AMPLIFICATION APPARATUS NONSENSITIVE TO POLARIZED LIGHT

摘要

PURPOSE: To provide a compact unit without the use of a lens by constructing a reciprocal reflector with a retarding device and a mirror disposed rearwardly. CONSTITUTION: An input signal of an amplifier is fed to one port of a circulator C, and reaches an optical amplifier through an adjacent port. The amplified input signal after having been amplified by an optical amplifier OA reaches a λ/4 retarding device R, together with a retarded component of the input signal. The signal after being reflected by the mirror S passes oppositely again through the retarding device R and the amplifier OA. The amplifier reflected signal rs appears at an input part of the optical amplifier and is discriminated by the circulator C from the input signal is. The amplified reflected signal rs can be taken out as an output signal os amplified at a third port. Hereby, a compact unit is ensured without the use of a lens.