OPTICAL ISOLATOR AND OPTICAL MODULE

• Main Author: IZUMI HIROTOMO
• Format: Patent
• Language: English; Japanese
• Published: 04.10.2018
• Subjects: OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

PROBLEM TO BE SOLVED: To provide an optical isolator that suppresses reduction in a shielding property against reflected light caused by temperature change.SOLUTION: An optical isolator 1 includes: an optical waveguide 11 having an input waveguide 21, a first branch waveguide 23, a second branch waveguide 24 and an output waveguide 25; a first coupler 12 that connects the input waveguide, the first branch waveguide and the second branch waveguide; a second coupler 13 that connects the output waveguide, the first branch waveguide and the second branch waveguide; a first phase adjusting plate 14 that adjusts the phase of light passing through a first route including the first branch waveguide, depending on the polarization state of the light; a second phase adjusting plate 15 that adjusts the phase of light passing through a second route including the second branch waveguide depending on the polarization state of the light; and a polarization conversion element 16 having a function of, when reflected light depending on output light enters the output waveguide, converting the polarization state of the reflected light in such a manner that phases of the light passing through the first route and of the light passing through the second route are opposite to each other in the input waveguide.SELECTED DRAWING: Figure 1 【課題】温度変化に起因した反射光の遮蔽性の低下を抑制する光アイソレータを提供する。【解決手段】光アイソレータ１は、入力導波路２１と、第１の分岐導波路２３と、第２の分岐導波路２４と、出力導波路２５とを有する光導波路１１と、入力導波路、第１の分岐導波路及び第２の分岐導波路を接続する第１のカプラ１２と、出力導波路、第１の分岐導波路及び第２の分岐導波路を接続する第２のカプラ１３と、第１の分岐導波路を含む第１の経路を通過する光の位相を当該光の偏波状態に応じて調整する第１の位相調整板１４と、第２の分岐導波路を含む第２の経路を通過する光の位相を当該光の偏波状態に応じて調整する第２の位相調整板１５と、出力光に応じた反射光が出力導波路へ入力される場合に、第１の経路を通過する光と第２の経路を通過する光とが入力導波路において逆相となる様に、反射光の偏波状態を変換する偏波変換素子１６とを有する。【選択図】図１