Carrier-envelope phase stabilization with a petahertz optical chip

Source data and processing for the paper titled "Carrier-envelope phase stabilization with a petahertz optical chip".Abstract of the paper: Stabilization of the carrier-envelope phase (CEP) in trains of laser pulses is essential for generating optical frequency combs for ultraprecise metrology and for studying ultrafast, lightwave-controlled laser-matter interactions. Conventional CEP detection is based on nonlinear interferometry, which infers the phase indirectly from a beat-note averaged over many pulses, consumes the sampled light, and requires bulky, wavelength-specific optics preventing integration. In contrast, lightwave-driven currents provide direct and single-shot conversion of the optical waveform to electrical signal, but it has been so far employed only for passive CEP detection and mapping. Here, we extend the use of lightwave-driven currents beyond passive CEP sensing to active CEP control. A solid-state, micrometer-sized petahertz (PHz) optical chip converts the CEP of the incident pulses into a feedback voltage signal, which is employed for interferometry-free waveform stabilization. We induced lightwave-driven currents by mid-infrared pulses for the first time, and we successfully used this approach to CEP-stabilize a 2.3-μm Cr:ZnS oscillator delivering nanojoule pulses at 25 MHz repetition rate. We measured a residual phase jitter of 150 mrad in the laser output. The simple and transmissive chip-scale architecture is not restricted to a specific spectral range and leaves the full beam available for experiments. Our work establishes a direct electrical route towards integrated sources of waveform-stable few-cycle pulses for ultrafast science and PHz electronics.