Fibre lasers have a large share of the laser material processing market but are typically limited to aerospace and defence applications in the sensing market segment. That is set to change within the next decade as emerging applications of fibre laser technologies include automotive LiDAR, multi-species gas sensing and structural health monitoring.
In a standard automotive LiDAR system, laser diodes emit coherent infra-red (IR) radiation that reflects from nearby objects and is detected by sensors in the vehicle. Once the reflected signal is processed by software, the control system directs the vehicle to avoid obstacles. Conventional products offered by LiDAR manufacturers such as Velodyne (USA) utilise numerous laser diodes that emit radiation at a wavelength of 905 nm. Recently, fiber laser LiDAR has emerged as a novel alternative with several advantages. Fiber-based LiDAR products function at a longer wavelength of 1,550nm. This eye-safe wavelength enables the LiDAR system to operate at higher powers and offer long-range sensing for autonomous vehicles; superior resolution and full functionality with fewer lasers are additional advantages. As the technology is based on an optical fiber, the absence of mechanical components provides excellent system stability and long product lifetime.
Luminar Technologies (USA) are a fast-growing start-up commercialising fibre laser LiDAR, and Volvo made a large investment in the company in June 2018. Toyota were the first automotive manufacturer to form a partnership with Luminar and began testing an autonomous vehicle with fibre laser LiDAR in 2017. Compared to many products in the automotive LiDAR market today, Luminar’s product offers 10x the range and 50x the resolution, which significantly improves the available reaction time for safer autonomous driving. The company also developed a cost-effective, high dynamic range infra-red sensor for their LiDAR system, which is suitable for high-volume manufacturing. Fibre laser manufacturers optimising products for autonomous vehicles and gaining attention from the automotive industry include Lumibird (France) and O-Net (China).
An analysis of fibre laser sensing technologies and markets is available in a report titled Fiber Lasers 2018-2028: Technologies, Opportunities, Markets & Forecasts, which was recently published by the British technology consulting company IDTechEx. The report provides company profiles and product overviews of 22 fibre laser suppliers, which includes all major suppliers based in Europe, USA and Asia in addition to examples of specialist suppliers developing products optimised for sensing. IDTechEx forecast the global fibre laser market to reach a size of $8.9 billion in 2028 with strong growth in the LiDAR & Sensing segment.
Supercontinuum fibre laser sources, such as those developed by the French Aerospace Lab ONERA, are also emerging as an important sensing technology. Unlike conventional monochromatic lasers, supercontinuum fibre lasers provide a broadband spectrum while maintaining the high brightness and high beam quality characteristics. The high spatial coherence of fibre lasers make them ideal for remote multi-species gas sensing, where the 1-5 μm infra-red spectral region contains absorption peaks of numerous pollutants and volatile organic compounds. Applications of this technology include environmental pollution monitoring and detection of chemical contaminants in industrial accidents or terrorist attacks. The IDTechEx report also reviews commercial suppliers of supercontinuum fibre laser products.
Fibre lasers are also useful for automated structural health monitoring and are an alternative to piezoelectric sensors. Organizations such as the US Naval Research Laboratory have reported highly sensitive fibre laser systems designed to detect fatigue before a critical level in naval vessels such as submarines. The technique involves resolving acoustic signatures from crack formation and other damage. Future applications of this technology include monitoring the critical parts prone to fatigue and failure in infrastructure and civilian aircraft.