Inverse-Designed Ultracompact Pulse Shapers for Femtosecond-Scale Photonic Computing

Abstract

Ultrafast optical pulse shaping is a key technology for emerging areas such as ultrahigh-bandwidth optical communications, precision spectroscopy, and ultrafast optical computing. Existing approaches rely on discrete optical components or centimeter-scale waveguides, which impose fundamental limits on size, bandwidth, and integration, hindering the development of next-generation on-chip photonic systems requiring compact, broadband, and highly integrable pulse processing. Here, we present an ultracompact ultrafast pulse shaper, realized through inverse design on a silicon-on-insulator platform, experimentally demonstrated with a footprint of only 5 × 5 μm2. Precise nanoscale control of the refractive index allows a single device to perform complex temporal envelope transformations, including Gaussian pulse differentiation, double-pulse splitting, and triangular or square pulse generation, on a 100 fs time scale, with processing bandwidths of tens of terahertz. The first-order differentiator further enables image edge detection, illustrating parallel signal processing with nanosecond latency and terahertz throughput. This approach combines subwavelength compactness with femtosecond-level temporal resolution, approximately 100 times faster than electronic GHz processors, offering a versatile platform for on-chip ultrafast optical computing and real-time signal processing.