**KOÇ UNIVERSITY PHYSICS SEMINAR**

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**Speaker : **Hamed Ghaemi-Dizicheh, Koç University

**Title : **Nonlinear spectral singularities and laser output intensity

**Date : **December 14, 2018 **(Friday)**

**Time :** 10:30 A.M.

**Cookie&Tea :** SCI 103 10:15 A.M.

**Place :** **SCI 103**

**Web : **http://physics-seminars.ku.edu.tr

**Abstract : ** The nonlinear spectral singularity arising from a Kerr nonlinearity is explored in [Phys. Rev. A 87, 063838 (2013)]. This reference studies the effect of nonlinearity in Lasing condition and shows that Kerr nonlinearity with spectral singularity for a normally incident wave provides an explanation of lasing at gain coefficient “g”. Lasing occurs when it exceeds threshold gain “g_0”. For oblique waves, Ref. [Phys. Rev. A 91, 043804 (2015)] looks at the behavior of threshold gain coefficient “g_0” which is given by the condition that there is a linear spectral singularity. We investigated imposing the condition of the existence of a nonlinear spectral singularity in the TE\TM modes of a mirrorless slab of gain materials and studied the angle-dependence of intensity.

**Short Bio : ** Ghaemi-Dizicheh obtained his MS degree from Isfahan University of Technology, Iran and he is a Ph.D. candidate at Koç University since 2013. His dissertation advisor is Prof. Ali Mostafazadeh, and he investigates nonlinear spectral singularity in optical models.