Experimental detection of bistable inverted states in a traveling-wave maser

M. I. Kliot-Dashinskii

I. R. Senitzky

J. E. Geusic, H. E. D. Scovil

The subject of masers is introduced by giving an historical account of events which led to the amplification of microwave radiation by an inverted population in a system of weakly interacting ammonia molecules. The introduction also outlines the development of masers up to the present. Sections 2 and 3 are concerned with maser fundamentals. Methods for obtaining inverted populations are discussed in § 2. Section 3 is devoted to the theory of maser gain and noise. This is followed by a discussion of microwave solid state masers. Microwave maser materials and the development of unidirectional travelling wave maser amplifiers are emphasized. Optical masers are treated in § 5. In this section the theory of optical amplifiers and oscillators is outlined. Also included in the theoretical discussion is a rather lengthy consideration of pump power requirements in optically pumped masers. This is followed by a survey of solid state, semiconductor and gaseous optical masers. The review ends with some comments on the extension of masers to new wavelength regions.

D. N. Makovetskii, Alexander A. Lavrinovich, N. T. Cherpak

The nonlinear dynamics in a paramagnetic maser amplifier is investigated experimentally and theoretically under conditions such that the active medium exerts a sufficiently strong feedback influence on the pump field to induce population inversion of the spin levels. Branching of the inversion ratio due to the onset of bistability in the nonlinear microwave cavity of the pump at a frequency of 150 GHz is observed experimentally. Conditions are determined for the possible excitation of new nonlinear resonances when the spin system is inverted by a standing-wave field, and the stability of the resulting stationary nonequilibrium states of the paramagnet is analyzed.

Anthony Mazzocco, Michael Avilés, Jim Andrews +2 more

Wouter D’Oosterlinck, Geert I. Morthier, Roel Baets +1 more

We investigate the bistable response of a traveling-wave semiconductor optical amplifier (SOA) connected bidirectionally to a distributed feedback (DFB) laser diode. By contrast to dispersive DFB amplifiers, bistability is possible for a broad wavelength range of the injected optical signal. A theoretical analysis clarifies the origin of the phenomenon and the conditions under which it occurs. Numerical simulations and experimental results confirm the theoretical analysis. Experimentally obtained step heights up to 25 dB and widths of the bistability domain of 1-4 dB have been found