Adv Antest Corporation

Other

Tohoku University

Fujitsu Corporation

National Institute of Advanced Industrial Science and Technology

Masataka Nakazawa

Kazunori Shiota

Masato Yoshida

Shin Masuda

Shigeki Watanabe

Haruo Yoshida

Hirokazu Matsumoto

Yoshio Hino

Masaru Arai

Akihito Suzuki

Toshihiko Hirooka

Provided is a laser apparatus including: a DFB fiber laserincluding, as an amplitude medium, a rare earth doped silica optical fiber codoped with a high concentration of aluminum; an optical feedback pathformed by a ring-shaped optical fiber; and an optical couplera) feeding back a part of an output of the DFB fiber laserto the DFB fiber laservia the optical feedback path, and b) outputting, to outside, another part of the output of the DFB fiber laser, where the optical fiber forming the optical feedback pathis longer than a length at which a relaxation oscillation noise in the output to the outside becomes &#x2212;110 dB/Hz.

Laser apparatus

A laser oscillator includes a ring resonator. The ring resonator includes an optical circulator having first, second, third, and fourth ports and a first optical amplification fiber connected to the optical circulator. Light incident on the first port is exited from the second port, and light incident on the second port is exited from the third port. The fourth port provides an exciting light and injects the exciting light into the ring resonator through the first port. The first optical amplification fiber amplifies light exited from the third port with the exciting light provided by the fourth port. The laser oscillator also includes an optical member connected to the optical circulator. The optical member reflects at least a part of the light exited from the second port and injects the same into the second port again.

Laser oscillator

The phase modulation in which the frequency chirp becomes 0 at the timing which the user wants to synchronize, and the frequency chirp becomes larger as the time deviates in a positive or negative direction from this timing is applied to the signal light with each wavelength comprising pulse train of different timing. Thus, the optical pulses which deviate from the timing which the user wants to synchronize receive the frequency chirp in accordance with the amount of the timing deviation. The WDM signal light which has been chirped in this way is made to pass a linear dispersive medium, and the dispersion fit for the amount of frequency chirp is made to be given. By adjusting the amount of dispersion, it is possible to obtain the pulses which conform to the timing at which the user wants to synchronize the pulses of each wavelength.

Optical synchronizer

To extend the temperature range for a stable operation without mode hopping and obtain a stable laser oscillation, a laser oscillator is provided. The laser oscillator includes: an optical circulator in which light incident on a first port is exited from the second port, light incident on the second port is exited from a third port, and light incident on a fourth port is exited from the first port; a first optical amplification fiber that amplifies the light exited from the third port because of being excited by an exciting light and injects the same into the first port; a reflective optical filter that reflects light with a predetermined wavelength among the light exited from the second port and injects the same into the second port again; and an pump light source that generates an exciting light to excite the first optical amplification fiber. The reflective optical filter transmits light oscillated by laser in a ring resonator including the first optical amplification fiber, the optical circulator and the reflective optical filter and outputs the same. The pump light source injects the exciting light from the fourth port into a ring resonator.

In a measuring-instrument remote-calibration system and measuring-instrument remote-calibration method, a measuring standard quantity is converted into a parameter adapted for communication, or based on measuring standard quantity, a parameter adapted for communication is generated and sent to a remote place. Alternatively, when the measuring standard quantity is not suitable for communication, it is converted into a form adapted for transportation and the converted measuring standard quantity is sent to a remote place. After the converted measuring standard quantity reaches the place, it is restored to the original measuring standard quantity, thus enabling calibration. The result of the calibration is certified.

Measuring-instrument remote-calibration system and measuring-instrument remote-calibration method

Growing community of inventors

Miyagi, Japan

Masataka Nakazawa