光电工程

Port number	1	2	3	4	5	6	7	8	9
Splitting ratio at TE polarization	0.83	0.98	0.91	0.72	1.00	0.68	0.67	0.75	0.71
Splitting ratio at TM polarization	0.96	0.81	0.72	0.64	0.75	0.73	1.00	0.87	0.65

Port number

Splitting ratio at TE polarization

0.83

0.98

0.91

0.72

1.00

0.68

0.67

0.75

0.71

Splitting ratio at TM polarization

0.96

0.81

0.72

0.64

0.75

0.73

1.00

0.87

0.65

Port number	1	2	3	4	5	6	7	8	9
Splitting ratio at TE polarization	0.83	0.98	0.91	0.72	1.00	0.68	0.67	0.75	0.71
Splitting ratio at TM polarization	0.96	0.81	0.72	0.64	0.75	0.73	1.00	0.87	0.65

Port number

Splitting ratio at TE polarization

0.83

0.98

0.91

0.72

1.00

0.68

0.67

0.75

0.71

Splitting ratio at TM polarization

0.96

0.81

0.72

0.64

0.75

0.73

1.00

0.87

0.65

基于SLM的飞秒激光多焦点纵向直写高效制备玻璃光波导

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白雪 , 宋杨 , 任莹莹 ^*^,^*

光电工程 | 科研论文 2026,53(7): 260102-1

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光电工程 |科研论文 2026 , 53 (7) : 260102 -1

基于SLM的飞秒激光多焦点纵向直写高效制备玻璃光波导

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任莹莹(1985-)，女，教授，博士生导师，主要从事超快激光微纳加工、离子束材料改性、晶体材料光波导、波导激光等方面的研究。E-mail：ryywly@sdnu.edu.cn ryywly@sdnu.edu.cn

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白雪, 宋杨, 任莹莹^*^,^*

作者信息

山东师范大学物理与光电学院，山东省光场调控物理及应用重点实验室，山东济南 250358

通讯作者:

任莹莹，ryywly@sdnu.edu.cn

作者简介:

作者贡献

白雪：文献调研，进行数据处理，论文写作与修改；宋杨：文献调研，实验设计，论文初稿写作，实验系统搭建，实验数据采集；任莹莹：指导论文选题、论文方法设计。

白雪(2003-)，女，硕士研究生，主要从事飞秒激光微纳加工的研究。E-mail：18856844714@163.com 18856844714@163.com

宋杨(2001-)，男，硕士研究生，主要从事飞秒激光微纳加工的研究。E-mail：2023025705@stu.sdnu.edu.cn 2023025705@stu.sdnu.edu.cn

Efficient fabrication of optical waveguides in glass via slm-based multi-foci femtosecond laser longitudinal writing

Xue Bai, Yang Song, Yingying Ren

Affiliations

Shandong Provincial Key Laboratory of Light Field Manipulation Physics and Application, School of Physics and Electronics, Shandong Normal University, Jinan, Shandong 250358, China

Corresponding Author:

ryywly@sdnu.edu.cn

出版时间: 2026-07-25 doi: 10.12086/oee.2026.260102

文章导航

摘要

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为解决传统飞秒激光横向逐线直写光波导存在的加工效率低、截面易畸变、偏振敏感性强等问题，本文提出一种基于空间光调制器(spatial light modulator，SLM)的纵向飞秒激光多焦点直写策略。通过GSW算法设计多焦点阵列全息图，将多焦点阵列轴向与样品纵向运动方向重合，实现光波导的纵向并行高效制备。在石英玻璃内成功制备出2×2、3×3、4×4规模的I型光波导阵列及轨迹数8~16可调的环形包层光波导。所制备波导截面呈近似圆形，4×4的I型波导阵列在横电 (transverse electric, TE)和横磁(transverse magnetic, TM)偏振下，单条波导损耗最低可达0.1 dB/cm和0.2 dB/cm，展示了偏振无关的传输特性；包层光波导在任意偏振下均实现了良好的单模传输。基于该技术，通过SLM实时切换全息图，一步式完成“包层光波导输入端-I型波导阵列输出端”级联的1×9分束器集成制备，器件能够实现任意偏振分光，插入损耗低、分光均匀性优良。该方法兼具纵向直写的高对称性优势与多焦点并行加工的高效性，简化了复杂光子器件的制备流程，为高性能光子集成器件的快速制备提供了新方案。

