通过空心光子晶体光纤改善飞秒激光脉冲传输以用于时间聚焦双光子内镜检查。

Improving femtosecond laser pulse delivery through a hollow core photonic crystal fiber for temporally focused two-photon endomicroscopy.

作者信息

Choi Heejin, So Peter T C

机构信息

Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

1] Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA [2] Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA [3] BioSym, Singapore-MIT Alliance for Research and Technology, Singapore 138602, Singapore [4] Laser Biomedical Research Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

出版信息

Sci Rep. 2014 Oct 15;4:6626. doi: 10.1038/srep06626.

DOI:10.1038/srep06626

PMID:25316120

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4894416/

Abstract

In this paper, we present a strategy to improve delivery of femtosecond laser pulses from a regenerative amplifier through a hollow core photonic crystal fiber for temporally focused wide-field two-photon endomicroscopy. For endomicroscope application, wide-field two-photon excitation has the advantage of requiring no scanning in the distal end. However, wide-field two-photon excitation requires peak power that is 10(4)-10(5) times higher than the point scanning approach corresponding to femtosecond pulses with energy on the order of 1-10 μJ at the specimen plane. The transmission of these high energy pulses through a single mode fiber into the microendoscope is a significant challenge. Two approaches were pursued to partially overcome this limitation. First, a single high energy pulse is split into a train of pulses with energy below the fiber damage threshold better utilizing the available laser energy. Second, stretching the pulse width in time by introducing negative dispersion was shown to have the dual benefit of reducing fiber damage probability and compensating for the positive group velocity dispersion induced by the fiber. With these strategy applied, 11 fold increase in the two photon excitation signal has been demonstrated.

摘要

在本文中，我们提出了一种策略，用于改善飞秒激光脉冲从再生放大器通过空心光子晶体光纤的传输，以实现时间聚焦的宽场双光子内窥成像。对于内窥成像应用，宽场双光子激发的优势在于远端无需扫描。然而，宽场双光子激发所需的峰值功率比点扫描方法高10⁴ - 10⁵倍，这对应于在样品平面上能量约为1 - 10 μJ的飞秒脉冲。将这些高能量脉冲通过单模光纤传输到微型内窥镜中是一项重大挑战。我们采用了两种方法来部分克服这一限制。首先，将单个高能量脉冲分裂成一系列能量低于光纤损伤阈值的脉冲，从而更好地利用可用激光能量。其次，通过引入负色散来拉伸脉冲宽度，已证明具有降低光纤损伤概率和补偿光纤引起的正色散这两个双重益处。应用这些策略后，双光子激发信号已实现11倍的增强。