Stimulated emission and absorption of radiation and amplification using stimulated emission

Introduction Previous discussions (see Section 10.4) suggested that stimulated emission can be used to generate optical gain, that is, to amplify radiation. The reader certainly has experience in the amplification of electronic signal. For example, radio receivers capture faint radio waves and turn them into a signal that is powerful enough to drive large speakers. This electronic amplification increases the amplitude of the signal while faithfully preserving its acoustic frequencies and modulation characteristics. Similarly, optical amplification is expected to increase the amplitude of an optical signal while preserving its frequency, its modulation characteristics, and its coherence. The latter requirement is of particular significance for optical radiation, where the coherence of naturally occurring radiation rarely exceeds one micrometer. Lasers are the primary source for coherent radiation. They depend on stimulated emission for amplification and for the generation of coherent radiation (the word laser is the acronym of Light Amplification by Stimulated Emission of Radiation). For amplification, an atomic system that is part of the laser medium must be prepared with a sufficiently large number of particles in the excited state. (The term atomic system is used here to describe all microscopic systems including molecules and free electrons.) Radiation passing through that excited medium encounters multiple events of stimulated emission, each event contributing one photon that is added coherently to the propagating beam. When the number of events of stimulated emission exceed all losses by absorption or scattering, the incident radiation is amplified.Introduction Previous discussions (see Section 10.4) suggested that stimulated emission can be used to generate optical gain, that is, to amplify radiation. The reader certainly has experience in the amplification of electronic signal. For example, radio receivers capture faint radio waves and turn them into a signal that is powerful enough to drive large speakers. This electronic amplification increases the amplitude of the signal while faithfully preserving its acoustic frequencies and modulation characteristics. Similarly, optical amplification is expected to increase the amplitude of an optical signal while preserving its frequency, its modulation characteristics, and its coherence. The latter requirement is of particular significance for optical radiation, where the coherence of naturally occurring radiation rarely exceeds one micrometer. Lasers are the primary source for coherent radiation. They depend on stimulated emission for amplification and for the generation of coherent radiation (the word laser is the acronym of Light Amplification by Stimulated Emission of Radiation). For amplification, an atomic system that is part of the laser medium must be prepared with a sufficiently large number of particles in the excited state. (The term atomic system is used here to describe all microscopic systems including molecules and free electrons.) Radiation passing through that excited medium encounters multiple events of stimulated emission, each event contributing one photon that is added coherently to the propagating beam. When the number of events of stimulated emission exceed all losses by absorption or scattering, the incident radiation is amplified.

Cambridge University Press eBooksJul 13, 19960 citations

Stimulated Emission from Donor Transitions in Silicon

Sergei G. Pavlov, Roman Kh. Zhukavin, Ekaterina E. Orlova +5 more

The observation of far-infrared stimulated emission from shallow donor transitions in silicon is reported. Lasing with a wavelength of $59\ensuremath{\mu}\mathrm{m}$ due to the neutral donor intracenter ${2p}_{0}\ensuremath{\rightarrow}1s(E)$ transition in Si:P pumped by ${\mathrm{CO}}_{2}$ laser radiation is obtained. Populations of ${D}^{0}$ and ${D}^{\ensuremath{-}}$ center states and the balance of the radiation absorption and amplification are theoretically analyzed.The observation of far-infrared stimulated emission from shallow donor transitions in silicon is reported. Lasing with a wavelength of $59\ensuremath{\mu}\mathrm{m}$ due to the neutral donor intracenter ${2p}_{0}\ensuremath{\rightarrow}1s(E)$ transition in Si:P pumped by ${\mathrm{CO}}_{2}$ laser radiation is obtained. Populations of ${D}^{0}$ and ${D}^{\ensuremath{-}}$ center states and the balance of the radiation absorption and amplification are theoretically analyzed.

Physical Review LettersMay 29, 2000158 citations

{\mathrm{CO}}_{2}

laser radiation is obtained. Populations of

{D}^{0}

and ${D}^{\ensuremath{-}}$ center states and the balance of the radiation absorption and amplification are theoretically analyzed.