POLARIZATION INDEPENDENT OPTICAL ISOLATOR

PROBLEM TO BE SOLVED: To eliminate a crystal plate with a WDM film and to equalize a lens constituting a collimator so as to obtain a WDH module which is small and superior in mass-productivity by forming the WDM film on one surface of one Faraday rotary element and executing the AR coating of a two-wave length band on both surfaces of plural complex refraction crystal plates. SOLUTION: The WDM film is formed on one surface of the one Faraday rotary element and two-wave length band AR coating is executed on both surfaces of more than one complex refraction crystal plates. Then, the function of an optical isolator and the function as the optical parts of the WDM module are provided. For example, an optical isolator WDM module consists of a fiber 4 for the incidence of a signal light λ2 and the reception of an exciting light λ1, the fiber 5 for the incidence of λ1, the collimatoar 6 for receiving λ1, the complex refraction crystal plate 9 where the AR coating for the two-wave length band of λ2 is executed on both surfaces and the Faraday rotary element 10 where the WDH film where reflection is executed in λ1 and transmission is executed in λ2 on the one side surface is formed and also AR coating for λ2 is executed on the other side surface, etc.