Optical communication module and optical element for optical communication module

An optical communication module comprising:

• a first light-receiving element with a receiving surface in which a light flux with a wavelength λ1 emitted from an end surface of an optical fiber enters;
• a light-emitting element for emitting a light flux with a wavelength λ2 (λ1≠λ2);
• and
• a first optical element arranged between the first light-receiving element and the light-emitting element, and the end surface of the optical fiber, converging the light flux with the wavelength λ1 emitted from the end surface of the optical fiber on the receiving surface of the first light-receiving element, and converging the light flux with the wavelength λ2 emitted from the light-emitting element on the end surface of the optical fiber,
• wherein the first optical element comprises a first optical surface with a positive refractive power and a second optical surface having a diffractive structure generating a m-th order diffracted light flux with a larger light amount than any generated diffracted light fluxes with the other diffraction order when the light flux with the wavelength λ2 passes through the diffractive structure, and generating a n-th order diffracted light flux with a larger light amount than any generated diffracted light flux with the other diffraction order when the light flux with the wavelength λ1 passes through the diffractive structure, where m is 0, n is an integer excluding 0, and
• one of the first optical surface and the second optical surface is divided into a plurality of optical functional surfaces provided with at least one step difference extending along the optical axis, the plurality of optical functional surfaces include at least a first optical functional surface including an optical axis and a second optical functional surface surrounding the first optical functional surface through a step difference extending along the optical axis, a number of the divided optical functional surfaces is 2 or 3.