| |
 |
UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:52 |
 |
|
|
|
Conference: Bucharest University Faculty of Physics 2009 Meeting
Section: Optics, Spectroscopy, Plasma and Lasers
Title:
High Peak-Power Passively Q-switched Nd:YAG/Cr4+:YAG Laser for Engine Ignition
Authors:
Gabriela SALAMU, Oana SANDU, Nicolaie PAVEL, and Traian DASCALU
Affiliation:
National Institute for Laser, Plasma and Radiation Physics,
Laboratory of Solid-State Quantum Electronics, Bucharest R-077125, Romania
E-mail
gabriela.salamu@inflpr.ro
Keywords:
Nd-doped laser, diode-pumped, passive Q-switch, Cr4+:YAG
Abstract:
Passive Q-switching technique can simplify a laser setup, and improve its efficiency, reliability and compactness. Recent research has shown that laser-induced ignition in internal combustion engines presents many advantages over a conventional spark-ignition system. The most suitable laser scheme for engine ignition seems to be a Nd:YAG laser passively Q-switched by Cr4+:YAG saturable absorber crystal. In this work, we report our approach and recent results toward realization of a Nd:YAG/Cr4+:YAG that could be used for engine ignition.
The laser employs a 0.7-at.% Nd:YAG that was end pumped with pulsed diode lasers. Various Cr4+:YAG crystals with initial transmission, Ti between 0.30 and 0.60, and different resonators were tested in order to obtain pulses with high energy and short duration. Q-switch laser pulses with 1.05-mJ energy and duration of 4.2 ns, which corresponds to a pulse peak power of 250 kW, were obtained at room temperature of 25oC from a 60-mm long plane-plane resonator equipped with a Cr4+:YAG crystal of Ti= 0.30 and an output mirror with transmission T= 0.40. Modeling of the output performances were performed using a rate equations model, and good agreement with the experiments was obtained.
A laser used for ignition has to withstand hard-working conditions. A tough condition is imposed by temperature that could change on a wide range, typically from -40oC to 150oC. Therefore, in a new set of experiments the Nd:YAG/Cr4+:YAG laser was placed in an oven, and Q-switch pulse characteristics were investigated function of temperatures up to 150oC. Data shows that increase of temperature has minor effect on pulse energy and duration, but higher energies of the pump pulse are necessary at elevated temperatures in order to maintain Q-switch operation. Main reasons for this behavior were the variation with temperature of Nd:YAG spectroscopic properties, and changes of laser beam inside the resonator configuration.
|
|
|
|