Method and apparatus for phase matching by adjustment of the fundamental frequencies
AssigneeBell Telephone Laboratories, Incorporated
InventorsJohn Ernst Bjorkholm, Gary Carl Bjorklund, Paul Foo-Hung Liao
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Abstract
A method and apparatus for phase-matching the output of a four-wave nonlinear optical mixing process is disclosed. The method produces phase-matching that is independent of variations in density of the conversion medium and extends over the entire frequency spectrum from the far infrared to the vacuum ultraviolet. The phase-matching is accomplished by adjustment of the frequencies of three input lasers so that the desired frequency is produced, the condition for two-photon resonance enhancement is met, and the phase-matching condition is satisfied.
Claims8
An apparatus for generating an output frequency .omega..sub.4 comprising:
- first, second, and third lasers for generating input beams having frequencies .omega..sub.1, .omega..sub.2, and .omega..sub.3, respectively, the extremes of which frequencies define a frequency range,
- an interaction medium having at least one two-photon resonance coupled to the ground state of said interaction medium and at least one strong one-photon resonance coupled to the ground state of said interaction medium, the frequency of which one-photon resonance is within said frequency range,
- means for directing said beams of said first, second and third lasers substantially collinearly onto said interaction medium, and
- means for extracting said output frequency .omega..sub.4 from said interaction medium,
- characterized in that the frequencies of said first, second, and third lasers are adjusted to satisfy three conditions simultaneously:
- the output frequency .omega..sub.4 is equal to a linear combination of .omega..sub.1, .omega..sub.2 and .omega..sub.3 ;
- the frequency of said two-photon resonance is nearly equal to a linear combination of .omega..sub.1 and .omega..sub.2 ;
- and the phase-matching equation is substantially satisfied by .omega..sub.1, .omega..sub.2, .omega..sub.3 and .omega..sub.4, whereby said first, second and third lasers perform the function of phase-matching the output frequency in addition to performing the function of providing said frequencies .omega..sub.1, .omega..sub.2 and .omega..sub.3 which combine to form said output frequency.
A method of generating an output frequency .omega..sub.4, comprising the steps of:
- a. combining collinearly the beams from a first, second and third input laser, which beams are of frequency .omega..sub.1, .omega..sub.2 and .omega..sub.3, respectively,
- b. directing the combined beams onto an interaction medium having at least one two-photon resonance and at-least one strong one-photon resonance within a frequency range defined by the frequencies of said input lasers,
- c. setting the frequencies of said first, second and third input lasers to predetermined values such that three conditions are simultaneously satisfied:
- the output frequency .omega..sub.4 is equal to a linear combination of .omega..sub.1, .omega..sub.2 and .omega..sub.3 ;
- the frequency of said two-photon resonance is nearly equal to a linear combination of .omega..sub.1 and .omega..sub.2 ;
- and the phase-matching equation is substantially satisfied by .omega..sub.1, .omega..sub.2, .omega..sub.3 and .omega..sub.4, whereby said first, second and third lasers perform the function of phase-matching the output frequency in addition to performing the function of providing frequencies .omega..sub.1, .omega..sub.2 and .omega..sub.3 and
- d. extracting said output frequency from said interaction medium.
Dependencies are inferred from the claim text.