On-chip amplification-free fCEO detection and broadband SCG in parabolically width-modulated TFLN waveguides

TL;DR

This paper presents a novel on-chip, amplification-free method for carrier-envelope offset detection using parabolically width-modulated TFLN waveguides, achieving broadband supercontinuum generation and high SNR for self-referenced frequency combs.

Contribution

It introduces the first fully amplification-free, on-chip fCEO detection technique with broadband SCG in engineered TFLN waveguides, setting new performance benchmarks.

Findings

Achieved over two octaves of broadband supercontinuum spanning 600-2400 nm.

Demonstrated the highest SNR for amplification-free fCEO detection to date.

Enabled robust self-referencing without optical or electronic amplifiers.

Abstract

We demonstrate amplification-free carrier-envelope offset (fCEO) detection in parabolically width-modulated z-cut thin-film lithium niobate (TFLN) waveguide that simultaneously engineers dispersion and enhances nonlinear interactions. With 116 fs pulses at 1560 nm, the device generates more than two octaves broadband SCG spanning 600 to beyond 2400 nm, enabling spectral overlap between dispersive waves and second-harmonic generation near 780 nm for robust f-2f self-referencing. Most notably, we achieve the first fully amplification-free, on-chip fCEO detection without optical or electronic amplifiers, obtaining 34 dB SNR at 100 kHz RBW and 57 dB at 100 Hz RBW, the highest reported to date under such conditions. These results establish a new benchmark for scalable, power-efficient, self-referenced frequency combs and quantum-enabled photonic systems.