tech details

Electrically Distributed Optically Pumped Laser Spark Plug and Ignition System

Opportunity

Research is active on the patented technology, titled "Electrically Distributed Optically Pumped Laser Spark Plug and Ignition System." This technology is available for licensing and/or further collaborative research from the U.S. Department of Energy’s National Energy Technology Laboratory.


Overview

When used as an ignition source for reciprocating engines, laser spark ignition has been shown to improve efficiency and reduce harmful emissions. Optical distribution of pump pulses to a laser spark plug is a technically sound approach; however, in practice it has been difficult to achieve. Traditional laser diode bars used for pumping solid state lasers are temperature-sensitive and relatively difficult to focus, due to their vast difference in axial divergence. Laser diode bar systems have typically been sealed in large, bulky independent containers that include exotic optical systems used to couple the light of many diode bars into an optical fiber. This type of system must be optically distributed, and the process can be extremely difficult without high precision and expensive mechanics, which are prone to mechanical failure.

The recent development of laser diode bars with Bragg gratings and microlenses has greatly reduced temperature dependency of the output wavelength and improves array divergence and focusability, allowing the high-power diode pump source to be located at the laser spark plug. Electrical distribution is now a viable competitor in today’s marketplace because laser optics, coatings, materials, and pump sources are now small enough and have sufficient power and low cost. This invention describes an electrical distribution system that delivers high-current pulses to optical pumping devices producing optical pumping power that can be collected and focused to coaxially pumped, solid state, passively Q-switched lasers. The lasers, in turn, produce high-peak power output, which can be focused into a combustion chamber to ignite a lean, high pressure air/fuel mixture.


Significance

  • Laser distribution system reduces high-peak power optical requirements for laser ignition and distribution systems, allowing use of optical fibers for delivering lower energy pumping pulses to a laser amplifier or laser oscillator (laser spark plug)
  • When incorporated with a laser spark plug ignition system, enables natural gas-fired engines to be operated at higher compression ratios and leaner fuel/air ratios, resulting in lower NOx emissions
  • Distribution system is designed to be easily adaptable to existing ignition systems


Applications

  • Natural gas-fueled reciprocating engines used for pumping and power generation
  • Potentially applicable to other ignition needs, including gas turbine engines
  • Technology may be applied to laser-induced breakdown spectroscopy and other diagnostic sensor devices


Related Patents

U.S. Patent No. 8,934,511 issued January 13, 2015, titled "Laser Interlock System."

Inventors: Dustin McIntyre and Steven Woodruff


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