Optical transmission apparatus and laser pulse duration expander

An optical transmission apparatus comprising: a beam divider e.g. microlens array 203; fibre-optic bundle having a plurality of optical fibres 209a-d for receiving divided portions of the beam; and a beam combiner e.g. microlens array 211 for combining divided portions of the beam received from the bundle wherein at least two of the optical fibres have different optical path lengths e.g. due to different physical lengths or different refractive indices. The beam 201 may be from a pulsed laser. Also provided is a laser pulse duration expander having such a fibre-optic bundle so that input of a laser pulse with a first pulse duration results in the output of a combined pulse with a second pulse duration greater than the first. The laser may be a Q-switched laser.