Anritsu Corporation

Hiroshi Komazawa

Hideyuki Sakamoto

Yukio Tsuda

Kenichiro Umesaki

Yuuichi Watanabe

Fuminobu Ito

Yoshiharu Sasaki

In an optical amplifier evaluating system of this invention, a pulse method using optical modulators and a probe method are combined to obtain a gain G and noise figure NF of an optical fiber amplifier. A first optical modulator turns on and off signal light output from a first light source. An optical multiplexer multiplexes the optical signal turned on and off by the first optical modulator and probe light output from a second light source. This optical signal multiplexed by the optical multiplexer is selectively fed into an optical fiber amplifier. A controller properly switches optical path switches to allow an optical spectrum analyzer to measure (1) the light intensity of an input signal of the probe light to the optical fiber amplifier, (2) the light intensity in a region where signal light extracted from the output signal light from the optical fiber amplifier by a second optical modulator is in an OFF period and the probe light is output, and (3) the light intensity in a region where the signal light extracted by the second optical modulator is in the OFF period and no probe light is output. On the basis of measured light intensities (1), (2), and (3), the controller calculates the gain G and noise figure NF of the optical fiber amplifier. In this manner, the optical amplifier evaluating system of this invention can accurately obtain the gain G and noise figure NF of the optical fiber amplifier.

Optical amplifier evaluating method and optical amplifier evaluating apparatus

To know an optical path switching error, a stepping motor is rotated at a predetermined angular step so as to couple an optical fiber collimator attached to its rotating shaft to an optical fiber collimator of optical fiber collimators that is designated by a designation signal. The direction of the optical axis of the optical fiber collimator is detected by a slit disk attached to the rotating shaft, and sensors for detecting slit arrays formed in the slit disk. Detection signals from the sensors are determined to correspond to the designation signal.

Optical switch capable of detecting switching operation

A first optical attenuation filter is arranged in a predetermined optical path and attenuates light to be attenuated with a first variable attenuation amount. A second optical attenuation filter is arranged in the predetermined optical path and attenuates, with a second variable attenuation amount, the light which has been transmitted through the first optical attenuation filter. The first and second optical attenuation filters can be driven in the forward and reverse directions and each has an attenuation amount characteristic which changes monotonously in both the forward and reverse directions. An attenuation amount setting section sets a desired attenuation amount to the light to be attenuated. First and second drivers are coupled to drive the first and second optical attenuation filters in the forward and reverse directions, respectively. A controller controls driving directions and driving amounts of the first and second optical attenuation filters through the first and second drivers in accordance with the desired attenuation amount so that an algebraic sum of the first and second attenuation amounts finally becomes equal to the desired attenuation amount and a variation in attenuation amount is decreased as a whole, thereby providing a smooth attenuation characteristic.

Growing community of inventors

Isehara, Japan

Hiroshi Komazawa