Characteristics of the radiation emitted by a bismuth silicate (BSO) photorefractive ring laser

A theoretical analysis is made of the characteristics of the radiation emitted by a bismuth silicate photorefractive ring laser operating under conditions of monodirectional or bidirectional emission. The dependences of the intensities and frequencies of the output waves on the detuning of the pump frequency from the natural frequency of the resonator ω_p–ω_N are calculated. It is shown that the range of the frequency detuning ω_p–ω_N where lasing is possible depends strongly on the length of the photorefractive crystal. A study is reported of the frequency characteristic of a rotating photorefractive ring laser (representing the dependence of the frequencies of counterpropagating waves on the angular velocity). The scaling coefficient K of photorefractive ring lasers is shown to be 6–7 orders of magnitude less than the corresponding coefficient of gas ring lasers, i.e., the difference between the frequencies of the counterpropagating waves and a rotating photorefractive ring laser is practically independent of the angular velocity.