An arrangement for optical fibre communications, for used, e.g., in millimetre (MM) fibre transmission systems includes: a source (1) of optical radiation defining an offset launch path of optical radiation (R) into an optical fibre (F), and at least one active element (3,4; 6; 7) actuatable to selectively vary said offset launch path in order to achieve an adjustable offset launch of said optical radiations (R) into said optical fibre (F).