Lasing without inversion
Lasing without inversion (LWI),Marvin J. Weber. {{cite book | title=Handbook of Lasers | publisher=CRC Press | year=2019 | isbn=978-1-4200-5017-2 | url=https://books.google.com/books?id=ZS_3DwAAQBAJ&pg=PA1151|page=1151}} or lasing without population inversion, is a technique used for light amplification by stimulated emission without the requirement of population inversion.{{cite journal|title=Lasers without inversion: Interference of lifetime-broadened resonances|year=1989|last1=Harris|first1=S. E.|journal=Physical Review Letters|volume=62|pages=1033–1036|issue=9|doi= 10.1103/PhysRevLett.62.1033 |bibcode = 1989PhRvL..62.1033H|pmid=10040407}} A laser working under this scheme exploits the quantum interference between the probability amplitudes of atomic transitions in order to eliminate absorption without disturbing the stimulated emission.{{cite journal |title=Lasing without inversion|year=2000|last1=Mompart|first1=J.|last2=Corbalán|first2=R.|journal=J. Opt. B|volume=2|issue=3|doi= 10.1088/1464-4266/2/3/201|bibcode = 2000JOptB...2R...7M|pages=R7–R24|s2cid=121209763 |url=http://pdfs.semanticscholar.org/a2dd/fa99e29dbb021fb0c8fd92c5af7f15353d60.pdf|archive-url=https://web.archive.org/web/20200101024559/http://pdfs.semanticscholar.org/a2dd/fa99e29dbb021fb0c8fd92c5af7f15353d60.pdf|url-status=dead|archive-date=2020-01-01}} This phenomenon is also the essence of electromagnetically induced transparency.Scully, M., & Zubairy, M. (1997). Chapter 7. In Quantum optics (p. 220). Cambridge: Cambridge University Press.
The basic LWI concept was first predicted by Ali Javan in 1956.Scully, M., & Zubairy, M. (1997). Chapter 7. In Quantum optics (p. 245). Cambridge: Cambridge University Press.A. Javan, Phys. Rev. 107, 1579 (1956) The first demonstration of LWI was carried out by Marlan Scully in an experiment in rubidium and sodium at Texas A&M University, and then at NIST in Boulder.Javan, A. (2000). "On knowing Marlan". In Ode to a quantum physicist: A festschrift in honor of Marlan O. Scully. Elsevier.