Optical: systems and elements – Optical amplifier – Optical fiber
Reexamination Certificate
2000-03-17
2002-03-05
Tarcza, Thomas H. (Department: 3662)
Optical: systems and elements
Optical amplifier
Optical fiber
C359S244000
Reexamination Certificate
active
06353498
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical function device, and more particularly, to a new optical function device which is capable of executing logical operation and optical amplification of optical signal as well as image optical signal and is capable of being operated in a wide temperature range, and thus can be used preferably in optical electronics such as optical communication, optical image processing or optical computer capable of high-level information processing.
2. Description of the Related Art
In an optical communication of recent years, an optical signal is amplified by using an erbium-doped fiber or a crystal, and the optical signal is transferred over a long distance without any electric amplifier, thereby carrying out a high-level information transmission.
On the other hand, there has been developed an optical element for inverting an optical signal by using the negative nonlinear absorption effect of erbium ions (for example, see “All-optical inverter operating over a temperature range of 15-1400K in erbium-doped lutetium aluminum garnet”, by Yoshinobu Maeda, Applied Physics Letters, Volume 72, pp395-397).
However, the conventional erbium-doped fiber or crystal has no function of optical operation of an optical signal. The conventional optical element using the negative nonlinear absorption (NNA) has no function or effect of optical amplification of an optical signal. In addition, there has not been developed, for an optical communication wavelength band (1.5 &mgr;m), any optical element capable of controlling an image optical signal directly by another image optical signal and operable in low to high temperatures.
SUMMARY OF THE INVENTION
In view of the foregoing, it is the main object of the present invention to provide a new optical function device which is capable of inverting and amplifying an optical signal of the optical communication wavelength band, and executing operation of an image optical signal, and is operable in a wide temperature range.
The above and other objects, advantages and features of the present invention are accomplished by a optical function device. An optical function device composed of a light transmitting medium containing a rare earth element, comprising a portion thereof doped with 1×10
23
per 1 m
3
or more of the rare earth element for executing an inversion of an optical signal, a portion thereof doped with 1×10
21
per 1 m
3
or more of the rare earth element for executing an amplification of the optical signal with an excitation light superposed thereto.
In a further aspect of the invention, the rare earth element is Er (erbium), a wavelength of the optical signal falls in a range of 1.5 &mgr;m ~1.6 &mgr;m, and a wavelength of the excitation light is 0.98 &mgr;m band or 1.48 &mgr;m band or 0.8 &mgr;m band.
In another aspect of the present invention, said optical function device is operated in a temperature range of at least −100° C. ~300° C.
REFERENCES:
patent: 5434701 (1995-07-01), Fatehi et al.
patent: 5537243 (1996-07-01), Fatehi et al.
patent: 5742072 (1998-04-01), Maeda
Y. Maeda et al., “Negative nonlinear absorption effects in erbium-yttrium aluminum garnets”, Journal of Applied Physics, vol. 72, No. 8, Oct. 15, 1992, pp. 3835-3837.
Y. Maeda et al., “Negative light-modulation effect of boron-doped hydrogenated amorphous silicon”, Applied Physics Letters, vol. 59, No. 4, Jul. 22, 1991, pp. 390-392.
Y. Maeda et al., “Bistable optical devices with laser diodes coupled to absorbers of narrow spectral bandwidth”, Applied Optics, vol. 33, No. 18, Jun. 20, 1994, pp.4077-4081.
Y. Maeda et al., “All-optical inverter operating over a temperature rane of 15-1400 K in erbium-doped lutetium aluminum garnet”, Applied Physics Letters, vol. 72, No. 4, Jan. 26, 1998, pp. 395-397.
Hughes Deandra
National Space Development Agency of Japan
Tarcza Thomas H.
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