Light amplification device

Claim 2

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for sweeping a transmission center wavelength of said bandpass filter in a predetermined band at a predetermined speed; a photoelectric converter for converting an intensity of the optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing second-order differentiation on the electrical signal converted by said photoelectric converter using time as a variable, and for generating a differentiated value representative of said second-order differentiation; and sweep stop means for receiving said differentiated value from said differentiating circuit and for supplying control signals to said controllable transmission center wavelength sweep means to cause said transmission center wavelength sweep means to stop sweep of the transmission center wavelength of said bandpass filter when the differentiated value generated by said differentiating circuit has a negative peak.

Claim 3

A device according to claim 1, wherein said light amplifier comprises a rare-earth-doped fiber as an amplification medium.

Claim 4

A device according to claim 1, wherein said light amplifier is a semiconductor optical amplifier.

Claim 5

A device according to claim 1, wherein said bandpass filter is a fiber type Fabry-Perot filter constituted by two opposing optical fibers whose opposing end faces are covered with half mirrors, and said transmission center wavelength sweep means comprises a piezoelectric actuator for changing a gap between said opposing end faces of said fiber of said fiber type Fabry-Perot fiber.

Claim 6

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for repeatedly sweeping a transmission center wavelength of said bandpass filter at a predetermined speed in a band of several fractions of a nm which is initially set and includes the wavelength of the optical signal; a photoelectric converter for converting an intensity of the optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing first-order differentiation on the electrical signal converted by said photoelectric converter using time as a variable, and for generation a differentiated value representative of said first-order differentiation; and sweep center wavelength change means for receiving said differentiated value from said differentiating circuit and for supplying control signals to said controllable transmission center wavelength sweep means for commanding said transmission center wavelength sweep means to change a transmission center wavelength of said bandpass filter obtained when the differentiated value generated by said differentiating circuit becomes "0" as a center wavelength of a band subjected to a next sweep by said transmission center wavelength sweep means.

Claim 7

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for repeatedly sweeping a transmission center wavelength of said bandpass filter at a predetermined speed in a band of several fractions of a nm which is initially set and includes the wavelength of the optical signal; a photoelectric converter for converting an intensity of the optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing first-order differentiation on the electrical signal converted by said photoelectric converter using time as a variable, and for generation a differentiated value representative of said first-order differentiation; and sweep center wavelength change means for receiving said differentiated value from said differentiating circuit and for supplying control signals to said controllable transmission center wavelength sweep means for commanding said transmission center wavelength sweep means to change a transmission center wavelength of said bandpass filter obtained when the differentiated value generated by said differentiating circuit becomes "0" as a center wavelength of a band subjected to a next sweep by said transmission center wavelength sweep means.

Claim 8

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for sweeping a transmission center wavelength of said bandpass filter in a predetermined band at a predetermined speed; a photoelectric converter for converting an intensity of the optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing first-order differentiation and second-order differentiation on the electrical signal converted by said photoelectric converter using time as a variable, and for generating first-order and second order differentiation values representative of said first and second-order differentiations, respectively; narrow-band sweep means for receiving said second-order differentiation value from said differentiation circuit and for repeatedly sweeping a transmission center wavelength of said bandpass filter at a predetermined speed in a band of several fractions of a nm using a transmission center wavelength of said bandpass filter obtained when a negative peak value of the second-order value generated by said differentiating circuit is detected as a center; and sweep center wavelength setting means receiving said first-order differentiation value from said differentiation circuit and for setting a transmission center wavelength of said bandpass filter obtained when the first-order value generated by said differentiating circuit becomes "0" to a center wavelength of a band subjected to a next sweep by said narrow-band sweep means while a transmission center wavelength is repeatedly swept by said narrow-band sweep means.

Claim 9

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for sweeping a transmission center wavelength of said bandpass filter in a predetermined band at a predetermined speed; a photoelectric converter for converting an intensity of the optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing first-order differentiation and second-order differentiation on the electrical signal converted by said photoelectric converter using time as a variable, and for generating first-order and second order differentiation values representative of said first and second-order differentiations, respectively; narrow-band sweep means for receiving said second-order differentiation value from said differentiation circuit and for repeatedly sweeping a transmission center wavelength of said bandpass filter at a predetermined speed in a band of several fractions of a nm using a transmission center wavelength of said bandpass filter obtained when a negative peak value of the second-order value generated by said differentiating circuit is detected as a center; and sweep center wavelength setting means receiving said first-order differentiation value from said differentiation circuit and for setting a transmission center wavelength of said bandpass filter obtained when the first-order value generated by said differentiating circuit becomes "0" to a center wavelength of a band subjected to a next sweep by said narrow-band sweep means while a transmission center wavelength is repeatedly swept by said narrow-band sweep means.

Claim 10

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; an optical signal branching unit for branching the optical signal from said bandpass filter into first and second branched optical signals; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for sweeping a transmission center wavelength of said first branched optical signal in a predetermined band at a predetermined speed; a photoelectric converter for converting an intensity of said second branched optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing second-order differentiation of the electrical signal converted by said photoelectric converter using time as a variable, and for generating a differentiated value representative of said second-order differentiation; and sweep stop means for receiving said differentiated value from said differentiating circuit and for supplying control signals to said controllable transmission center wavelength sweep means to cause said transmission center wavelength sweep means to stop sweep of the transmission center wavelength of said first branched optical signal when the differentiated value generated by said differentiating circuit has a negative peak.