关键词

飞秒激光加工 / 多焦点 / 光波导 / 玻璃

Abstract

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Objective

Femtosecond laser direct writing has emerged as a powerful tool for fabricating three-dimensional photonic circuits inside transparent materials. However, conventional transverse writing geometry suffers from aberration-induced cross-sectional distortion, resulting in pronounced polarization sensitivity of the inscribed waveguides. Moreover, the single-focus point-by-point scanning strategy severely limits fabrication throughput when dealing with large-scale waveguide arrays or complex integrated structures. This work aims to develop a high-efficiency, polarization-insensitive waveguide fabrication strategy that simultaneously addresses the symmetry issue of transverse writing and the throughput bottleneck of serial scanning.

Methods

A longitudinal femtosecond-laser multi-focus writing (LFLMW) technique based on a reflective phase-only spatial light modulator (SLM) was proposed. The SLM was loaded with computer-generated holograms designed by the GSW algorithm to convert a single incident beam into programmable multi-focus arrays at the focal plane of the objective lens. The sample was translated parallel to the laser propagation direction, ensuring that the axial direction of the multi-focus array coincided with the sample scanning direction. An optical system incorporating a 1030 nm, 300 fs, 76 kHz femtosecond laser amplifier, a 4f imaging system, and a 20× objective (NA = 0.4) was employed. Fused silica substrates with dimensions of 10 mm × 10 mm × 2 mm were used. Through systematic optimization of pulse energy, scanning speed, and inter-focus spacing, Type I waveguide arrays with different channel counts and cladding waveguides with varied track numbers were fabricated in a single longitudinal scan. Free-space end-face coupling at 633 nm was used to characterize the insertion loss, near-field mode profiles, and polarization dependence of the fabricated waveguides. Based on this technique, a 1×9 beam splitter was fabricated by dynamically switching between a ring-shaped hologram for the input cladding waveguide and a rectangular hologram for the output Type I waveguide array.

Results and Discussions

Multi-focus arrays including 2×2, 3×3, 4×4 rectangular matrices and ring-shaped patterns with 8 to 16 foci were generated with high fidelity, as verified by CCD imaging at the Fourier plane. For Type I waveguide arrays, a 2×2 array was fabricated with a total pulse energy of 8.4 μJ and a scanning speed of 2 mm/s. The inter-focus spacing of 9 μm effectively suppressed thermal cross-talk between adjacent channels. All waveguides exhibited approximately circular cross-sections with an average mode-field diameter of ~5 μm. Average propagation losses of 1.1 dB/cm (TE) and 1.0 dB/cm (TM) were achieved. For 3×3 and 4×4 arrays, the total pulse energies were increased to 17.9 μJ and 21.7 μJ, respectively, with a reduced scanning speed of 0.4 mm/s to guarantee sufficient energy deposition at each focal spot. All channels maintained regular matrix arrangement without observable inter-channel distortion. Single-mode guidance was confirmed for both polarizations. The 3×3 array exhibited average losses of 0.4 dB/cm (TE) and 0.5 dB/cm (TM), while the 4×4 array achieved losses as low as 0.1 dB/cm (TE) and 0.2 dB/cm (TM).

Cladding waveguides with 8, 10, 12, 14, and 16 damage tracks were fabricated using a total pulse energy of 21.7 μJ and a scanning speed of 0.4 mm/s. The tighter focal spacing in the ring-shaped arrays induced significantly enhanced cumulative energy deposition through superimposed stress and thermal effects, pushing the local modification beyond the positive refractive index change regime into the negative change region dominated by micro-damage and material rarefaction. All cladding waveguides had a diameter of approximately 32 μm. Single-mode transmission was observed under both TE and TM polarizations for all track numbers. The measured propagation losses ranged from 3.62 to 4.83 dB/cm for TE polarization and from 2.98 to 4.17 dB/cm for TM polarization. Increasing the track number densified the cladding boundary, theoretically enhancing transverse confinement; however, it also introduced additional scattering interfaces, resulting in no monotonic trend in propagation loss as a function of track count.

