Broadband wavelength-swept Cr⁴⁺:YAG crystal fiber laser

Professor Sheng-Lung Huang

Graduate Institute of Photonics and Optoelectronics, National Taiwan University

台湾大学光电所 黄升龙教授

We present a broadband wavelength-swept laser using a 16-μm-core-diameter Cr⁴⁺:YAG crystal fiber as the gain medium. The laser-diode-pumped crystal fiber laser has a threshold of only 102 mW due to the low propagation loss and high heat dissipation efficiency. The laser achieves a sweeping wavelength range of 134 nm, centered around 1425 nm, with a scanning speed of 163k nm/s. Notably, the cross-polarization-coupled excited state absorption of the signal wavelength constrained the long-wavelength lasing limit. This laser has the potential for swept source optical coherence tomography applications, providing an axial resolution of 11.4 μm.

Reference:

Y. H. Li, Y. W. Lee, and S. L. Huang, "Broadband wavelength-swept Cr⁴⁺:YAG crystal fiber laser," Optics Express 31(20), pp. 32772–32782, 2023.

True-H&E Rapid Fresh Pathology Assisted with Mesoscale Nonlinear Optical Gigascope

Professor Chi-Kuang Sun

Graduate Institute of Photonics and Optoelectronics, National Taiwan University

台湾大学光电所 孙启光教授

Hematoxylin and Eosin (H&E)-based frozen section (FS) pathology is presently the global standard for intraoperative tumor assessment (ITA). Preparation of frozen section is labor intensive, which might consume up-to 30 minutes, and is susceptible to freezing artifacts. An FS-alternative technique is thus necessary, which is sectioning-free, artifact-free, fast, accurate, and reliably deployable without machine learning and/or additional interpretation training.

Our team develop a training-free true-H&E Rapid Fresh digital-Pathology (the-RFP) technique which is 4 times faster than the conventional preparation of frozen sections. The-RFP is assisted by a mesoscale Nonlinear Optical Gigascope (mNLOG) platform with a streamlined rapid artifact-compensated 2D large-field mosaic-stitching (rac2D-LMS) approach. A sub-6-minute True-H&E Rapid whole-mount-Soft-Tissue Staining (the-RSTS) protocol is introduced for soft/frangible fresh brain specimens. The mNLOG platform utilizes third harmonic generation (THG) and two-photon excitation fluorescence (TPEF) signals from H and E dyes, respectively, to yield the-RFP images.

Our team demonstrate the-RFP technique on fresh excised human brain specimens. The-RFP enables optically-sectioned high-resolution 2D scanning and digital display of a 1 cm² area in <120 seconds with 3.6 Gigapixels at a sustained effective throughput of >700 M bits/sec, with zero post-acquisition data/image processing. Training-free blind tests considering 50 normal and tumor-specific brain specimens obtained from 8 participants reveal 100% match to the respective formalin-fixed paraffin-embedded (FFPE)-biopsy outcomes.

In conclusion, we provide a digital ITA solution: the-RFP, which is potentially a fast and reliable alternative to FS-pathology. With H&E-compatibility, the-RFP eliminates color- and morphology-specific additional interpretation training for a pathologist, and the-RFP-assessed specimen can reliably undergo FFPE-biopsy confirmation.

论文题目：硅基萧特基热载子宽带光侦测器之研究

姓名：苏子钧   指导教授：林清富教授

摘要

随着物联网技术的发展，我们的生活变得越来越便利。光子感应器作为关键技术，能够将入射光转换为电信号，因此受到关注。因应微型智能设备的发展需求，新一代光探测器需要与硅基集成电路兼容，以提供高级计算和分析功能。本研究主要探讨铬/硅萧特基二极管传感器，透过铬和硅基板之间的萧特基接面，微弱的中红外光响应被初步观察。透过界面工程解决萧特基界面常见的费米能阶钉札效应后，能障高度降至0.49 eV和0.47 eV，接近理论值0.45 eV，噪声从0.43 nA降至0.09 nA，响应提升45%达到234 μA/W，并在4、5和6 μm光下分别有5.56、2.11和1.75 μA/W的响应。此外，在电子或光子注入后，热载子与晶格碰撞，导致能量交换，扩展了可测量光谱范围，超越硅能隙限制。为覆盖整个中红外光范围，我们开发并应用了一种周期排列的倒金字塔结构，诱导的强烈局部表面电浆共振效应提高了响应，接近mA/W水平。即使在5.3 μm波长下，热载子机制使组件响应达0.237 mA/W。本研究结果显示，热载子组件对中红外光子检测的响应速度有所提高，呈现出具有高于2.1 MHz的3 dB带宽的光学频率响应，极具发展潜力。最后，本研究中也透过热载子组件实现了对多种分子气体的检测，预计这些成果将为未来气体浓度传感器和光谱分析仪器提供技术基础。 图一、具超宽带光谱响应的热载子萧特基光传感器的光入射以及其上的倒立式金字塔结构 图二、LSPR在金属材料中引起的热载子动态变化，包含热载子的能量再分配和空间扩散效应

— 资料提供：影像显示科技知识平台 (DTKP, Display Technology Knowledge Platform) —

— 整理：林晃岩教授、黄茂恺 —

千万亿位（Petabit）光学储存

光学数据储存长期以来一直被提议作为硬盘（HDD）和半导体闪存的替代方案。然而，其瓶颈在于储存容量受限于光学绕射的极限，这限制了写入的光学数据位的物理大小及其间距。

现在，Zhao及其同事在《自然》期刊上报导了一种新的光学基板和超高分辨率光学数据编码译码方法，使得一般DVD大小的基板具备了约1.6千万亿位（Petabit）的储存容量（M. Zhao et al. Nature 626, 772–778; 2024）。

关键技术是一种新的光学数据储存媒介，即掺杂染料的光阻（photoresist），该光阻显示出来自发色团的聚集诱导发光（aggregation-induced emission, AIE）。数据写入是透过聚焦两束激光到记录区域来实现的（见图一a左侧）。第一束是515奈米的飞秒激光，触发局部光聚合，而第二束是639奈米的甜甜圈形连续波CW光束，在这之后就结束整个过程，将记录限制在sub-diffraction的光点。类似借鉴于STED显微镜，作者展示了最小约54奈米的写入光点和70奈米的横向轨道间距（见图一a右侧）。其中光学读取依赖记录光点的AIE，这些光点可以用共轭焦或STED显微镜来成像。讯息的写入还可以多达100层、且垂直间距为1微米的三维编码来记录（见图二）。

这是一项令人印象深刻的成就，正如来自上海科技大学的该研究通讯作者Gu Min教授在《自然光子学》上所说：「在三维几何中消除绕射极限障碍具有科学意义，这为其它三维设备在感测、生物医学成像和有机电子学中的奈米级激光写入铺平了道路。」在数据储存方面，极其密集的三维写入使一般DVD 大小的储存容量达到1.6千万亿位（Petabit），相当于目前最先进HDD容量的24倍。这一发展使得建立放置在房间内的千千万亿位级（exabit-level）数据中心成为可能，而不需要体育场空间大小的HDD。

尽管在讯息密度方面的展示确实令人瞩目，但在写入速度方面仍有改进的空间，目前写入速度受限于所需的100毫秒曝光时间和激光功率，现在需要峰值强度为2.14GW/cm²的脉冲激光。Gu教授建议：「要改善这些条件，可以在高效材料中使用高度平行的写入和读取。上转换（upconversion）奈米颗粒是其中一个可能的候选材料。」