公开(公告)号：FR2366718A1

公开(公告)日：1978-04-28

申请号：FR7716045

申请日：1977-05-17

Applicant: IBM

Inventor： BENNETT ROBERT J ,  GRISCHKOWSKY DANIEL R

IPC: G02F1/17 ,  G02F1/01 ,  G02F1/35 ,  G02F2/02 ,  H01S3/10

Abstract: A dark pulse is manifested when the intensity of a laser beam, for example, a continuous wave laser beam drops to zero and returns to its original intensity in a very short time period. A modulator for producing dark pulse outputs is disclosed which includes a two-photon absorption cell provided with two input laser beams: a continuous wave beam having a frequency omega 1 and a mode-locked laser beam having a frequency omega 2 selected such that omega 1 + omega 2 = OMEGA 12 where OMEGA 12 is also the two-photon absorption frequency of the vapor contained in the cell. The mode locked beam modulates the continuous wave beam to produce the desired dark pulses.