Gain controllable optical amplifier and applications thereof

Claim 2

An optical amplifier for amplifying a power of an input signal, comprising: (A) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (B) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (C) a compensation-signal source coupled with the output side of the rare earth doped fiber having a compensation-signal propagating contra-directionally with respect to the input signal for compensating the power of the input signal; (D) an optical receiver, coupled with the input side of the rare earth doped fiber, for measuring power of a propagating amplified-spontaneous-emission (ASE) generated by the pump-source in the rare earth doped fiber; and, (E) a compensation-signal controller for controlling power of the compensation-signal source in response to the measured power of the ASE.

Claim 3

The optical amplifier according to claim 1, wherein the compensation-signal source is controlled so that total power of the input signal and the compensation-signal is constant.

Claim 4

The optical amplifier according to claim 1, wherein a wavelength of the input signal and a wavelength of the compensation-signal are nearly equal.

Claim 5

The optical amplifier according to claim 1, wherein a wavelength of the input signal and a wavelength of the pump-source are nearly equal.

Claim 6

The optical amplifier according to claim 1, wherein the compensation-signal source is pulse width modulated.

Claim 7

The optical amplifier according to claim 1, further comprising an optical isolator at the input side of the rare earth doped fiber for isolating transmission of the compensation-signal.

Claim 8

The optical amplifier according to claim 1, further comprising a wavelength-selective reflector coupled with the input side of the rare earth doped fiber for reflecting the compensation-signal.

Claim 9

The optical amplifier according to claim 1, further comprising: a first wavelength detector for detecting a wavelength of the input signal; a second wavelength detector for detecting a wavelength of the compensation-signal; and wavelength controller, receiving the detected wavelengths from said first and second wavelength detectors, for controlling the wavelength of the compensation-signal so that it is different from the wavelength of the input signal.

Claim 10

An optical amplifier according to claim 1, further comprising: a modulator for modulating the compensation-signal source to produce a monitor signal in response to the output of the pump-source, wherein said compensation signal transmits said monitor signal to a previous optical element connected to said input side of said rare earth doped fiber.

Claim 11

An optical amplifier according to claim 1, further comprising: a modulator for modulating the compensation-signal source to produce a monitor signal in response to the measured power of the ASE, wherein said compensation-signal transmits said monitor signal to a previous optical element connected to said input side of said rare earth doped fiber.

Claim 12

An optical amplifier for amplifying a power of an input signal, comprising: (A) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (B) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (C) a compensation-signal source coupled with the input side of the rare earth doped fiber having a compensation-signal propagating co-directionally with respect to the input signal for compensating the power of the input signal; (D) an optical receiver, coupled with the input side of the rare earth doped fiber, for measuring power of a propagating amplified-spontaneous-emission (ASE) generated by the pump-source in the rare earth doped fiber; (E) a compensation-signal controller for controlling power of the compensation-signal source in response to the measured power of the ASE; (F) a modulator for modulating the compensation-signal source to produce a monitor signal, wherein said compensation signal transmits said monitor signal to a previous optical element connected to said input side of said rare earth doped fiber.

Claim 13

An optical amplifier for amplifying a power of an input signal, comprising: (A) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (B) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (C) a compensation-signal source coupled with the input side of the rare earth doped fiber having a compensation-signal propagating co-directionally with respect to the input signal for compensating the power of the input signal; (D) an optical receiver, coupled with the input side of the rare earth doped fiber, for measuring power of a propagating amplified-spontaneous-emission (ASE) generated by the pump-source in the rare earth doped fiber; (E) a compensation-signal controller for controlling power of the compensation-signal source in response to the measured power of the ASE; (F) a modulator for modulating the compensation-signal source to produce a monitor signal, wherein said compensation signal transmits said monitor signal to a previous optical element connected to said input side of said rare earth doped fiber.

Claim 14

The optical amplifier according to claim 11, wherein said modulator produces the monitor signal in response to the power of the ASE.

Claim 15

The optical amplifier according to claim 9, wherein a wavelength of the compensation-signal is different from a wavelength of the input signal.

Claim 16

An optical amplifier for amplifying a power of an input signal, comprising: (A) a rare earth doped fiber having an input side and output side, for amplifying the power of the input signal; (B) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (C) an optical receiver, coupled to the output side of the rare earth doped fiber, for measuring power of the input signal; (D) a filter coupled with the input side of the rare earth doped fiber for filtering a power of a propagating amplified-spontaneous-emission (ASE) generated by the pump-source; and (E) an attenuation controller for controlling an attenuation of the filtered power of the ASE in response to the measured power of the input signal, and for outputting the filtered power of the ASE after the attenuation to the output side of the rare earth doped fiber contra-directionally with respect to the output signal.

