Programmable Optical Filter in Thin-Film Lithium Niobate with Simultaneous Tunability of Extinction Ratio and Wavelength

Abstract

On-chip optical filters are of key importance to many modern applications such as optical interconnections and wavelength division multiplexing systems. In all these scenarios, simultaneous tunability of the extinction ratio and working wavelength is particularly essential for the optical filters to construct the optical networks but remains a scientific challenge. Here, we demonstrate a novel optical filter on the thin-film lithium niobate platform, where both the extinction ratio and working wavelength can be simultaneously and independently tuned by adjusting two loaded electro-optic modulators. The device demonstrates the tunability of the extinction ratio from 0 to over 25 dB at a fixed working wavelength. On the other hand, the filter, with a footprint of 1.2 mm × 0.65 mm, also shows over 100 pm linewidth with a resonant wavelength tunability of 12.5 pm/V at the critical coupling condition.

High-Speed Electro-Optic Modulators Based on Thin-Film Lithium Niobate

“…There are several challenges associated with the physical dry etching of LN. First, considering the low selectivity of etched materials and available photoresists, hydrogen silsesquioxane (HSQ) [6,[19][20][21][22][23][24], Zeon electron-beam positive-tone resist (ZEP) [25], CSAR [26], SU8 [27], as well as hard marks including Cr and Si are commonly used. The second challenge is nonvertical sidewalls with an angle ranging from 40 • to 80 • , which results from LN redeposition during dry etching.…”

LiNbO3 Thin Films through a Sol–Gel/Spin-Coating Approach Using a Novel Heterobimetallic Lithium–Niobium Precursor

“…Therefore, a more elaborate growth process is required for the development of a stoichiometric single crystal of LN than the well-known Czochralski process used for congruent LN single crystal growth [ 9 , 10 ]. The potential for developing LiNbO 3 thin films is of particular interest for integrated and miniaturized devices such as optical filters, optical waveguides or modulators, and reduced control voltage [ 6 , 11 , 12 ]. In fact, epitaxial thin films of LN have found applications in various devices so far, including optical switches [ 13 ], photonic crystals [ 14 ], solid-state batteries [ 15 ], surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices [ 16 , 17 , 18 ], and quantum memories [ 19 ].…”

LiNbO3-based memristors for neuromorphic computing applications: a review

“…The ferroelectric property makes lithium niobate have significant applications in various fields, including optics, acoustics, and information processing (Edon et al, 2009;Wu et al, 2020;Chen et al, 2021b;Lin et al, 2022). For instance, LiNbO 3 is applied in polarization management due to high fidelity polarization generation with an extinction ratio that can exceed 41.9 dB and a high polarization scrambling rate of over 64 Mrad s −1 (Lin et al, 2022;Hou et al, 2023).…”