Optical amplifier and an optical amplification method

• US 8,576,480 B2
• Filed: 06/07/2012
• Issued: 11/05/2013
• Est. Priority Date: 06/08/2011
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Yoshida, Hideshi
• Primary Examiner(s): Hellner, Mark
• Assistant Examiner(s): Diacou, Ari M
• Application Number:
  US13/491,059
• Publication Number:
  US 20120314278A1
• Time in Patent Office: 516 Days
• Field of Search: 359/341.43, 398/34, 398/86, 398/177, 398/180, 385/25, 385/26, 385/36
• US Class Current: 359/341.43
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02B 6/4286 Optical modules with optical power monitoring
• CPC Class Codes: H01S 3/0014 Monitoring arrangements not otherwise provided for photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/10015 by monitoring or controlling, e.g. attenuating, the input signal
• CPC Class Codes: H01S 3/13013 by controlling the optical pumping
• CPC Class Codes: H01S 3/1305 Feedback control systems
• CPC Class Codes: H01S 3/1306 Stabilisation of the amplitude
• CPC Class Codes: H01S 3/1312 by controlling the optical pumping
• CPC Class Codes: H01S 3/1608 erbium
• CPC Class Codes: H04B 10/07957 Monitoring or measuring wavelength
• CPC Class Codes: H04B 10/296 Transient power control, e.g. due to channel add/drop or rapid fluctuations in the input power

Abstract

An optical amplifier using the evanescent light to control the optical output level is provided. The optical amplifier includes: a waveguide path transmitting an optical signal; an optical amplification unit formed on the waveguide path and amplifying the optical signal by an excitation light; an irradiation unit irradiating the excitation light to the optical amplification unit; an optical detection unit generating an electric signal which corresponds to a detected light; a branching unit branching an evanescent light being the optical signal outputted from the optical amplification unit and leaked outside the waveguide path, and focusing the evanescent light on the optical detection unit; a wavelength detection unit detecting a wavelength multiplicity of the optical signal based on the detected evanescent light; and a light amount adjustment unit adjusting a light amount of the excitation light irradiated by the irradiation unit based on the wavelength multiplicity.

Claims

1. An optical amplifier comprising:

a waveguide path configured to transmit an optical signal;

an optical amplification unit formed on the waveguide path and configured to amplify the optical signal by an excitation light;

an irradiation unit configured to irradiate the excitation light to the optical amplification unit;

an optical detection unit configured to detect a light and generate an electric signal which corresponds to the detected light;

a branching unit configured to branch an evanescent light being the optical signal outputted from the optical amplification unit to the waveguide path and leaked outside the waveguide path, and focus the evanescent light on the optical detection unit;

a wavelength detection unit configured to detect a wavelength multiplicity of the optical signal based on the evanescent light detected by the optical detection unit; and

a light amount adjustment unit configured to adjust a light amount of the excitation light irradiated by the irradiation unit based on the wavelength multiplicity.

2. The optical amplifier according to claim 1, further comprising:

a driving unit configured to move the branching unit along the waveguide path.

3. The optical amplifier according to claim 1, wherein the optical amplification unit is an erbium doped fiber,

wherein the irradiation unit is a laser diode, and

the optical detection unit is a photodiode.

4. The optical amplifier according to claim 1, wherein the branching unit is a prism.

5. The optical amplifier according to claim 1, wherein the branching unit is a diffraction grating.

6. An optical amplifying method comprising:

amplifying an optical signal which transmits through a waveguide path by an excitation light by an optical amplification unit formed on the waveguide path;

irradiating the excitation light to the optical amplification unit;

detecting a light and generate an electric signal which corresponds to the detected light by an optical detection unit;

branching an evanescent light being the optical signal outputted from the optical amplification unit to the waveguide path and leaked outside the waveguide path;

focusing the evanescent light on the optical detection unit;

detecting a wavelength multiplicity of the optical signal based on the evanescent light detected by the optical detection unit; and

adjusting a light amount of the excitation light irradiated by the irradiation unit based on the wavelength multiplicity.

7. The optical amplifying method according to claim 6, further comprising:

moving the branching unit along the waveguide path.