sum frequency generation vibrational spectroscopy
cascaded sum-and difference-frequency generation
Extra-cavity sum-frequency
intra-cavity sum frequency
intracavity sum frequency mixing
Intracavity Sum-frequency
Intra-cavity sum-frequency mixing
Intracavity sum-frequency mixing
sum-frequency mixing laser
Difference frequency generation
Difference-Frequency Generation
Difference-frequency-generation
different frequency generation