TADPOLE measures ultrashort pulses with zeptojoule energies

April 1, 1996
Investigators at the Combustion Research Facility of Sandia National Laboratories (Livermore, CA) have developed a method to measure femtosecond laser pulses with average energies of hundreds of zeptojoules (10-21 J). Termed temporal analysis by dispersing a pair of light E-fields (TADPOLE), the technique is 1 billion times more sensitive than the laboratory`s frequency-resolved optical-gating (FROG) method, from which TADPOLE is derived.

TADPOLE measures ultrashort pulses with zeptojoule energies

Investigators at the Combustion Research Facility of Sandia National Laboratories (Livermore, CA) have developed a method to measure femtosecond laser pulses with average energies of hundreds of zeptojoules (10-21 J). Termed temporal analysis by dispersing a pair of light E-fields (TADPOLE), the technique is 1 billion times more sensitive than the laboratory`s frequency-resolved optical-gating (FROG) method, from which TADPOLE is derived.

In a FROG device, the laser pulse is first split to create two "replicas" of itself. Mirrors direct these pulses to arrive at a nonlinear crystal so they overla¥in time (see Laser Focus World, Nov. 1994, p. 9). The spectra produced by the overlapping pulses change with differences in the time delay and provide the intensity and phase versus time of the initial pulse. Because a nonlinear optical crystal is required, FROG sensitivity is limited to measuring pulses having picojoule energies or more. Many researchers, however, need to measure pulses that are much weaker. The key to TADPOLE, explains Sandia`s Rick Trebino, is that "you never have a weak pulse by itself. The nonlinear processes that occur in short-pulse lasers require that they emit strong pulses, which eventually make the weak ones." Developed in conjunction with Ian Walmsley at the University of Rochester (NY), TADPOLE combines a FROG measurement of the strong pulse--used as a reference--with spectral interferometry, which yields the phase difference between the reference and the unknown pulse being measured. The technique has measured pulses with average energies as low as 42 zeptojoules.

Sponsored Recommendations

March 31, 2025
Enhance your remote sensing capabilities with Chroma's precision-engineered optical filters, designed for applications such as environmental monitoring, geospatial mapping, and...
March 31, 2025
Designed for compatibility with a wide range of systems, Chroma's UV filters are engineered to feature high transmission, superior out-of-band blocking, steep edge transitions...
March 31, 2025
Discover strategies to balance component performance and system design, reducing development time and costs while maximizing efficiency.
March 31, 2025
Explore the essential role of optical filters in enhancing Raman spectroscopy measurements including the various filter types and their applications in improving signal-to-noise...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!