SELF-OSCILLATIONS OF AN OPTICALLY BISTABLE ELEMENT WITH VERY BROAD HYSTERESIS IN A HYBRID RING CAVITY

We investigate thermally induced optical nonlinearity of a glass doped with semiconductor quantum dots. With the feedback of a Fabry-Perot resonator this glass shows dispersive optical bistability. The reflected light signal is coupled to a hybrid ring cavity with a round trip time much longer than that of the Fabry-Perot resonator and even longer than the thermal relaxation time of the glass. The self -oscillations occurring for certain input parameters are regular and the appearance of different modes as a function of the light intensity coupled to the resonator is observed. Due to the broad hysteresis and the high inclination of both branches of the bistable loop we observe large numbers of ascending and descending steps in the output intensity, i.e., long oscillation periods. A simple model of adiabatic simulations by an iterated map shows that the mode structure follows a Farey-tree construction.