We describe the use of a coupling electromagnetic field to provide a general method of producing inversion-free laser systems. The interference between dressed states produces a zero in absorption while allowing gains of the order of that of the uncoupled system.
© 1989 Optical Society of America
A. Imamoğlu and S. E. Harris, "Lasers without inversion: interference of dressed lifetime-broadened states," Opt. Lett. 14, 1344-1346 (1989)