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

激光手术代表着一个巨大且利润丰厚的市场，正在快速增长。许多激光现在普遍用于各种医疗程序，即普通外科，眼科和美学。一般来说，为了**获得高含水量组织的有效切割，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，为了避免对侧枝组织的热损伤，**激光器通常在短脉冲状态下工作。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，可以产生波长为2.9微米的高能皮秒脉冲，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，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下变频架构，这导致在2.9微米附近产生脉冲光的整体电光效率非常低。此外，这种笨重的激光系统基于非线性变频**，因此需要水冷却才能在所需的能量和功率水平上运行，这是其在医疗市场商业化的主要障碍**。这项Engage Plus拨款提案代表了最近与LMI在2018年进行的合作努力的直接延续，该合作是通过最近的一项Engage拨款**完成的，其范围是提高基于光纤的激光系统的性能。在这个为期6个月的项目中，我们成功地展示并在激光科学的高影响力期刊上发表了一个概念验证光纤放大器，该放大器产生近2.9微米的高能脉冲，最大平均功率为2.5W，**完全适合眼科激光手术。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，以支持最苛刻的医疗激光手术。

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.