Frosz Michael H, Moselund Peter M, Rasmussen Per D, Thomsen Carsten L, Bang Ole
DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Ørsteds Plads 343, DK-2800 Kgs. Lyngby, Denmark.
Opt Express. 2008 Dec 8;16(25):21076-86. doi: 10.1364/oe.16.021076.
Supercontinuum light sources spanning into the ultraviolet- visible wavelength region are highly useful for applications such as fluorescence microscopy. A method of shifting the supercontinuum spectrum into this wavelength region has recently become well understood. The method relies on designing the group-velocity profile of the nonlinear fiber in which the supercontinuum is generated, so that red-shifted solitons are group-velocity matched to dispersive waves in the desired ultraviolet-visible wavelength region. The group-velocity profile of a photonic crystal fiber (PCF) can be engineered through the structure of the PCF, but this mostly modifies the group-velocity in the long-wavelength part of the spectrum. In this work, we first consider how the group-velocity profile can be engineered more directly in the short-wavelength part of the spectrum through alternative choices of the glass material from which the PCF is made. We then make simulations of supercontinuum generation in PCFs made of alternative glass materials. It is found that it is possible to increase the blue-shift of the generated supercontinuum by about 20 nm through a careful choice of glass composition, provided that the alternative glass composition does not have a significantly higher loss than silica in the near-infrared.
覆盖紫外-可见波长区域的超连续谱光源在诸如荧光显微镜等应用中非常有用。一种将超连续谱转移到该波长区域的方法最近已被充分理解。该方法依赖于设计产生超连续谱的非线性光纤的群速度分布，以使红移孤子在所需的紫外-可见波长区域与色散波实现群速度匹配。光子晶体光纤（PCF）的群速度分布可以通过PCF的结构来设计，但这主要改变的是光谱长波长部分的群速度。在这项工作中，我们首先考虑如何通过选择制造PCF的玻璃材料的替代方案，更直接地在光谱的短波长部分设计群速度分布。然后，我们对由替代玻璃材料制成的PCF中的超连续谱产生进行了模拟。结果发现，通过仔细选择玻璃成分，只要替代玻璃成分在近红外区域的损耗不比二氧化硅高很多，就有可能将产生的超连续谱的蓝移增加约20纳米。