A 1×9 beam splitter was demonstrated by cascading a 16-track cladding waveguide (core diameter 35 μm) as the input stage with a 3×3 Type I waveguide array as the output splitting stage. Hologram switching was executed without sample repositioning, ensuring precise alignment between the two sections. At 633 nm, total insertion losses of 2.20 dB (TE) and 1.37 dB (TM) were measured.

Coclusions

A SLM-based longitudinal femtosecond-laser multi-focus writing technique was successfully developed for parallel and efficient fabrication of optical waveguides and integrated devices in glass. By active wavefront modulation, programmable multi-focus arrays were generated at the objective focal plane, enabling simultaneous inscription of multiple waveguide tracks in a single longitudinal scan. Type I waveguide arrays scaled from 2×2 to 4×4 and cladding waveguides with tunable track numbers from 8 to 16 were fabricated. Type I waveguide exhibited high cross-sectional circularity, polarization-insensitive guidance, and propagation losses comparable to those fabricated by conventional single-focus serial writing. Cladding waveguides shown a slightly larger TE/TM loss difference, while all cladding waveguides maintain stable single-mode guidance under arbitrary polarization. The cascaded integration of a cladding waveguide input and a Type I waveguide array output was achieved through dynamic hologram switching, realizing a 1×9 polarization-independent beam splitter with low insertion loss and high splitting uniformity at 633 nm. Compared with conventional serial writing, the proposed method theoretically reduces the processing time of an N-track structure to 1/N. Compared with transverse writing approaches, the longitudinal geometry eliminates aberration-induced cross-sectional asymmetry. This technique provides a promising route toward rapid prototyping and scalable manufacturing of high-performance photonic integrated devices for applications in quantum photonics, optical interconnects, and waveguide lasers.

Key words

femtosecond laser direct writing / multi-foci / optical waveguide / glass

引用本文

白雪, 宋杨, 任莹莹. 基于SLM的飞秒激光多焦点纵向直写高效制备玻璃光波导. 光电工程, 2026 , 53 (7) : 260102 -1 . DOI: 10.12086/oee.2026.260102

Xue Bai, Yang Song, Yingying Ren. Efficient fabrication of optical waveguides in glass via slm-based multi-foci femtosecond laser longitudinal writing[J]. Opto-Electronic Engineering, 2026 , 53 (7) : 260102 -1 . DOI: 10.12086/oee.2026.260102

正文

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1　引　言

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近年来，光子集成电路向高密度、低损耗、三维集成方向快速发展，光波导作为核心基础器件，其性能、制备精度与效率直接决定光子器件性能与集成规模。飞秒激光直写技术利用超短脉冲在透明材料内部诱导非线性电离，通过局域折射率改变形成导光通道，具备无需掩模、热影响区小、真三维构型等优势，尤其适用于在玻璃、晶体等衬底中制备埋入式低损耗光波导^[1-4]。根据激光能量密度与材料响应的不同，飞秒激光可在玻璃中诱导出I型正折射率改性波导、II型应力双线波导，以及III型包层波导等多种结构^[5-7]，为有源与无源光子器件的单片集成提供了丰富的设计自由度。

传统横向直写利用聚焦物镜将光束汇聚至样品内部，通过样品相对焦点的三维移动来实现波导加工。该模式中样品移动方向与飞秒激光传输方向垂直，易受球差和像散影响，改性截面往往呈现深度方向拉长的椭圆形畸变，导致波导导光特性出现显著偏振敏感性，甚至只能限制某一特定方向的偏振传输^[8-9]。此外，传统方案多采用单焦点逐点扫描，加工多通道波导阵列与复杂结构时存在周期长、通量低的问题^[10-11]。针对上述问题，研究者们开展了大量的工作。例如，基于狭缝整形的方法和重叠控制多次扫描的方法已被用于调控I型波导的几何形貌、尺寸、模场分布及折射率分布等特性^[12-13]，但加工效率仍然受到明显制约。基于空间光调制器(spatial light modulator，SLM)的光场调控技术已在飞秒激光加工中获得广泛应用^[14-16]。通过优化焦场分布，SLM辅助飞秒激光直写可实现并行多焦点加工，成为优化波导性能、提升加工效率的一种有效策略。基于该方法，Li等实现了对单模I型波导截面圆度的灵活高效调控^[17]。Sakakura等利用SLM多焦点结合横向样品平移，在玻璃中实现了三维1×4 I型分支波导分束器的单次扫描制备^[18]。Pospiech等采用动态相位光栅，通过单次扫描直写了二维及三维Y分束器^[19-20]。然而，这些横向写入方案中，激光传播方向与样品运动方向垂直，难以避免像差引起的波导截面椭圆畸变。在包层光波导方面，Cheng等利用基于SLM的狭缝光束整形技术，将所需扫描次数减少至四次，提高了制备效率^[21-22]。Zhang等利用SLM产生的连续或离散环形焦斑强度分布实现了包层光波导的单次直写制备，大幅提升了加工效率^[23-24]。然而，该工作中采用的横向写入方案需将焦平面相对于扫描方向倾斜，增加了光学设计的复杂度。Long等采用纵向写入方案，利用SLM调制的空心光束制备包层光波导，实现了单次扫描加工并避免了像差引起的非对称性^[25]，该方法采用空心贝塞尔光束，焦场分布灵活性上仍存在一定的局限性。

