石墨化图案精度提升。

      Figure 7.  Top (xy) and side (xz) view of the date fabricated in diamond at a depth of 80 μm. (a) Without aberration correction; (b) Employing the dual adaptive optics system. The laser beam was incident along the z direction, the scale bar represents 5 μm[35]

      此外,直写过程中飞秒激光的频率对辐照区域石墨化也有着较大的影响。Sotillo[31]等人利用拉曼测试的方法探究了激光重复频率与辐照区域石墨化的关系,如图8所示,在1575 cm−1处出现G峰,在1360 cm−1处出现D峰,这表明金刚石sp3键合转变为sp2,辐照区域出现非晶碳相和石墨相,当激光重复频率增加到500 kHz时,未见2D和D+G峰,这表明辐照区域的石墨化减小。更多的相关研究证明低重复频率的飞秒激光会更多的诱导辐照区域的石墨化,而高重复频率的飞秒激光在辐照区域内则更容易诱导产生非晶碳[3, 36]

      Figure 8.  μ-Raman spectra (normalized to the G-peak) in the center of modification tracks at repetition rates of 5 kHz, 25 kHz and 500 kHz, with pulse energy held constant (800 nJ) to produce a similar size modification at each repetition rate[31]

      2017年,英国牛津大学的Booth[37]利用飞秒激光直写的方法在金刚石内部制备了亚微米级线宽的3D石墨导电线,其传导率比以前报道的用超短脉冲激光制作的导线大一个数量级,电阻率达到0.022 Ω/cm,接近多晶石墨,且最小写入导电纳米线宽度小于400 nm。利用该项技术可在金刚石内部直写三维微米级石墨导电结构。这种金刚石内部的石墨化加工具有广泛应用,如全碳金刚石辐射探测器、金属介质光子晶体等[38-39]

    • 氮空位金刚石色心由于优异的性能,在传感和量子信息处理方面有着巨大的应用潜力。NV色心的电子大部分集中在空位上,结合形成自旋三重态,即使在室温下也可以用532 nm激光激发。为了充分挖掘金刚石NVs的潜力,在金刚石内部制备光波导是量子信息处理不可避免的技术挑战。在金刚石晶体中利用激光辐照产生折射率变化制作波导的策略是激光直写两行相隔几微米的平行刻痕。当间距合适时,波导的芯层位于平行刻痕的中心,这类波导被称为双线型II型波导。Sotillo[31]等人在2016年首次对这种双线波导的导光模式和损耗进行了系统的研究。首先,他们利用飞秒激光在深度为50 μm的单晶金刚石内部写入了间距为13 μm的双线波导。如图9所示,波导在横向扫描输入时表现出单模场。但在垂直扫描时,在不同的深度表现出三种不同的模场,最低损耗的模场位于双线波导之间,然后使用单模光纤对波导进行耦合,测得最低传输损耗模场下波导的传输损耗为16 dB/cm。

      Figure 9.  Transverse microscope view of type II waveguide in diamond along with near field mode profile (λ=635 nm). An arrow indicates the position of the mode[31]

      金刚石从中红外到THz波段具有较低的群速度色散,2018年,Bharadwaj[40]等人在单晶金刚石中利用飞秒激光制备双线型中红外波导,并在其通过波长为2.4 μm的光对其导光性能进行了分析。图10测得通过波导后光的脉冲宽度(绿色曲线)为99 fs (计算得群速度色散为|190| fs2/mm),略小于通过相同长度的金刚石晶体的116 fs (计算得群速度色散为|275| fs2/mm)。波导结构对金刚石本身的群速度色散影响非常小,进一步表明了激光直写金刚石波导技术应用于金刚石集成化中红外光电器件的潜在应用。

      Figure 10.  Interferometric autocorrelations of the 150 MHz pulse trains generated by the KLM Cr:ZnSe at the input facet of the diamond crystal (a); At the waveguide output (b); After propagation through bulk diamond crystal (c). The red, blue, and green curves in the autocorrelations correspond to the intensity autocorrelation profile

      除单晶金刚石外,使用飞秒激光也可以在多晶金刚石内直写光波导。Hanafi[41]等人利用飞秒激光在多晶金刚石内部写入了Ⅲ型凹陷包层波导。写入的波导截面是由一圈激光直写轨迹构成的,其几何形状为圆形,直径分别为20 μm和25 μm,如图11所示。他们探究了使用激光脉冲能量和波导直径对金刚石波导的导模分布和传输损耗的影响,获得了最小传输损耗34.8 dB/cm。随着飞秒激光直写技术的发展,研究者们开始探究在金刚石内直写比波导更复杂的光学微纳结构,如:Y型分束器[42]、布拉格光栅和波导的集成制备[43]等。

      Figure 11.  End-facet of the type III depressed cladding waveguides, over layered with the measured guided near-field mode profile for a core diameter of 20 µm and 25 µm[41]

    • 随着量子通讯技术等形式的量子信息处理技术高速发展,基于信息处理过程中单光子编码的需要,理想的单光子源中光子的数目在每次触发时仅激发一个光子,高效可靠的单光子源已经成为了量子信息处理的一个重要应用基础。

      2016年,Chen[29]等人首次利用能量为15~40 nJ、波长为790 nm、脉宽300 fs的飞秒激光在金刚石内部产生了Frenkel缺陷,在退火后获得了单NV色心。由于使用了空间光调制器校正了相差,其定位精度能达到100 nm。光子自相关测试结果表明,单色心的典型数据在图12(a)中显示,对全部的色心进行光子自相关测试后,他们发现二阶自相关函数g(2)(0)的值大致分为三个区间(图12(b)),一部分色心的g(2)(0) < 0.32,另一部分的g(2)(0) < 0.65,这分别归因于单色心和双色心的存在。少数色心显示g(2)(0)值介于0.65~0.9之间,他们认为这是由于该区域有三个色心的存在。