Claim 11

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; an optical signal branching unit for branching the optical signal from said bandpass filter into first and second branched optical signals; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for sweeping a transmission center wavelength of said first branched optical signal in a predetermined band at a predetermined speed; a photoelectric converter for converting an intensity of said second branched optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing second-order differentiation of the electrical signal converted by said photoelectric converter using time as a variable, and for generating a differentiated value representative of said second-order differentiation; and sweep stop means for receiving said differentiated value from said differentiating circuit and for supplying control signals to said controllable transmission center wavelength sweep means to cause said transmission center wavelength sweep means to stop sweep of the transmission center wavelength of said first branched optical signal when the differentiated value generated by said differentiating circuit has a negative peak.

Claim 12

A device according to claim 7, wherein said light amplifier comprises a rare-earth-doped fiber as an amplification medium.

Claim 13

A device according to claim 7, wherein said light amplifier is a semiconductor optical amplifier.

Claim 14

A device according to claim 7, wherein said bandpass filter is a fiber type Fabry-Perot filter constituted by two opposing optical fibers whose opposing end faces are covered with half mirrors, and said transmission center wavelength sweep means comprises a piezoelectric actuator for changing a gap between said opposing end faces of said fiber of said fiber type Fabry-Perot fiber.

Claim 15

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; an optical signal branching unit for branching the optical signal from said bandpass filter into first and second branched optical signals; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for repeatedly sweeping a transmission center wavelength of said first branched optical signal at a predetermined speed in a band of several fractions of a nm which is initially set and includes the wavelength of the optical signal; a photoelectric converter for converting an intensity of said second branched optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing first-order differentiation on the electrical signal converted by said photoelectric converter using time as a variable, and for generating a differentiated value representative of said first-order differentiation; and sweep center wavelength change means for receiving said differentiated value from said differentiating circuit and for supplying control signals to said controllable transmission center wavelength sweeps means for commanding said transmission center wavelength sweep means to change a transmission center wavelength of said first branched optical signal obtained when the differentiated value generated by said differentiating circuit becomes "0" as a center wavelength of a band subjected to a next sweep by said transmission center wavelength sweep means.

Claim 16

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; an optical signal branching unit for branching the optical signal from said bandpass filter into first and second branched optical signals; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for repeatedly sweeping a transmission center wavelength of said first branched optical signal at a predetermined speed in a band of several fractions of a nm which is initially set and includes the wavelength of the optical signal; a photoelectric converter for converting an intensity of said second branched optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing first-order differentiation on the electrical signal converted by said photoelectric converter using time as a variable, and for generating a differentiated value representative of said first-order differentiation; and sweep center wavelength change means for receiving said differentiated value from said differentiating circuit and for supplying control signals to said controllable transmission center wavelength sweeps means for commanding said transmission center wavelength sweep means to change a transmission center wavelength of said first branched optical signal obtained when the differentiated value generated by said differentiating circuit becomes "0" as a center wavelength of a band subjected to a next sweep by said transmission center wavelength sweep means.

Claim 17

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; an optical signal branching unit for branching the optical signal from said bandpass filter to first and second branched optical signals; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for sweeping a transmission center wavelength of said bandpass filter in a predetermined band at a predetermined speed; a photoelectric converter for converting an intensity of said second branched optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing first-order differentiation and second-order differentiation on the electrical signal converted by said photoelectric converter using time as a variable, and for generating first-order and second order differentiation values representative of said first and second-order differentiations, respectively; narrow-band sweep means for receiving said second-order differentiation value from said differentiation circuit and for repeatedly sweeping a transmission center wavelength of said first branched optical signal at a predetermined speed in a band of several fractions of a nm using a transmission center wavelength of said first branched optical signal obtained when a negative peak value of the second-order value generated by said differentiating circuit is detected as a center; and sweep center wavelength setting means receiving said first-order differentiation value from said differentiation circuit and for setting a transmission center wavelength of said first branched optical signal obtained when the first-order value generated by said differentiating circuit becomes "0" to a center wavelength of a band subjected to a next sweep by said narrow-band sweep means while a transmission center wavelength is repeatedly swept by said narrow-band sweep means.

Claim 18

A light amplification device, comprising: a light amplifier for amplifying an inputted optical signal; a bandpass filter for transmitting an optical signal having a wavelength within a predetermined transmission band of optical signals output from said light amplifier; an optical signal branching unit for branching the optical signal from said bandpass filter to first and second branched optical signals; controllable transmission center wavelength sweep means included at least partially within said bandpass filter for sweeping a transmission center wavelength of said bandpass filter in a predetermined band at a predetermined speed; a photoelectric converter for converting an intensity of said second branched optical signal transmitted through said bandpass filter into an electrical signal; a differentiating circuit for performing first-order differentiation and second-order differentiation on the electrical signal converted by said photoelectric converter using time as a variable, and for generating first-order and second order differentiation values representative of said first and second-order differentiations, respectively; narrow-band sweep means for receiving said second-order differentiation value from said differentiation circuit and for repeatedly sweeping a transmission center wavelength of said first branched optical signal at a predetermined speed in a band of several fractions of a nm using a transmission center wavelength of said first branched optical signal obtained when a negative peak value of the second-order value generated by said differentiating circuit is detected as a center; and sweep center wavelength setting means receiving said first-order differentiation value from said differentiation circuit and for setting a transmission center wavelength of said first branched optical signal obtained when the first-order value generated by said differentiating circuit becomes "0" to a center wavelength of a band subjected to a next sweep by said narrow-band sweep means while a transmission center wavelength is repeatedly swept by said narrow-band sweep means.