本工作提出一种基于SLM的飞秒激光多焦点纵向直写策略。利用SLM生成飞秒激光多焦点阵列，采用纵向直写(激光传播方向与样品运动方向重合)，从原理上消除像差引起的截面畸变。通过调控加工参数，可控制备了I型波导阵列与环形包层光波导两类不同机理结构，最高实现了4×4 I型阵列及16轨迹包层波导的并行加工，在保证低损耗的前提下显著提升了规模化制备效率。此外，利用SLM实时切换全息图，将作为输入端的大模场包层光波导与作为输出端的I型波导阵列级联，一步式完成1×9分束器件的集成化构筑，为光子集成器件的快速制备提供了可行的技术方案。

2　实验过程

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2.1　飞秒激光加工光波导

实验搭建的飞秒激光纵向多焦点并行加工系统光路如图1所示。光源为一台掺镱光纤飞秒激光放大器(中心波长1030 nm，脉宽约300 fs，重复频率76 kHz)。输出激光经快门后入射半波片调整偏振方向，使其与液晶指向矢方向平行，以获得最大衍射效率。接着，光束通过由透镜L₁和L₂组成的望远系统进行扩束。经反射镜M₁反射后，光束入射至SLM进行焦场整形。SLM加载根据目标光场经由GSW算法生成的计算全息图，对入射波前施加预设相位延迟；经L₃与L₄组成的4f系统后，调制光场传递至数值孔径为0.4的20倍近红外物镜后瞳，最终在物镜焦点处形成设计的多焦点阵列。实验选用反射式纯相位液晶SLM (PLUTO-2.1，Holoeye)，其像素尺寸为8.0 μm，分辨率为1920 pixel×1080 pixel。纯相位调制可在不损失入射能量的前提下实现波前整形；小像素尺寸与高分辨率有利于复杂全息图的高保真再现，且能够精确控制焦点阵列的间距。4f系统的放大倍率根据SLM像素尺寸与物镜数值孔径的匹配需求计算确定，确保生成的多焦点阵列能够被物镜高效聚焦：物镜后瞳直径约为6 mm，SLM有效区域经扩束后需覆盖物镜后瞳，因此4f系统设计为1:1放大(L₃、L₄焦距均为400 mm)，确保调制光场的高频分量能够被物镜收集，避免信息丢失。

待加工样品为双面光学抛光的熔融石英玻璃，尺寸10 mm×10 mm×2 mm。样品固定于三维电动位移台上，加工过程中位移台带动样品沿激光入射方向(z轴)做纵向运动，实现自下而上写入。加工过程由计算机统一控制飞秒激光脉冲能量、扫描速度、SLM全息图切换、激光快门开断、位移台运动及CCD实时成像。通过大量实验验证，获得了优化的加工参数窗口，实现了样品内部按需可控的折射率改性。

