Development of a high average power picosecond fiber amplifier for biomedical applications

激光手术代表着一个快速增长的巨大且有利可图的市场。许多激光现在被广泛用于各种医疗程序，即普通外科、眼科和美容。一般来说，为了**获得高水分组织的有效切割，例如用于医疗程序，需要使用与水强烈相互作用的激光**源。此外，为了避免对侧支组织的热损伤，激光通常在短脉冲状态下运行。为了满足激光手术的要求，光物质相互作用公司(LMI)开发了一种激光系统，该系统可以产生2.9微米**波长的高能皮秒脉冲，接近水的绝对最大吸收。这种激光系统已经**证明了它的效率，可以满足眼科手术中最苛刻的应用。然而，LMI开发的激光系统**基于低效的固态频率下转换架构**，这导致产生脉冲光的整体电光效率**接近2.9微米。此外，这种笨重的激光系统基于非线性频率转换**，因此需要水冷却以所需的能量和功率水平运行，这是其在医疗市场上商业化的主要**障碍。这项Engage Plus拨款提案代表着与LMI在2018年通过最近**完成的旨在改善光纤激光系统性能的Engage拨款**所做合作的直接延续。在这个为期6个月的**项目中，我们成功地展示并在一份高影响力的激光科学杂志上发表了**概念光纤放大器，它可以产生2.9微米的高能脉冲，最大平均功率为2.5W，**非常适合眼科激光手术。目前提案的目标是将平均**输出功率和脉冲能量分别提高到10W级和500microJ级，以支持要求最苛刻的医疗激光程序。

Laser surgery represents a huge and profitable market growing at a rapid rate. Many lasers are now commonly**used for various medical procedures namely in general surgery, ophthalmology and aesthetics. Generally, to**obtain an efficient cutting of high-water content tissues, such as for medical procedures, the use of a laser**source that strongly interacts with water is required. Moreover, to avoid thermal damage to collateral tissues,**lasers are generally operated in short pulsed regime. To meet the requirements of laser surgery, Light-Matter**Interaction Inc. (LMI) has developed a laser system that produces high-energy picosecond pulses at a**wavelength of 2.9 microns, near the absolute maximum absorption of water. This laser system has**demonstrated its efficiency to meet the most demanding applications in ophthalmologic procedures. However,**the laser system developed by LMI is based on an inefficient solid-state architecture of frequency down**conversion, which results in a quite low overall electrical to optical efficiency for the generation of pulsed light**near 2.9 microns. Moreover, this cumbersome laser system is based on nonlinear frequency conversion**therefore requiring water-cooling to operate at the required energy and power level, which are major**impediment to its commercialization in the medical market. This Engage Plus grant proposal represents the**direct continuation of a recent collaborating effort with LMI made in 2018 through an Engage grant recently**concluded with the scope of improving the performances of a fiber-based laser system. Over this 6 months**project, we successfully demonstrated and published in a high-impact journal in laser science a proof of**concept fiber amplifier producing high-energy pulses near 2.9 microns at a maximum average power of 2.5W,**perfectly adapted for laser surgery in ophthalmology. The goal of the current proposal is to increase the average**output power and pulse energy to the 10W-level and 500microJ-level respectively to support the most**demanding medical laser procedures.