      Figure 12.  (a) Histogram showing g(2)(δt) from a single NV centre;(b) Histogram of g(2)(0) for the different laser processing sites, allowing the identification of sites of single, double and triple NV centre generation[29]

      在此基础上,Chen[30]等使用了激光辐照退火的方法诱导色心形成,并在这个过程中通过将自定义扫描共聚焦光致发光(PL)显微镜集成到激光书写系统中,实时监测该过程中的测量荧光反馈。在整个退火过程中,没有读取到来自电荷中性态NV0的荧光,也未探测到其他荧光信号如孤立空位(GR1)或扩展缺陷(B band),如图13(a)所示。此外,在对形成的25个辐照点进行光子自相关测试后发现,有24个辐照点的g(2)(0) <0.2,如图13(b)所示,表明这24个位点只包含一个NV中心,利用该技术方案形成单色心的概率达到96%。

      Figure 13.  (a) NV color center fluorescence spectrum and fluorescence monitor band; (b) Histogram of g(2)(0) values for the array; (Inset) typical g(2)(τ) dataset corrected for background signal from the bulk crystal[30]

      相对于NV色心,SiV色心的线宽更窄(5 nm内)远小于NV色心的100 nm,用作单光子源编制量子密钥时,其信噪比较高。Rong等人将飞秒激光聚焦在涂覆纳米硅球的高纯度金刚石表面。在高峰值功率飞秒激光的作用下,硅原子被电离并植入到金刚石中的同时产生了空位缺陷。在850 °C真空退火1 h后,辐照区域陨石坑周围形成SiV色心。色心的荧光光谱在737 nm处呈现出典型的强零声子线,其最小二阶自相关函数g(2)(0)为0.07,如图14所示,显示出单SiV色心特征。

      Figure 14.  Second-order autocorrelation functions of the PL from SiV A and B with background noise correction, revealing single SiV centers[27]

    • 硅和锗多年来一直被认为是制造辐射和粒子探测器最好的半导体基材。但这种四价半导体在极端条件下,例如辐射和高能粒子激发的环境中,其稳定性较差。金刚石探测器由于其具有优异的抗辐射和极高的电阻率以及较低的介电常数带来的相对较低的噪声水平被研究者们青睐。

      2017年,Booth[37]等人使用球差校正的飞秒激光加工系统在金刚石内部直写了具有方形和六角形几何形状单元格的用于收集电荷和跟踪带电粒子探测器。他们使用波长为790 nm、重复频率为1 kHz的飞秒激光通过空间光调器(SLM)在金刚石内部写入石墨导电线,直径约为2 μm的导电线被排列成正方形、长方形和六角形单元(图15)。探测器的性能是通过质子微束轰击探测器产生的离子束感应电荷和时间分辨离子束感应电流来检测的,方形和六角形探测单元在40 V的偏置电压下都显示出完全的电荷收集,六角形单元显示出大约比方形单元少25%的电荷分配。电荷分配特性对于带电粒子跟踪非常重要,电荷分配有助于提高跟踪分辨率,而对于定量测定带电粒子的探测器,电荷分配则不利于对带电粒子进行定量分析。

      Figure 15.  Optical images of the detector. The metallization and readout strips are shown in gold. The three areas are: left, planar array; middle, 3D phantom array; right, 3D array. The detector connection scheme with bias voltage (HV) contacted to the back side, and channel 1 (CH1) and channel 2 (CH2) connected to the current amplifiers is shown. The areas enclosed in the dashed line correspond to the measurement locations[37]

      与探测器内直写平面电极结构不同,2018年Girolami[44]等人在金刚石中利用飞秒激光直写诱导了柱状电极阵列用于捕获探测电荷,如图15所示。他们利用工作波长为1030 nm、重复频率为200 kHz、脉宽为400 fs的飞秒激光在金刚石背面直写了14条平行石墨带,然后在金刚石正面位于石墨带上方沿激光束轴远离透镜以相同的脉冲能量直写6个高度为400 μm石墨柱(图16)。在捕获性能不受影响的前提下,质子束辐照下电荷收集效率可达94%。

      Figure 16.  Optical microscopy image (taken from the lateral surface of the sample) of a group of three pillars belonging to the same strip[44]

    • 由于金刚石出色的性能及其色心体系对于量子科学、超灵敏探测领域的深远意义,近年来,国内外众多研究小组竞相开展基于超快激光在金刚石内部微纳加工的理论和实验研究,并取得一系列成果。飞秒激光诱导金刚石微纳结构的可分为飞秒在金刚石内部诱导色心、折射率变化、石墨化,这些结构在单光子产生、光波导、探测等方面具有重要的应用前景。尽管飞秒激光直诱导金刚石微纳结构的应用前景广阔,但还亟需解决一些关键的科学和技术问题:其一,在飞秒激光直写金刚石波导的过程中需要研究损耗形成的机理,开拓降低传输损耗和耦合损耗以及弯曲损耗的技术;其二,优化色心制备技术,精准无损诱导色心的形成,降低后续热处理对其色心性能的影响;其三,进一步拓展飞秒激光诱导金刚石结构在量子操控以及精密探测等领域的应用。

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