Experimental setup for temporal synthesis and characterization.

To obtain a multioctave phase coherent spectrum, Harris and co-workers drive the fundamental vibrational transition in deuterium using two lasers. This produces a set of equidistant, mutually coherent sidebands that are separated from each other by the difference of the frequencies of the driving lasers and extend from 2.94 microns in the infrared to 195 nanometres in the ultraviolet.

A prism is then used to disperse the sidebands and a subset of seven sidebands extending from 1.56 microns to 410 nanometres is then sent through a liquid crystal light modulator. The sidebands are recombined and focused into a target xenon cell.

A solar-blind photomultiplier (PMT) measures UV radiation that is generated in the xenon cell. The intensity of the generated UV wavelengths depends on the relative phases and amplitudes of the incident optical signal. The 1.56 micron sideband is not seen by the camera (Phys. Rev. Lett. 94 033904).