Claim 17

An optical amplifier for amplifying a power of an input signal, comprising: (A) a rare earth doped fiber having an input side and output side, for amplifying the power of the input signal; (B) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (C) an optical receiver, coupled to the output side of the rare earth doped fiber, for measuring power of the input signal; (D) a filter coupled with the input side of the rare earth doped fiber for filtering a power of a propagating amplified-spontaneous-emission (ASE) generated by the pump-source; and (E) an attenuation controller for controlling an attenuation of the filtered power of the ASE in response to the measured power of the input signal, and for outputting the filtered power of the ASE after the attenuation to the output side of the rare earth doped fiber contra-directionally with respect to the output signal.

Claim 18

The optical amplifier according to claim 14, wherein a wavelength of the ASE is different from a wavelength of the input signal.

Claim 19

An optical amplifier for amplifying a power of an input signal, comprising: (A) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (B) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (C) a wavelength-selective reflector, coupled to the input side of the rare earth doped fiber, for reflecting a light having a specific wavelength as a compensation signal, and (D) a filter coupled to the input side of the rare earth doped fiber for selecting the compensation signal.

Claim 20

An optical amplifier for amplifying a power of an input signal, comprising: (A) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (B) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (C) a wavelength-selective reflector, coupled to the input side of the rare earth doped fiber, for reflecting a light having a specific wavelength as a compensation signal, and (D) a filter coupled to the input side of the rare earth doped fiber for selecting the compensation signal.

Claim 21

A distribution system comprising: (A) a first optical coupler for mixing original input signals, and for distributing the original input signals after mixing as a distributed input signal; (B) an optical amplifier connected to the first optical coupler for amplifying power of the distributed input signal, and for outputting the amplified input signal as an output signal, wherein the optical amplifier includes: (i) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (ii) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (iii) a compensation-signal source coupled with the output side of the rare earth doped fiber having a compensation-signal propagating contra-directionally with respect to the input signal for compensating the power of the input signal; (iv) an optical receiver, coupled with the input side of the rare earth doped fiber, for measuring power of a propagating amplified-spontaneous-emission (ASE) generated by the pump-source in the rare earth doped fiber; and (v) a compensation-signal controller for controlling power of the compensation-signal source in response to the measured power of the ASE; and (C) a second optical coupler coupled to the optical amplifier for mixing and distributing the output signal.

Claim 22

A distribution system comprising: (A) a first optical coupler for mixing original input signals, and for distributing the original input signals after mixing as a distributed input signal; (B) an optical amplifier connected to the first optical coupler for amplifying power of the distributed input signal, and for outputting the amplified input signal as an output signal, wherein the optical amplifier includes: (i) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (ii) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (iii) a compensation-signal source coupled with the output side of the rare earth doped fiber having a compensation-signal propagating contra-directionally with respect to the input signal for compensating the power of the input signal; (iv) an optical receiver, coupled with the input side of the rare earth doped fiber, for measuring power of a propagating amplified-spontaneous-emission (ASE) generated by the pump-source in the rare earth doped fiber; and (v) a compensation-signal controller for controlling power of the compensation-signal source in response to the measured power of the ASE; and (C) a second optical coupler coupled to the optical amplifier for mixing and distributing the output signal.

Claim 23

A local area network system comprising: (A) a first optical coupler for mixing original input signals from previous local area networks, and for distributing the mixed input signals; (B) an optical amplifier connected to the first optical coupler for amplifying a power of the distributed input signals, and for outputting the amplified input signals as an output signal, wherein the optical amplifier includes: (i) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (ii) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (iii) a compensation-signal source coupled with the output side of the rare doped fiber having a compensation-signal propagating contra-directionally with respect to the input signal for compensating the power of the input signal; (iv) an optical receiver, coupled with the input side of the rare earth doped fiber, for measuring power of a propagating amplified-spontaneous-emission (ASE) generated by the pump-source in the rare earth doped fiber; and (v) a compensation-signal controller for controlling power of the compensation-signal source in response to the measured power of the ASE; and (C) a second optical coupler for mixing the output signals of the optical amplifier, and for distributing each of the mixed output signals to a next local area network.

Claim 24

A local area network system comprising: (A) a first optical coupler for mixing original input signals from previous local area networks, and for distributing the mixed input signals; (B) an optical amplifier connected to the first optical coupler for amplifying a power of the distributed input signals, and for outputting the amplified input signals as an output signal, wherein the optical amplifier includes: (i) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (ii) a pump-source coupled to said output side of said rare earth doped fiber having an output propagating contra-directionally with respect to the input signal; (iii) a compensation-signal source coupled with the output side of the rare doped fiber having a compensation-signal propagating contra-directionally with respect to the input signal for compensating the power of the input signal; (iv) an optical receiver, coupled with the input side of the rare earth doped fiber, for measuring power of a propagating amplified-spontaneous-emission (ASE) generated by the pump-source in the rare earth doped fiber; and (v) a compensation-signal controller for controlling power of the compensation-signal source in response to the measured power of the ASE; and (C) a second optical coupler for mixing the output signals of the optical amplifier, and for distributing each of the mixed output signals to a next local area network.

Claim 27

The method of claim 19, wherein the computation step includes using a table between the power of ASE and the power of the compensation-signal.

Claim 28

The method of claim 19, wherein the steps are performed periodically.

