This paper presents a closed-form analysis of the synchronization phenomenon of the quantum cascade laser(QCL).The analysis has been made with considering higher order nonlinearity of the modal gain of the QCL.The frequency response characteristics of the synchronized QCL along with the stability of the locked state,the effect of nonlinearity on the lockband of the QCL and the amplitude limiting action of the locked QCL have been calculated.The analysis demonstrates the effect of higher order no...