Apparatus and method for generation of high harmonics from silicon

Extracting information from fast-evolving events requires a probe signal that is shorter in duration than the time of the event.  Lasers may be used for optical probes, but they are generally limited to femtosecond timescales.  Thus, tunable generation of optical probes with a sub-femtosecond timescale is of interest.  Attosecond pulses are mentioned.  Further, accomplishing this with a technically relevant material such as silicon is of interest.  

Generally, converting a Near InfraRed (NIR) or Medium InfraRed (MIR) optical pulse to higher frequencies (e.g. UV) i.e. impart higher energy to photons, is energy intensive.  Here, a coherent UV pulse is created using a  harmonic response in silicon.  A driving field is applied to an interaction zone of silicon.  In one example, the driving field is a laser pulse.  Interaction of the driving  field with the silicon produces higher order harmonic pulses of the original driving field.  A control field is applied to the silicon using one or more terminals, such that the control field is applied to the interaction zone.  Examples of external and internal contacts to the silicon are provided.  The control field is a harmonic of the driving field’s frequency, where it tunes the output harmonic pulse, allowing control of spectral, temporal and spatial properties of the harmonic beam.