Thin-film lithium-niobate electro-optic platform for spectrally tailored dual-comb spectroscopy

Abstract

Laser frequency comb generators on photonic chips open up the exciting prospect of integrated dual-comb microspectrometers. Amongst all nanophotonic platforms, the technology of low-loss thin-film lithium-niobate-on-insulator shows distinguishing features, such as the possibility to combine various optoelectronic and nonlinear optical functionalities that harness second- and third-order nonlinearities, and thus promises the fabrication of a fully on-chip instrument. Here, a critical step towards such achievement is demonstrated with an electro-optic microring-based dual-comb interferometer. Spectra centered at 191.5 THz and spanning 1.6 THz (53 cm−1) at a resolution of 10 GHz (0.33 cm−1) are obtained in a single measurement without requiring frequency scanning or moving parts. The frequency agility of the system enables spectrally-tailored multiplexed sensing, which allows for interrogation of non-adjacent spectral regions, here separated by 6.6 THz (220 cm−1), without compromising the signal-to-noise ratio. Our studies show that electro-optic-based nanophotonic technology holds much promise for new strategies of molecular sensing over broad spectral bandwidths.

A power-efficient integrated lithium niobate electro-optic comb generator

“…The recent technological advances in the LN-on-insulator (LNOI) photonic platform have inspired a renaissance for EO combs to be achieved in chip-scale systems that are more efficient, more compact and lower cost [24][25][26][27][28][29][30] . In the LNOI platform, a sub-micron-thick LN thin film is bonded on top of SiO2 dielectric substrate, resulting in much better light confinement, and substantially improved EO modulation efficiencies [24][25][26][27][28][29][30][31][32][33][34][35][36] . As a result, breakthroughs have been made on LNOI-based on-chip EO comb generators in aspects of spectral breadth, light conversion efficiency and comb line flatness [24][25][26][27][28][29][30] .…”

“…In the LNOI platform, a sub-micron-thick LN thin film is bonded on top of SiO2 dielectric substrate, resulting in much better light confinement, and substantially improved EO modulation efficiencies [24][25][26][27][28][29][30][31][32][33][34][35][36] . As a result, breakthroughs have been made on LNOI-based on-chip EO comb generators in aspects of spectral breadth, light conversion efficiency and comb line flatness [24][25][26][27][28][29][30] . For example, EO combs generated using a single LN resonator can cover the entire telecom L band with over 900 lines 24 , and light conversion efficiency can be further improved to 30% using a tworesonator system 27 .…”

Fabrication of Low Loss Lithium Niobate Rib Waveguides Through Photoresist Reflow

“…ITHIUM niobate (LN) is a nonlinear optical material widely used for applications in optical frequency conversion, optical modulation, and quantum information science. The thin film lithium niobate on insulator (LNOI) platform has seen extensive use over the past decade to demonstrate compact on-chip devices such as second harmonic generators, optical parametric oscillators, electro-optical modulators, entangled photon sources, and frequency combs [1]- [12]. Systems utilizing LN benefit from the wide transparency range of the material which spans from ultraviolet to mid infrared [13].…”

A power-efficient integrated lithium niobate electro-optic comb generator

“…The recent technological advances in the LN-on-insulator (LNOI) photonic platform have inspired a renaissance for EO combs to be achieved in chip-scale systems that are more efficient, more compact and lower cost [24][25][26][27][28][29][30] . In the LNOI platform, a sub-micron-thick LN thin film is bonded on top of a SiO 2 dielectric substrate, resulting in much better light confinement, and substantially improved EO modulation efficiencies [24][25][26][27][28][29][30][31][32][33][34][35][36] . As a result, breakthroughs have been made on LNOI-based on-chip EO comb generators in aspects of spectral breadth, light conversion efficiency and comb line flatness [24][25][26][27][28][29][30] .…”