2.2　多焦点阵列的生成

多焦点阵列的目标光场分布采用权重GS算法(GSW)在MATLAB环境中设计。该算法通过对各目标焦点的能量引入权重因子进行迭代反馈修正，能够在有限迭代次数内实现较高的能量均匀性^[26]。初始相位采用[0, 2π]范围内均匀随机分布的随机相位；权重更新系数设置为ε = 0.5；迭代次数固定为10次，未额外设置收敛阈值，在计算效率与均匀性之间取得平衡。每次迭代过程中，根据傅里叶平面幅值与平均幅值之间的偏差对目标光场进行加权反馈修正，逐步提高多焦点阵列的能量均匀性。算法以理想多点光强分布为目标，通过傅里叶域迭代逼近，最终输出对应的相位全息图。以2×2矩形阵列为例，图2(a)展示了目标光场分布，给定相邻焦点间距8 pixel的离散光斑分布，算法生成相位全息图如图2(b)所示。全息图加载至SLM后，在透镜L₃后焦面由CCD采集到的实际光斑阵列见图2(c)。其各焦点的归一化能量依次为0.97、1.00、0.95、0.96 (对应焦点位置为左上，右上，左下，右下)，各焦点能量的最大相对偏差为5%，非目标级次杂散光能量低于主瓣能量的5%，满足并行加工对焦斑质量的要求。相邻焦点在物镜焦平面处的间距实际为9 μm，这一数值与SLM中设定的8 pixel间隔相吻合，表明光学系统对目标光场的保真传输能力。为进一步验证全息图设计的正确性，在GSW算法生成相位全息图后，通过角谱法依次计算光场在SLM、透镜L₃、傅里叶平面、透镜L₄以及焦平面的传播过程，获得焦平面理论光强分布，如图2(c)插图所示。仿真结果表明，重构光场能够准确形成目标2×2阵列，与CCD实验测量结果具有较好的一致性，从理论上验证了全息图设计及4f系统光场重构的有效性。对于后续实验中涉及的不同焦点数量矩形阵列以及环形阵列，均采用相同设计流程生成对应的全息图序列。

2.3　波导性能测试表征

加工完成后，采用自由空间端面耦合系统对波导进行表征。633 nm He-Ne激光经物镜聚焦后垂直耦合至波导输入端面，输出端由另一物镜收集并成像至CCD或光功率计。通过精密六维调整架优化输入/输出物镜与波导端面的相对位置，观测不同偏振态(TE/TM)下的近场模式分布、评估导光特性的偏振依赖性，并测定波导在633 nm波长下的传输损耗，波导损耗计算公式如下：

$ P_{\text{out}}=T(1-R)^2P_{\text{in}}\text{e}^{-\alpha L}, $

(1)

式中：P_in为波导入射端功率；P_out为输出物镜后的出射功率；T为耦合效率；R为菲涅尔反射系数；α为传输损耗系数；L为波导长度。

波导的折射率变化量Δn极大值可以通过测量最大受光角θ_m (即能在波导中传输的光线允许的最大入射角)来进行计算^[27]，假设所研究的光波导为折射率突变型，此时有:

$ \Delta n=\frac{\text{(sin}\theta_{\text{m}})^2}{2n_{\text{s}}}, $

(2)

式中：n_s为衬底折射率，这种方法操作简单，适用范围较广，然而误差相对较大，约为30%左右，因此只能用来估测折射率变化。

3　结果与讨论

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3.1　I型光波导阵列

I型波导依靠激光焦点处材料致密化诱导的正折射率改变导光，其加工窗口对脉冲能量极为敏感：能量过低无法形成稳定折射率差，能量过高则可能诱发微爆裂或折射率降低应力区。对于多焦点并行写入，SLM将总入射能量均匀分配至各子焦点。本实验中，2×2阵列对应的总能量为8.4 μJ，平均单焦点能量约为2.0 μJ。采用2 mm/s的纵向扫描速度，自样品底面起始向上写入2 mm长度。图2(d-f)展示了2×2 I型波导阵列的端面显微图像及不同偏振下的近场模式分布。四条波导轨迹清晰分立，未出现相邻改性区交叠现象，表明9 μm的焦点间距已足以避免串扰。波导平均模场直径约5 μm，与单模光纤模场尺寸匹配良好。测得2×2阵列中各波导的平均传输损耗在TE偏振下为1.1 dB/cm，TM偏振下为1.0 dB/cm，表现出优异的偏振无关导光特性，这得益于纵向写入使得改性区折射率分布在波导横截面内具备高度旋转对称性。

