arXiv subjects

Pierre Didier

Publications and source records attributed to Pierre Didier.

3 recordsLinked to original sources

arXiv2026

Integrated tunable mid-infrared electro-optic frequency comb generator based on nonlinear conversion

Mid-infrared frequency combs enable highly selective and sensitive molecular spectroscopy by leveraging the strong vibrational transitions in this spectral region. Among these, there is a particular need for compact, tunable sources with electronic control over comb parameters for integrated sensing platforms. In this work, we demonstrate a mid-infrared electro-optic frequency comb source based on nonlinear frequency conversion in thin film lithium niobate. The system combines a near-infrared pump, amplitude-modulated using an integrated Mach-Zehnder modulator for lock-in detection, with a telecom-band electro-optic comb generated via a double-pass phase modulation scheme. Mid-infrared comb generation is achieved through difference frequency generation in a periodically poled waveguide. By tuning the telecom seed laser and the chip temperature, we obtain mid-infrared combs with a bandwidth of approximately 6 nm and center wavelength tunability of over 200 nm. The comb free spectral range is directly controlled via the applied radio-frequency modulation. Operation across multiple integrated photonic circuits reaching wavelengths up to 3.7 $\mu$m is demonstrated. Furthermore, dual-tone EO comb generation in the mid-infrared is realized. To our knowledge, this is the first integrated mid-infrared electro-optic comb source offering independent electronic control of both center wavelength and comb spacing.

physics.optics↗

arXiv2026

Integrated electro-optic attention nonlinearities for transformers

Transformers have emerged as the dominant neural-network architecture, achieving state-of-the-art performance in language processing and computer vision. At the core of these models lies the attention mechanism, which requires a nonlinear, non-negative mapping using the Softmax function. However, although Softmax operations account for less than 1% of the total operation count, they can disproportionately bottleneck overall inference latency. Here, we use thin-film lithium niobate (TFLN) Mach-Zehnder modulators (MZMs) as analog nonlinear computational elements to drastically reduce the latency of nonlinear computations. We implement electro-optic alternatives to digital Softmax and Sigmoid, and evaluate their performance in Vision Transformers and Large Language Models. Our system maintains highly competitive accuracy, even under aggressive 4-bit input-output quantization of the analog units. We further characterize system noise at encoding speeds up to 10 GBaud and assess model robustness under various noise conditions. Our findings suggest that TFLN modulators can serve as nonlinear function units within hybrid co-packaged hardware, enabling high-speed and energy-efficient nonlinear computation.

cs.LG↗

arXiv2025

Integrated thin film lithium niobate mid-infrared modulator

The mid-infrared spectral range holds great promise for applications such as molecular spectroscopy and telecommunications. Many key molecules exhibit strong absorption features in this range, and free-space optical communication benefits from reduced atmospheric attenuation and low transmission losses in specific wavelength bands spanning from 3 to 14 $\mu m$. Recent progress in MIR photonics has been fuelled by the rapid development of efficient light sources and detectors. However, further advancement is hindered by the lack of low-loss, high-performance integrated photonic platforms and modulators. Lithium niobate on sapphire is a promising candidate, operating across a broad spectral range from 0.4 $\mu m$ to 4.5 $\mu m$. We demonstrate a broadband, high-speed lithium niobate on sapphire Mach-Zehnder electro-optic modulator operating from 3.95 to 4.3 $\mu m$. The device achieves a 3 dB bandwidth exceeding 20 GHz, an extinction ratio of 34 dB, and a half-wave voltage of 22 V$\cdot$cm, delivering optical output power at the half-milliwatt level. These properties are leveraged to demonstrate data transmission at 10 Gbit/s. The modulator is also used to generate a frequency comb with a width of 80 GHz. Furthermore, we demonstrate full $\pi$-phase modulation in the MIR, representing a key milestone for integrated MIR photonics. These results establish a pathway toward high-speed, energy-efficient MIR photonic systems for applications in telecommunications, sensing, and quantum technologies.

physics.optics↗