Abstract: A rotationally tunable time delay line device for providing a continually adjustable time delay between two orthogonally polarized laser pulses is described. The device is comprised of one or more rotational delay crystals, each made of a flat uniaxially birefringent crystal with a special orientation of its internal optical axis. The time delay generated between the two orthogonally polarized laser pulses that travel through the rotationally tunable delay line can be continually adjusted by rotating the constituent rotational delay crystals around their surface normals. An application is demonstrated in detail where the rotationally tunable time delay line device is used to form an optical autocorrelator for measuring femtosecond or picosecond duration laser pulses.

Abstract: An optical demultiplexer includes an optical loop having first and second terminals and a mid point. A non-linear optical element is positioned in the loop at a distance .DELTA.x from the mid point. A first coupler is positioned in the loop and has a gating pulse applied which causes a change in the optical property of the non-linear optical element from a first state to a second state. A second coupler is optically coupled to the first and second terminals and has an input terminal for receiving a series of input optical pulses. The second coupler responds by inducing, for each input pulse, a pair of counter-propagating pulses in the optical loop. Control circuitry causes a gating pulse to be applied to the optical loop and to be timed to switch the non-linear optical element to from a first to a second state after one of the pair of counter-propagating pulses has passed through the non-linear optical element, but before the other counter-propagating pulse has reached the non-linear optical element.