The 395-FIR contains two far-infrared (FIR) laser cavities that are identical and present within a single 5 bar invar stabilized frame.
The device is custom designed for applications that require two FIR outputs, such as plasma diagnostics, with a single frequency offset from the other by up to a few MHz.
A single high power CO2 laser – the PL6 laser - is used to pump FIR cavities of the 395. This ensures accurate stability of the Intermediate Frequency (IF). The two identical pump beams are generated by a 50/50 beam splitter.
FIR laser frequencies originate from rotational transitions in an excited vibrational state of a polar gas molecule at low pressure.
The optically pumped FIR laser relies on the elective absorption of tunable IR radiation in order to form a population inversion between rotational states, generating laser action. A small number of molecules are selected to provide discrete frequencies across the whole FIR spectrum from 40 µm upwards. Tables of FIR lines can be provided on request.