Ultrashort pulse light generating method using raman resonator and its device

A method for periodically generating ultrashort multifrequency optical pulses by use of a Raman resonator comprising the steps of:

• injecting a continuous-wave laser beam of a predetermined frequency, serving as excitation light, into a resonator having a specific resonator length and containing a Raman frequency shifting medium having a rotational Raman shift frequency,
• generating a plurality frequencies from the injected beam by the Raman frequency shifting medium,
• said predetermined frequency and said resonator length being respective multiples of the rotational shift frequency and a corresponding wavelength of the rotational shift frequency in order to generate preferentially the plurality of frequencies as multiples of the rotational Raman shift frequency and which resonate within the resonator while frequencies generated by vibrating Raman shifting are suppressed, and
• phase locking the generated plurality of frequencies to periodically generate the ultrashort multifrequency optical pulses in accordance with a beat frequency between the generated plurality of frequencies.