Patent ID: 8441249

Claim:
A voltage measurement device comprising: a holder for arrangement between two potentials; a first waveguide transversally poled in a first poling direction; a second waveguide transversally poled in a second poling direction, wherein said first and second waveguides are of identical type and are arranged parallel to one other for each carrying at least one optical mode having two orthogonal light polarization directions, and wherein said first and second waveguides are supported on said holder with said first and said second poling directions being anti-parallel; a coupling between said first and said second waveguides for exchanging said orthogonal light polarization directions of the optical modes in the first and in the second waveguides such that a photon running along one of the first and second waveguides and being polarized along a slow axis of the one waveguide is coupled to a photon being polarized along a fast axis of the other of the first and second waveguides and vice versa; a control unit for sending light at least once through said first waveguide, said coupling and said second waveguide for measuring a phase delay between: light waves that travel through said first waveguide with a polarization along the first poling direction and through said second waveguide with a polarization perpendicular to said second poling direction, and light waves that travel through said first waveguide with a polarization perpendicular to said first poling direction and through the second waveguide with a polarization along said second poling direction; and a Faraday rotator with a rotation angle per pass of 45°+k*90°, with k being any integer number, arranged between the control unit and the first waveguide.