Optical signal amplifying triode and optical signal transfer method, optical signal relay device, and optical signal storage device using the same

An optical signal amplifying triode comprising:

• a first semiconductor optical amplifier and a second semiconductor optical amplifier, each equipping an active layer formed of a pn junction and amplifying, performing wavelength conversion on, and then outputting an optical signal input therein;
• a first optical input means, inputting a first input light of a first wavelength and a second input light of a second wavelength into the first semiconductor optical amplifier;
• a first wavelength selector, selecting light of the second wavelength from among the light from the first semiconductor optical amplifier;
• a second optical input means, inputting the light of second wavelength that has been selected by the first wavelength selector and a third input light of a third wavelength into the second semiconductor optical amplifier;
• and
• a second wavelength selector, selecting output light of the third wavelength from among the light from the second semiconductor optical amplifier;
• and
• being characterized in that the output light of the third wavelength is modulated in response to the intensity variation of either or both of the first input light of the first wavelength and the third input light of the third wavelength and the signal gain with respect to the third input light of the third wavelength is 2 or more.