通过改变目标光场设计，计算生成了更大规模I型波导阵列的全息图。图3(a)和图3(e)分别展示了3×3和4×4矩阵多焦点阵列的目标光场分布。实际3×3和4×4焦点阵列的各焦点能量的最大相对偏差分别为10%和9%。 3×3和4×4阵列的加工能量分别为17.9 μJ和21.7 μJ，对应的平均单焦点能量约为1.9 μJ和1.3 μJ。两种阵列结构均采用0.4 mm/s的扫描速度。与2×2阵列相比，3×3和4×4阵列的总写入能量相应提升且速度降低，以保证各焦点处有充足的能量沉积以建立稳定折射率变化，避免因通量不足导致改性区域不连续。

图3(b)和图3(f)分别给出了3×3与4×4 I型波导阵列的端面显微形貌。可以看出，即使在焦点密度显著提高的情况下，各波导芯层仍保持规则的矩阵排布，相邻波导界限清晰。各波导端面形貌存在轻微不均匀，主要由各焦点间的能量微小差异引起，这与SLM相位量化误差、算法残差等因素有关。图3(c, d)和图3(g, h)分别对应3×3和4×4阵列在TE与TM偏振下的近场模式分布图。需要说明的是，阵列部分端口周围观测到少量杂散光，原因在于阵列焦点能量均匀性有所下降，同时阵列横向尺寸较大，边缘波导截面出现轻微畸变，导致部分光场泄漏。尽管如此，所有端口仍保持清晰可辨的单模传输。3×3阵列TE与TM偏振下的单波导平均传输损耗分别为0.4 dB/cm和0.5 dB/cm，4×4阵列则分别为0.1 dB/cm和0.2 dB/cm。损耗数值在较窄范围内波动，且未随阵列规模扩大出现系统性恶化，证实了通过同步调节总能量与扫描速度，可有效维持多焦点并行加工的一致性与稳定性。

3.2　包层光波导

包层光波导通过紧密排布的激光损伤轨迹构成低折射率包层，使光场约束在包层内未辐照的高折射率芯区传输。实验设计了轨迹数量为8、10、12、14、16的五种环形焦点分布。各环形阵列中相邻焦点间距保持均匀，SLM上环形直径均为28 pixels。包层光波导的写入总能量统一设定为21.7 μJ，扫描速度0.4 mm/s。因此，对于8、10、12、14、16焦点阵列，其相应的单焦点能量约为2.6 μJ、2.1 μJ、1.7 μJ、1.5 μJ和1.3 μJ。需要说明的是，与I类波导阵列相比，制备包层光波导所采用的相邻焦点间距更小，加工过程中焦点之间的应力和热累积效应相互影响，使得局部区域的累积能量沉积显著增强，从而越过正折射率改性阈值，进入由微损伤和材料稀疏化主导的负折射率变化区间。

图4(a,b)分别展示了8个环形分布焦点设计及相应的计算全息图。图4(c)为在透镜L₃焦平面处使用CCD采集了目标光场的实际分布图，与设计的焦点分布吻合良好，其各焦点能量的最大相对偏差为8%。图4(d)展示了由8条轨迹围成的包层光波导端面显微镜图像，可以看到经纵向扫描后样品内部刻写出8条独立损伤轨迹，均匀环绕中心区域，构成了清晰完整的低折射率包层边界。该包层结构直径约32 μm，与SLM上28 pixels环形直径相吻合。图4(e, f)为波导传输模式，可见在TE与TM偏振模式下，波导输出端均呈现单模传输，未观察到基底漏光现象。测得TE偏振损耗为4.79 dB/cm，TM偏振损耗为4.41 dB/cm。

为进一步考察轨迹密度对导光性能的影响，固定包层外径不变，逐步将轨迹数增加至10、12、14、16条，相应的设计焦点分布如图5(a1-a4)所示。实际10、12、14和16焦点阵列的各焦点能量的最大相对偏差分别为9%、11%、12%和15%。包层光波导端面如图5(b1-b4)所示，不同焦点数量下均呈现清晰的改性轨迹。随着轨迹数的增加，环向不均匀性有一定程度的提升，主要由焦斑能量均匀性下降、小间距下应力与热累积的环向分布不均共同导致。图5(c1-c4)和图5(d1-d4)为不同偏振下波导传输模式，所有包层波导均实现了任意偏振下稳定的单模传输。对不同波导在TE和TM偏振下传输损耗的测试结果表明，TE偏振下损耗位于3.62~4.83 dB/cm，TM偏振下损耗则维持在2.98~4.17 dB/cm。增加轨迹数使得包层边界更趋于连续，理论上可增强对芯层光场的横向束缚，但同时也引入了更多损伤界面带来的散射损耗，因此，随着波导包层痕迹数量的增加，波导损耗未呈现明显单调变化趋势。

