Improved coupling between laser diode and single-mode fibre tipped with a chemically etched self-centred diffracting element

Coupling efficiency between a laser diode and single-mode fibre can be highly increased by using an appropriate intermediate optical element. A simple new method is intended to improve the mode matching of the two elements by chemically etching the fibre end into a self-centred diffracting element. A gain by a factor of 3.5 over classical butt coupling has been obtained.