The {sup 2}P{sub 1/2} {yields} {sup 2}P{sub 3/2} laser transition in atomic iodine and the problem of search for signals from extraterrestrial intelligence

• Published in: Quantum electronics (Woodbury, N.Y.) Vol. 37; no. 7
• Main Authors: Kutaev, Yu F, Mankevich, S K, Nosach, O Yu, Orlov, E P
• Format: Journal Article
• Language: English
• Published: United States 31.07.2007
• Subjects: ABSORPTION; ASTROPHYSICS; BEAMS; BOSONS; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COHERENT SCATTERING; DIFFRACTION; DISTANCE; EARTH ATMOSPHERE; ELEMENTARY PARTICLES; ELEMENTS; EMISSION; GAS LASERS; HALOGENS; IODINE; IODINE LASERS; LASERS; MASSLESS PARTICLES; NONMETALS; OPTICAL SYSTEMS; PHOTON BEAMS; PHOTON EMISSION; PHOTONS; PHYSICS; PULSES; SCATTERING; SENSITIVITY; SIGNALS; SORPTION; STARS; TELESCOPES; WAVELENGTHS
• DOI: 10.1070/QE2007V037N07ABEH013534
• ISSN: 1063-7818

It is proposed to search for signals from extraterrestrial intelligence (ETI) at a wavelength of 1.315 {mu}m of the laser {sup 2}P{sub 1/2} {yields} {sup 2}P{sub 3/2} transition in the atomic iodine, which can be used for this purpose as the natural frequency reference. The search at this wavelength is promising because active quantum filters (AQFs) with the quantum sensitivity limit have been developed for this wavelength, which are capable of receiving laser signals, consisting of only a few photons, against the background of emission from a star under study. In addition, high-power iodine lasers emitting diffraction-limited radiation at 1.315 {mu}m have been created, which highly developed ETI also can have. If a ETI sends in our direction a diffraction-limited 10-ns, 1-kJ laser pulse with the beam diameter of 10 m, a receiver with an AQF mounted on a ten-meter extra-atmospheric optical telescope can detect this signal at a distance of up to 300 light years, irrespective of the ETI position on the celestial sphere. The realisation of the projects for manufacturing optical telescopes of diameter 30 m will increase the research range up to 2700 light years. A weak absorption of the 1.315-{mu}m radiation in the Earth atmosphere (the signal is attenuated by less than 20%) allows the search for ETI signals by using ground telescopes equipped with adaptive optical systems. (laser applications and other topics in quantum electronics)