Anritsu Corporation

Nippon Telegraph and Telephone Corporation

Hiroshi Goto

Takeshi Tsukamoto

Yukio Tsuda

Hiroaki Endoh

Hiroaki Ohtateme

Youji Sonobe

Akihiko Asai

Youichi Tamura

Ko Ikeuchi

Yasutaka Ichihashi

Takamasa Imai

This invention is applied to an optical amplifier evaluation method of modulating by an optical modulator,light output from a light source,into a rectangular optical signal which is enabled/disabled in a predetermined period, then applying the optical signal to an optical fiber amplifier,to be measured, and obtaining the gain and noise figure of the optical fiber amplifier from the light intensities in the ON and OFF periods of an optical signal output from the optical fiber amplifier and the light intensity in the ON period of an optical signal input to the optical fiber amplifier. Output light from the optical fiber amplifier in a no-input state is passed through an optical path extending from the light source to the optical fiber amplifier and an optical path extending from the optical fiber amplifier to a light intensity measurement position, thereby obtaining optical losses on the respective optical paths. By the obtained optical losses, the light intensities are corrected. As a result, the gain G and noise figure NF of the optical fiber amplifier,can be attained with high precision.

Optical amplifier evaluation method and optical amplifier evaluation device

In an external-cavity tunable wavelength light source using a semiconductor laser (LD), an oscillation wavelength is tuned by simultaneously changing a current to be injected to the phase adjustment area of the LD and the rotation angle of a diffraction grating while holding the same external cavity longitudinal mode. A light beam emitted from the AR-coated end face of the LD having the phase adjustment area is collimated by a lens and incident on the diffraction grating. Only a light component having a specific wavelength selected upon spectral dispersion is reflected by the diffraction grating and returns to the LD. With this operation, an external cavity (effective cavity length K) is formed between the LD and the diffraction grating, thereby performing laser oscillation at a wavelength determined by an external cavity longitudinal mode and the cavity loss of the diffraction grating. The effective cavity length K can be changed in accordance with the current to be injected to the phase adjustment area. A current injection unit injects the current to the phase adjustment area. An oscillation wavelength control unit controls the injection current output from the current injection unit and the rotation angle of the diffraction grating.

External-cavity tunable wavelength light source using semiconductor

In an external-cavity tunable wavelength light source using a semiconductor laser (LD), when an interferometer serving as an optical filter is constituted by part of an external cavity, an external-cavity longitudinal mode can be selected with good reproducibility, and a side mode suppression ratio can be increased. A light beam emitted from an AR-coated facet of an LD is converted into a collimated beam by a lens, and the collimated beam is incident on a Mach-Zehnder (MZ) interferometer serving as an optical filter. An interference light beam emerges from the MZ interferometer toward a diffraction grating. Only a light component having a specific wavelength and selected by spectrally dispersing the interference light beam reversely travels in the same optical path as that of the interference light beam and is returned to the LD. In this manner, a cavity is formed between the LD and the diffraction grating, and a laser beam having a wavelength determined by three relationships between an external-cavity longitudinal mode, a cavity loss caused by the diffraction grating, and the output characteristics of an interference light beam from the MZ interferometer is oscillated.

Tunable wavelength light source incorporated optical filter using

Light wavelength measuring apparatus including an interference

Growing community of inventors

Isehara, Japan

Hiroshi Goto