OPTICAL TRANSMISSION MODULE AND OPTICAL TRANSMISSION DEVICE MOUNTED WITH THE SAME

摘要

PROBLEM TO BE SOLVED: To optically communicate high-speed signals by providing a diffraction grating with a specific diffraction grating pattern. ;SOLUTION: When a light reception point A on a photodiode, the light emission point B of a semiconductor laser, and the diffraction grating 3 are arranged, this diffraction grating 3 has a diffraction pattern satisfying relation, represented as a function (x²+y²-2yf₁sinθ+f₁²)^1/2-(x²+y²+f₂²)^1/2=mλ, with the center axis of its diffraction grating surface. Here, f₁ is the distance (μm) from the center of the diffraction grating to a 1st light convergence point of the diffraction grating in the end surface direction of a light receiving element or light emitting element, f₂ is the distance (μm) from the center of the diffraction grating to a 2nd light convergence point of the diffraction grating in the end surface direction of the light emitting element or light receiving element, θis the angle between the straight line connecting the center of the diffraction grating and the 1st light convergence point of the diffraction grating and the straight line connecting the center and 2nd light convergence point of the diffraction grating, (m) is an integer, λ is the wavelength (μm) of a light beam, and (x) and (y) are the coordinates from the center of a diffraction grating plane.;COPYRIGHT: (C)1998,JPO