Claim 29

The method of claim 19 further including the steps of: detecting a wavelength of the input signal, and controlling a wavelength of the compensation-signal so that it is different from that of the input signal.

Claim 32

The method of claim 23, wherein the steps (A) to (E) are performed periodically.

Claim 33

The optical amplifier according to claim 11, wherein said modulator produces the monitor signal in response to the power of the pump-source.

Claim 34

The optical amplifier according to claim 11, wherein a wavelength of the compensation-signal is different from a wavelength of the input signal.

Claim 35

An optical amplifier for amplifying an input signal comprising: (A) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (B) pump-source means for generating an amplified-spontaneous-emission (ASE) contra-directionally with respect to the input signal; and (C) compensation-signal means coupled to the rare earth doped fiber for compensating power of the input signal in response to power of the ASE, wherein said compensation-signal means includes means for measuring power of said ASE.

Claim 36

An optical amplifier for amplifying an input signal comprising: (A) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (B) pump-source means for generating an amplified-spontaneous-emission (ASE) contra-directionally with respect to the input signal; and (C) compensation-signal means coupled to the rare earth doped fiber for compensating power of the input signal in response to power of the ASE, wherein said compensation-signal means includes means for measuring power of said ASE.

Claim 37

The optical amplifier of claim 27, wherein said measuring means includes an optical receiver.

Claim 38

The optical amplifier of claim 27, wherein said compensation-signal means includes a filter for filtering means for controlling the wavelength of said compensation-signal when the wavelength of said input signal is substantially equal to the wavelength of said compensation-signal.

Claim 39

The optical amplifier of claim 27, wherein said compensation-signal means includes a compensation-signal source connected to the output side of the rare earth doped fiber for propagating a compensation-signal contra-directionally with respect to the input signal.

Claim 40

The optical amplifier of claim 30, further comprising a controller for controlling power of said compensation-signal source.

Claim 41

The optical amplifier of claim 31, wherein said controller includes pulse width modulated control.

Claim 42

The optical amplifier of claim 30, wherein said compensation-signal has a wavelength different than said input signal.

Claim 43

The optical amplifier of claim 33, further comprising: means for detecting the wavelength of said input signal, means for detecting the wavelength of said compensation-signal, and means for controlling the wavelength of said compensation-signal when the wavelength of said input signal is substantially equal to the wavelength of said compensation-signal.

Claim 44

The optical amplifier of claim 27, further comprising reflection means coupled to the input of said rare earth doped fiber for reflective selected wavelengths co-directionally with respect to said input signal.

Claim 45

The optical amplifier of claim 35, wherein said reflection means reflects wavelengths corresponding to said compensation-signal.

Claim 46

The optical amplifier of claim 27, further comprising modulation means for modulating said compensation-signal means to produce a monitor signal.

Claim 47

The optical amplifier of claim 37, wherein said modulation means modulates said compensation-signal means based upon power of said pump-source means.

Claim 48

The optical amplifier of claim 37, wherein said modulation means modulates said compensation-signal means based upon power of said ASE.

Claim 49

The optical amplifier of claim 37, wherein said compensation-signal means propagates a compensation-signal through said rare earth doped fiber contra-directionally with respect to the input signal.

Claim 50

An optical amplifier for amplifying an input signal comprising: (A) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (B) pump-source means for generating an amplified-spontaneous-emission (ASE) Contra-directionally with respect to the input signal; and (C) compensation-signal means coupled to the rare earth doped fiber for compensating power of the input signal in response to power of the ASE, wherein said compensation means includes: (D) filter means coupled to the input side of the rare earth doped fiber for filtering said ASE; and reflecting means for reflecting said filtered ASE through rare earth doped fiber co-directionally with respect to said input signal.

Claim 51

An optical amplifier for amplifying an input signal comprising: (A) a rare earth doped fiber having an input side and an output side, for amplifying the power of the input signal; (B) pump-source means for generating an amplified-spontaneous-emission (ASE) Contra-directionally with respect to the input signal; and (C) compensation-signal means coupled to the rare earth doped fiber for compensating power of the input signal in response to power of the ASE, wherein said compensation means includes: (D) filter means coupled to the input side of the rare earth doped fiber for filtering said ASE; and reflecting means for reflecting said filtered ASE through rare earth doped fiber co-directionally with respect to said input signal.

Claim 52

The optical amplifier of claim 41, wherein said reflecting means includes a wavelength-selective reflector.

Claim 55

The method of claim 43, wherein said controlling step includes the step of propagating a compensation-signal contra-directionally with respect to the input signal.

Claim 56

The method of claim 44, wherein said compensation-signal has a wavelength different than said input signal.

Claim 57

The method of claim 45, further comprising the steps of: detecting the wavelength of said input signal, detecting the wavelength of said compensation-signal, and controlling the wavelength of said compensation-signal when the wavelength of said input signal is substantially equal to the wavelength of said compensation-signal.

Claim 58

The method of claim 44, wherein said controlling step includes reflecting said compensation-signal co-directionally with respect to said input signal.