[9a-PA5-1~3] 4.2 Photonics Devices, Photonic Integrated Circuit and Silicon Photonics

English Presentation

[9a-PA5-1] Bandgap Engineering to Control Amplification at Telecom Wavelengths in Photonic Time Crystals

〇Anupreet Ghosh¹, Snehashis Sadhukhan^1,2, Bishnu P. Pal¹, Somnath Ghosh¹ (1.Mahindra Univ., 2.IIT Jodhpur)

Keywords:

Phtotnic time crystals,Time varying media,Temporal photonic crystal

Photonic time crystals (PTCs) are temporal periodic media that exhibit momentum bandgaps and unique wave amplification mechanisms arising from energy exchange with the external modulation. In this work, we investigate bandgap engineering in a binary PTC to achieve controllable amplification at the telecom wavelength of 1550 nm. The Floquet band structure is analyzed using the transfer-matrix formalism, revealing momentum bandgaps where the quasi-frequency becomes complex, leading to exponential field growth. By varying the modulation period and temporal width ratio, the position and width of the momentum bandgaps can be systematically tuned. The resulting bandgap shifts enable alignment of the amplification bands with the target telecom wavelength. Amplified transmittance calculations demonstrate strong gain within the momentum-gap regions, with maximum amplification occurring when the propagating-wave momentum overlaps with the engineered bandgap centre. These results establish temporal bandgap engineering as an effective approach for controlling amplification in photonic time crystals and provide a promising route toward compact ultrafast photonic amplifiers and future time-varying optical communication devices.