Variable optical delay circuit

A variable optical delay circuit, comprising:

• a birefringent member;
• a variable optical rotator for varying a polarization state of an outputted light from said birefringent member;
• and
• a reflecting mirror for reflecting an outputted light from said variable optical rotator toward said variable optical rotator and said birefringent member,
• said birefringent member, said variable optical rotator and said reflecting mirror being disposed on the same optical axis, and an optical axis of said birefringent member being set so as to perpendicularly or almost perpendicularly intersect a traveling direction of inputted light.

A variable optical delay apparatus comprising:

• a first birefringent member receiving a light and separating the received light into first and second polarization components perpendicular to each other in accordance with a crystal axis of the first birefringent member;
• and
• a variable optical rotator rotating polarization of the first and second polarization components;
• and
• a second birefringent member receiving the polarization rotated first and second polarization components and transmitting therethrough the received polarization rotated first and second polarization components in accordance with a crystal axis of the second birefringent member, wherein
• the first birefringent member, the variable optical rotator and the second birefringent member are disposed on a same optical axis,
• the crystal axis of the first birefringent member is disposed with respect to said same optical axis so that the first and second polarization components are not spatially separated from each other by the first birefringent member, and
• the crystal axis of the second birefringent member is disposed with respect to said same optical axis so that the polarization rotated first and second polarization components are not spatially separated from each other by the second birefringent member.