Patent ID: 7121741

Claim:
An optical communication module comprising: an optical fiber having an end face inclined at a tilt angle θ with respect to a plane perpendicular to an axis of the optical fiber; a light receiving device to receive light of wavelength λ 1 emitted from the end face of the optical fiber; a light emitting device to emit light of wavelength λ 2 (λ 1 ≠λ 2 ) to allow the light to enter the end face of the optical fiber; a first optical element positioned between the light receiving device as well as the light emitting device and the end face of the optical fiber; a second optical element positioned between the light emitting device and the first optical element; wherein the first optical element has a curved optical surface facing the light receiving device and facing the light emitting device, and the first optical element also has a flat optical surface facing the end face of the optical fiber; wherein a diffraction structure is formed on the flat optical surface such that when the light of wavelength λ 2 passes through the diffraction structure, zero-th order diffraction light has a largest quantity of light, and when the light of wavelength λ 1 passes through the diffraction structure, n-th order diffraction light has a largest quantity of light (“n” is an integer excluding zero) and; wherein the light of wavelength λ 1 enters the diffraction structure in the state of being inclined with respect to an axis of the first optical element such that the n-th order diffraction light generated in the diffraction structure travels along or parallel to the axis of the first optical element.