Laser Assembly And Inspection System Using Monolithic Bandwidth Narrowing Apparatus

摘要

A pulsed UV laser assembly includes a partial reflector or beam splitter that divides each fundamental pulse into two sub-pulses and directs one sub-pulse to one end of a Bragg grating and the other pulse to the other end of the Bragg grating (or another Bragg grating) such that both sub-pulses are stretched and receive opposing (positive and negative) frequency chirps. The two stretched sub-pulses are combined to generate sum frequency light having a narrower bandwidth than could be obtained by second-harmonic generation directly from the fundamental. UV wavelengths may be generated directly from the sum frequency light or from a harmonic conversion scheme incorporating the sum frequency light. The UV laser may further incorporate other bandwidth reducing schemes. The pulsed UV laser may be used in an inspection or metrology system.

主权项

1. A laser assembly comprising:
a fundamental laser configured to generate laser light pulses having a fundamental frequency disposed within a fundamental frequency bandwidth; a pulse dividing element configured to divide each laser light pulse into a pair of corresponding sub-pulses including a first sub-pulse and a second sub-pulse; at least one monolithic device configured such that the first sub-pulse of each pair of corresponding sub-pulses is converted into a first stretched sub-pulse having a positive chirp, and configured such that the second sub-pulse of each pair of corresponding sub-pulses is converted into a second stretched sub-pulse having a negative chirp; and a frequency mixing module configured to mix each first stretched sub-pulse with its corresponding said second stretched sub-pulse such that said mixing generates sum frequency light including sum frequency pulses having frequencies equal to two times the fundamental frequency.