High birefringence D-type fibre loop mirror used as refractometer

A high birefringent D-type fibre loop mirror used as refractometer is reported. A chemical etching was applied to the D-type fibre and presented high sensitivity for the surrounding medium refractive index. The refractometer was tested with different refractive indices in liquids and characterized in temperature, showing a linear and independent response to both parameters. With these results the refractometer can perform simultaneous measurement of refractive index and temperature.