/mlrumtntoción Revi,~ta Mezicana de Fú.ica 37 No. 4 {199¡} 665-.670 N 2 MOPA system with coaxial laser amplifier Víctor J. Pinto., Vicente Aboites Laboraton'o de láseres, Centro de Investigacione,'l en Gp/ica, A.C. Apartado poslal 948, :17000 León, Guanajuato, México and J. de la Rosa Escuela Superior de Ingeniería Mecánica Elictriro Instituto Politécnico Nacional, 07738 Mézico, D.F., México (Recibido el 7 de enero de 1991; act"ptado el 27 de mayo de 1991) Abstract. A coaxial N 2 laser excited .•••. ith a Polloni circuit ha.s b<'Cn used as an amplifier in a MOPA configllration using a conv('ntional Blumlein N 2 laser as oscillator. A high amplification efficiency .•••. as obtained. Synchronization was achieved using a lIniqlle spark gap and an oplica] deJay line. The experimental r('suits pres('nted are discussed and compar('d with lhe results reporled hy othC'rworhrs, PACS: 42.60.-v: 42.60.By: 42.SS.Em L Introduction Nitrogen Jaser systems working in oscillator-amplifier configurations have beco de- veloped to achieve the best characteristics of N 2 lasers in a unique systcm. It is well known that the transient nature of the population invcrsion in N 2 has limitcd the oulput power obtainable with these lasers [9J and only by Ilsing ~lOr" systems the power has becn incrcased. Besides lhe improvements in the output power oblainahlc there are impro\'ements in the quality of the heam by lhe use of amplifier config- urations; spatial and sp£"Ctral characteristics of the lwam can he controlled ver)' effectivcly by ¡nsertjon of speetral filtcrs or spatial filtering schernes, Low di\'ergence and correded apatial profilcs are regularly obtained with tb('se systems. 1'0 extract high power CroInan N 2 rnediurn, it is necessary to ha\'c high density excitation during a period which is short compared with the I¡fetime oCthe excited laser le\'el « 40 nsee). Foe the MOPAsystem to operate efficiently the oscillator pulse must always reach the amplifier at the time oC maximum populalion inversion. This means that the amplifier excitation pul!'e must be synchronized w¡lh the arrival of the aptical pulse by sorne meaos, Delay lines can be aplical or e1cclricaL In lhe first case, the optical pulse CroIn the oscillalor must travel a ccrtain distancc guidcd by mirrors or aptical components to acrive to the amplificr at the time oC optimum population inversion. Such lines are practical when the <lelay is Icss than 10 ns. • Now at: Physics Department, Essex Universit)" F.ngla.ndC04 JSQ.