Patent ID: 9372310
Filing Date: 2016-06-21
CPC Classification: G02B,G02F

Claim Text:
1. A method of free space fibre-to-fibre coupling, comprising: providing a first optical fibre and a second optical fibre spaced apart from one another by a free space distance having a pair of spaced-apart achromatic collimating lenses within said free space distance, and launching essentially single mode light from said first optical fibre at a wavelength λ or a range of λs that provides at least a portion of its light at wavelength(s) below a cut-off wavelength for said first optical fibre, wherein said first optical fibre and said second optical fibre are both <50 m and sufficiently short to provide essentially single mode operation, and wherein said essentially single mode light after said launching propagates as free space light through said free space distance and is received by and propagates in said second optical fibre as said essentially single mode light.