3.3　1×9分束器的集成制备与性能评估

在上述分立波导阵列制备基础上，进一步演示了分束器件的集成化快速制造。分束器设计采用“包层传输-I型阵列分光”的两级级联架构，即使用环形分布的焦点阵列制备作为输入端的包层光波导，用于接收输入并将其扩展为大模场光斑；输出端则无缝衔接I型波导阵列，将入射光束分为多束输出。整个器件的制备仅需在加工程序中切换两次全息图：首先加载环形焦点全息图完成包层输入端刻写，随后立即切换为矩形焦点全息图续写I型波导阵列输出端，期间样品保持原位，确保两级结构的精确对准。

以1×9分束器为例，图6(a)展示了其结构示意图，为使输入端包层结构的模场更好地覆盖输出端，输入端包层结构芯径设计为35 μm，输出端衔接3×3 I型波导阵列(波导间距9 μm)。输入端包层光波导制备对应的目标光场分布模拟图和计算全息图分别见图6(b, c)。图6(d)为输入端目标光场的实际分布图。输出端波导阵列的加工与图3中3×3阵列一致。图6(e, f)分别展示了在633 nm波长下分束器输入端和输出端的显微镜图像。经测量，输入端光波导的包层区域

$ \Delta\rm{\mathit{n}} $

约为−10⁻³，Ⅰ型光波导单条波导

$ \Delta\rm{\mathit{n}} $

约为+10⁻³。图6(g, h)分别为分束器在TE和TM偏振下输出端的模式分布图，证实了该分束器可在任意偏正下实现有效分光。表1显示了TE和TM偏振下各输出端口的归一化分光比，后续可通过优化包层芯径与输出阵列的模场匹配、改进GSW算法以提高多焦点能量均匀性等方法进一步提升分光均匀性。端面耦合测得TE偏振下总插入损耗为2.20 dB，TM偏振下为1.37 dB。该器件首次实现了包层与I型波导的级联集成，验证了该策略在复杂光子器件快速制备中的可行性与任意偏振分光的优势。

4　结　论

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本文发展了一种基于空间光调制器的飞秒激光多焦点纵向直写技术，用于在玻璃内部并行、高效地制备光波导及集成器件。通过对入射激光波前进行主动相位调制，可在物镜焦点处生成可编程的多焦点阵列，从而在单次纵向扫描中同步完成多条轨迹的写入。通过系统优化焦点间距与激光通量，实现了I型波导阵列从2×2到4×4规模的可控制备以及轨迹数目从8至16可调的环形包层光波导加工。所制备波导截面圆度优良，支持任意偏振下的光传输，其中I型波导具有偏振无关特性，传输损耗与常规单焦点直写器件相当。进一步地，利用SLM全息图的原位动态切换，实现了包层光波导与I型波导阵列的级联集成，成功制备出1×9 分束器，器件在任意偏振下均能实现分光功能，充分体现了该方法的灵活性与高效集成能力。

与传统单焦点串行直写相比，本方法将N条轨迹波导的加工时间理论上缩减至1/N；与横向多焦点方案相比，纵向加工消除了像差引起的截面畸变，保证了横截面的高度对称性。总体而言，该方法在波导截面对称性、结构灵活性、器件集成便捷性及加工通量方面均具有显著优势。未来工作中，我们将搭建通信波段测试平台开展实验验证，并围绕全息图优化算法以进一步改善焦斑均匀性、拓展该方法至晶体等各向异性介质等方面开展研究，以推动该技术在集成量子光子学、光互连及波导激光器等领域的实用化进程。

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2026年第53卷第7期

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doi: 10.12086/oee.2026.260102

接收时间：2026-04-28
首发时间：2026-10-22
出版时间：2026-07-25

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收稿日期：2026-04-28
修回日期：2026-06-16
录用日期：2026-06-18

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山东师范大学物理与光电学院，山东省光场调控物理及应用重点实验室，山东济南 250358

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任莹莹，ryywly@sdnu.edu.cn

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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