講演情報
[7p-N204-3]Coincidence of Two EP2s in The Parameter Space of a Gain-Loss Assisted Dual-Core Photonic Crystal Fiber
〇(M2)Shamba Ghosh1, Arpan Roy2, Bishnu P. Pal3, Somnath Ghosh3 (1.IIT Jodhpur, 2.Calcutta Univ., 3.Mahindra Univ.)
キーワード：
Non-Hermitian system、fiber sensor
We propose a gain-loss-assisted dual-core photonic crystal fiber (PCF) that supports multiple second-order exceptional points (EP2s) through carefully engineered mode interactions. The structure is optimized to support six guided modes, enabling strong non-Hermitian coupling between selected mode pairs. By varying the gain coefficient under a fixed loss-to-gain ratio, three distinct EPs are observed between three distinct mode pairs. These EPs are identified via coalescence of the real parts and bifurcation of the imaginary parts of the complex effective indices. Remarkably, two independent EPs are found to coexist at the same point in the 2D parameter space, a novel phenomenon not previously reported. Selective parametric encirclement of each EP results in topological mode switching, confirming their branch point behavior. This work introduces a compact, fiber-integrated platform for tunable, multi-mode EP-based photonic control with applications in ultra-sensitive sensing.