Fiber laser sensing trends: LiDAR, gas detection & structural health
Aug 17, 2018
Fiber 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 fiber 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) utilize 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 1550 nm. 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.
Fiber laser manufacturers optimizing products for autonomous vehicles and gaining attention from the automotive industry include Lumibird (France) and O-Net (China). In January 2018, Keopsys Quantel (prior to Lumibird rebranding) told IDTechEx about their strategy for scaling up the production and reducing the unit price of 1550 nm fiber lasers for automotive LiDAR applications. In July 2018, Lumibird reported +42% growth in revenue for their LiDAR business division, with first-half revenues increasing from $4.9 million in 2017 to $7.0 million in 2018. New production lines were installed in March 2018 and fiber lasers were successfully demonstrated in autonomous vehicles, resulting in growing interest from the transport sector.
Meanwhile, Luminar (USA) are a fast-growing start-up who are also commercializing 1550 nm LiDAR technology. The company employ several fiber laser engineers in their R&D team and are advertising to recruit more in 2018. A typical light source design proposed by Luminar in their patents is a laser diode (semiconductor device) combined with single or multi-stage fiber amplifiers (erbium doped) to produce high-power 1550 nm infrared radiation. 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 1550 nm 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 infrared sensor for their LiDAR system, which is suitable for high-volume manufacturing.
An analysis of fiber laser sensing technologies and markets is available in a report titled Fiber Lasers 2018-2028: Technologies, Opportunities, Markets & Forecasts, which was recently published by IDTechEx Research. The report provides company profiles and product overviews of 22 fiber laser suppliers, which includes all major suppliers based in Europe, USA and Asia in addition to examples of specialist suppliers developing products optimized for sensing. IDTechEx forecast the global fiber laser market to reach a size of $8.9 billion in 2028 with strong growth in the LiDAR & Sensing segment.
Preview of the global fiber laser market forecast based on original research by IDTechEx. Source: IDTechEx
Supercontinuum fiber 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 fiber lasers provide a broadband spectrum while maintaining the high brightness and high beam quality characteristics. The high spatial coherence of fiber 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 titled Fiber Lasers 2018-2028: Technologies, Opportunities, Markets & Forecasts also reviews commercial suppliers of supercontinuum fiber laser products.
Atmospheric absorption of gas species in the infra-red spectral region of the ONERA supercontinuum fiber laser source. HF absorption is divided by a factor of 10 for ease of visibility. Source: ONERA
Fiber 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 fiber 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.
Fiber laser sensors for structural health monitoring can be employed in buildings, bridges, aircraft and naval vessels. Source: Ramboll
Top image: Single frame of a street environment captured with Luminar 1550 nm LiDAR. Source: Luminar Technologies