Time Stretch with Continuous-Wave Lasers

Abstract: A single-shot measurement technique for ultrafast phenomena with high throughput enables the capture of rare events within a short time scale, facilitating the exploration of rare ultrafast processes. Photonic time stretch stands out as a highly effective method for both detecting rapid events and achieving remarkable speed in imaging and ranging applications. The current time stretch method relies on costly passive mode-locked lasers with continuous and fixed spectra to capture fast transients and dilate their time scale using dispersion. This hinders the broad application of time stretch technology and presents synchronization challenges with ultrafast events for measurement. Here we report the first implementation of time stretch using continuous wave (CW) diode lasers with discrete and tunable spectra that are common in WDM optical communication. This approach offers the potential for more cost-effective and compact time stretch systems and simplifies laser synchronization with the input signal. Two different embodiments in the United States and Japan demonstrate the technique's operation and limitations, and potential applications to time stretch imaging and angular light scattering.