Method of measuring a mode partition characteristics of a laser diode and an apparatus of the same

DETAILED DESCRIPTION It is accordingly an object of the present invention to provide a measuring apparatus and a method for measuring mode partition characteristics of laser diode under the condition near the actual drive condition.
According to one aspect of the present invention, an apparatus is provided for measuring a mode partition characteristics of a laser diode comprising a first means driven by he clock signal of period T, for generating N bit-length of pseudo noise, an optoelectric conversion means including a laser diode to be measured, for outputting optical signal modulated by said pseudo noise pattern, a second means for separating a particular longitudinal mode from said optical signal, a third means for detecting power P.
sub.
i of said particular longitudinal mode, a fourth means for detecting a line spectral element w.
sub.
line (f) and continuous spectral element w.
sub.
cont (f)' of said particular longitudinal mode, and a processing means for calculating a coefficient which indicates mode partition characteristics by obtaining a relative power a.
sub.
i of said particular longitudinal mode in all longitudinal modes, a ratio of line spectral element to continuous spectral element and a coefficient defined by a number of N-bits of pseudo noise.
According to another aspect of the present invention, a method of measuring mode partition characteristics of a laser diode is providing comprising the following steps; modulating said laser diode by pseudo noise with a period NT, measuring relative intensity of particular longitudinal mode in all longitudinal modes of output optical signal of said laser diode, measuring line spectral element and continuous spectral element of said particular longitudinal mode, and calculating a coefficient whch indicates a mode partition characteristics of said laser diode from measured values and a coefficient defined by N of pseudo noise.