Three-terminal optical signal amplifying device

Abstract

In the three-terminal optical signal amplifying device 10, a portion of the neighboring light L S at other wavelength than that of the first wavelength λ 1 that is selected from the output light from the element 14 by the optical add drop filter 16 , and the control light L C at the second wavelength λ 2 input from the external are together input to the second semiconductor optical amplifying element 18. The output light including the output signal light L OUT at the second wavelength λ 2 and the neighboring light at the neighboring wavelength to the second wavelength λ 2 that is modulated and controlled by the control light L C in the cross gain modulation is output from the second semiconductor optical amplifying element 18. And the output signal light L OUT at the second wavelength λ 2 passes through the wavelength selecting filter 20.

1 . A three-terminal optical signal amplifying device comprising:
 a first semiconductor optical amplifying element and a second semiconductor optical amplifying element, each being provided with an active layer constituted by a p-n junction;   a first input means to input a first input light of a first wavelength to the first semiconductor optical amplifying element;   a first wavelength selecting element which selects a total or a predetermined portion of a wavelength band of a neighboring light of other wavelength than the first wavelength, from a light which is output from the first semiconductor optical amplifying element;   a second input means to input a second input light of a second wavelength to the second semiconductor optical amplifying element, together with a light of the total or the predetermined portion of the wavelength band of the neighboring light of other wavelength than the first wavelength which is selected by the first wavelength selecting element; and   a second wavelength selecting element which selects a light of the second wavelength, from a light which is output from the second semiconductor optical amplifying element,   the first input light of the first wavelength being an input light which is intensity-modulated;   the second input light of the second wavelength being a control light; and   an output light of the second wavelength having a signal waveform which is obtained by intensity-modulating the first input light during an input of the control light.   
     
     
         2 . The device according to  claim 1 , wherein the second wavelength is equal to the first wavelength. 
     
     
         3 . The device according to  claim 1 , wherein a gain of the output light of the second wavelength with respect to the control light of the second wavelength is not smaller than 10. 
     
     
         4 . The device according to  claim 1 , wherein the first wavelength selecting element and/or the second wavelength selecting element is a wavelength selecting filter which selects a light of which a spectrum range extends over not less than 5 nm. 
     
     
         5 . The device according to  claim 1 , wherein the first wavelength selecting element and the second wavelength selecting element are constituted by one of a grating filter and a multilayer filter, the grating filter being formed such that a portion of the grating filter is effected to have a periodical change in the refractive index, and the multilayer filter being formed so that a plurality of pairs of layers that have different refractive indices from each other are laminated in the multilayer filter. 
     
     
         6 . The device according to  claim 5 , wherein the grating filter is constituted by a graded period diffraction grating. 
     
     
         7 . The device according to  claim 1 , wherein the active layer of the first wavelength selecting element and/or the second wavelength selecting element is constituted by a quantum well, a strained superlattice or a quantum dot. 
     
     
         8 . The device according to  claim 1 , wherein the first wavelength selecting element and/or the second wavelength selecting element is provided on its one end face with a reflection means to reflect a light which has passed through the active layer, and an input light is input through another end face. 
     
     
         9 . The device according to  claim 8 , wherein the reflection means is a Bragg diffraction grating or a multilayer filter in which a plurality of pairs of layers that have different refractive indices from each other are laminated. 
     
     
         10 . The device according to  claim 1 , wherein the first input means and/or the second input means is constituted by an optical circulator, a directional coupled device, or an optical add drop filter. 
     
     
         11 . The device according to  claim 1 , wherein the three-terminal optical signal amplifying device is provided in an optical computing element, a wavelength division multiplexing optical repeater, or an optical memory.