Lichtimpulse

Lichtimpulse, literally light impulses, describes extremely short bursts of electromagnetic radiation used in physics and photonics. These pulses typically last from femtoseconds to picoseconds and can reach high peak powers. They span visible to infrared wavelengths and are central to ultrafast optics, time-resolved spectroscopy, and high-speed signaling.

Generation and sources: Most common are mode-locked lasers that emit a train of ultrashort pulses. Techniques such as chirped pulse amplification (CPA) enable handling high energies without damaging the gain medium. Nonlinear optics and frequency conversion extend the spectral range. On-chip approaches use fast modulators and nonlinear materials to produce short optical bursts.

Properties and measurement: Key characteristics include pulse duration, spectral bandwidth, peak power, repetition rate, and phase stability. Shorter duration implies broader spectra (time-bandwidth product). Pulse shapes can be tailored by pulse shaping. Characterization methods include autocorrelation, frequency-resolved optical gating (FROG), and SPIDER measurements.

Applications: Lichtimpulse enable time-resolved studies of fast processes in chemistry, biology, and condensed matter. They underpin pump-probe experiments, femtosecond spectroscopy, and ultrafast microscopy. In communications and sensing, ultrashort pulses support high data rates and ranging techniques such as LIDAR, while research on pulsed sources advances nonlinear optics and laser machining.

Terminology: The term arises from German, with "Licht" for light and "Impuls" for impulse. In English-language literature, the more general terms "ultrashort optical pulse" or "light pulse" are common. The concept covers both laboratory experiments and practical light-source technologies, continuing to evolve with pulse shaping, stabilization, and integrated photonics.