Time stretch with continuous-wave lasers

Abstract

Ultrafast single-shot measurement techniques with high throughput are needed for capturing rare events that occur over short time scales. Such instruments unveil non-repetitive dynamics in complex systems and enable new types of spectrometers, cameras, light scattering, and lidar systems. Photonic time stretch stands out as the most effective method for such applications. However, practical uses have been challenged by the reliance of current time stretch instruments on costly supercontinuum lasers and their fixed spectrum. The challenge is further exacerbated by such a laser’s rigid self-pulsating characteristic, which offers no ability to control the pulse timing. The latter hinders the synchronization of the optical source with the incoming signal—a crucial requirement for the detection of single-shot events. Here, we report the first demonstration of time stretch using electro-optically modulated continuous wave lasers. We do this using diode lasers and modulators commonly used in wavelength-division-multiplexing optical communication systems. This approach offers more cost-effective and compact time stretch instruments and sensors and enables the synchronization of the laser source with the incoming signal. Limitations of this new approach are also discussed, and applications in time stretch microscopy and light scattering are explored.