Dynamic spectral shaping for fiber-optic application

• US 6,826,330 B1
• Filed: 04/14/2000
• Issued: 11/30/2004
• Est. Priority Date: 08/11/1999
• Status: Expired due to Term

• Current Assignee: NeoPhotonics Corporation (Lumentum Holdings Inc.)
• Original Assignee: Lightconnect, Inc. (Lumentum Holdings Inc.)
• Inventors: Bloom, David M., Godil, Asif A.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Kianni, Kevin
• Application Number:
  US09/549,781
• Time in Patent Office: 1,691 Days
• Field of Search: 385/33, 385/37, 385/10, 385/31, 385/129
• US Class Current: 385/37
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955
• CPC Class Codes: G02B 6/266 the optical element being an attenuator
• CPC Class Codes: G02B 6/2793 Controlling polarisation dependent loss, e.g. polarisation insensitivity, reducing the change in polarisation degree of the output light even if the input polarisation state fluctuates
• CPC Class Codes: G02B 6/3516 the reflective optical element moving along the beam path, e.g. controllable diffractive effects using multiple micromirrors within the beam
• CPC Class Codes: G02B 6/3592 Means for removing polarization dependence of the switching means, i.e. polarization insensitive switching light guides coupling with polarization selective and adjusting means G02B6/27
• CPC Class Codes: H01S 5/005 Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence

Abstract

The present invention is directed towards dynamic spectral shaping. Using a grating, the spectral band is spread across a MEMS or other suitable device array. The device may be the deformable grating modulator invented by Bloom et. al. (U.S. Pat. No. 5,311,360) or other suitable device. The invention also includes the coupling in and out of the fiber and may use polarization optics to ensure the grating is used in only one polarization where the diffraction efficiency is higher.

Claims

1. A dynamic spectral shaping device with a controllable transmission as a function of wavelength, comprising:

a fiber optic input port providing an input beam;

a wavelength dispersive element coupled through free space to the input port, the wavelength dispersive element spreading the input beam in at least one dimension as a function of wavelength and generating a dispersed beam;

a controllable grating reflecting the dispersed beam to the wavelength dispersive element and generating a recombined beam, the controllable grating providing a controllable reflectivity as a function of wavelength; and

a fiber optic output port positioned to receive the recombined beam.

2. The device of claim 1, wherein the controllable grating is an array with a diffraction efficiency that is controlled as a function of position on the array.

3. The device of claim 1, wherein the controllable grating is an array of ribbons.

4. The device of claim 1, wherein the controllable grating is a micromachined grating device.

5. The device of claim 1, further comprising:

a first lens positioned between the fiber optic input port and the wavelength dispersive element.

6. The device of claim 1, further comprising:

a second lens positioned between the wavelength dispersive element and the controllable grating.

7. The device of claim 1, further comprising:

a birefringent plate positioned between the fiber optic input port and the wavelength dispersive element.

8. The device of claim 1, further comprising:

a half-wave plate positioned between the fiber optic input port and the wavelength dispersive element.

9. The device of claim 1, further comprising:

a quarter-wave plate positioned between the wavelength dispersive element and the controllable grating.

10. The device of claim 1, further comprising:

a second birefringent plate positioned between the wavelength dispersive element and the fiber optic output port.

11. An optical system, comprising:

an EDFA system including at least one amplifier stage;

a spectral shaping device coupled to the EDFA system, the spectral shaping device including;

a fiber optic input port providing an input beam;

a wavelength dispersive element coupled through free space to the input port, the wavelength dispersive element spreading the input beam in at least one dimension as a function of wavelength and generating a dispersed beam;

a controllable grating reflecting the dispersed beam to the wavelength dispersive element and generating a recombined beam, the controllable grating providing a controllable reflectivity as a function of wavelength;

a fiber optic output port positioned to receive the recombined beam; and

wherein the optical system provides a desired controllable wavelength flatness.

12. The system of claim 11, wherein the at least one amplifier stage of the EDFA system is coupled to the fiber optic output port.

13. The system of claim 11, wherein the at least one amplifier stage of the EDFA system is coupled to the fiber optic input port.

14. The system of claim 11, wherein at least a portion of the spectral shaping device is incorporated in the EDFA system.

15. An optical system, comprising:

a fiber optic input port providing an input beam;

a wavelength dispersive element coupled through free space to the input port, the wavelength dispersive element spreading the input beam in at least one dimension as a function of wavelength and generating a dispersed beam;

a controllable grating reflecting the dispersed beam to the wavelength dispersive element and generating a recombined beam, the controllable grating providing a controllable reflectivity as a function of wavelength;

a fiber optic output port positioned to receive the recombined beam; and

an EDFA coupled to the fiber optic input port, wherein the optical system provides a desired controllable wavelength flatness.