Tunable infrared source employing Raman mixing

摘要

A tunable source of infrared radiation is obtained by irradiating an assemblage of Raman active gaseous atoms or molecules with a high intensity pumping beam of coherent radiation at a pump frequency omega p to stimulate the generation of Stokes wave energy at a Stokes frequency omega s and to stimulate the Raman resonant mode at the Raman mode frequency omega R within the irradiated assemblage where the pump frequency omega p minus the Stokes frequency omega s is equal to the Raman mode frequency omega R. The stimulated assemblage is irradiated with a tunable source of coherent radiation at a frequency omega i to generate the output infrared radiation of the frequency omega 0 which is related to the Raman mode frequency omega R and the input wave omega i by the relation omega 0= omega i+/- omega R. In one embodiment the interaction between the pump wave energy omega p and the tunable input wave energy omega i is collinear and the ratio of the phase velocity mismatch factor DELTA k to the electric field exponential gain coefficient T is within the range of 0.1 to 5. In another embodiment the pump wave energy omega p and the tunable input wave energy omega i have velocity vectors kp and ki which cross at an angle to each other to compensate for phase velocity mismatches in the medium. In another embodiment, the Stokes wave energy omega s is generated by pump energy omega p in a first Raman cell and omega s, omega i and omega p are combined in a second Raman mixing cell to produce the output at omega i.