Feedback-induced first-order Freedericksz transition in a nematic film

Abstract
It is shown that optical-electrical feedback can transform the Freedericksz transition in a nematic film from second order to first order. The criteria that indicate whether the Freedericksz transition is first or second order are obtained. The hysteresis accompanying the first-order transition versus the feedback intensity is discussed. The feedback-induced first-order Freedericksz transition has been observed experimentally. The experimental results are in good agreement with the theoretical analysis.