Raman amplifier system

1. A Raman amplifier system comprising:

an optical wave guide having an isotopically purified crystalline material, for guiding an optical signal having a first wavelength, the crystalline material having a Raman wavelength shift,

a pump configured to pump light into the optical wave guide, the pump light having a second wavelength being substantially equal to the first wavelength minus the Raman wavelength shift.

2. The Raman amplifier system of claim 1 , the crystalline material being a semiconductor material, preferably a semiconductor material from group IV, III–V or II–VI, such as silicon, indium-phosphite, gallium-arsenite or silicon-germanium.

3. The Raman amplifier system of claim 1 , wherein said crystalline material is a semiconductor.

4. The Raman amplifier system of claim 1 , the optical waveguide being provided by a membrane of a semiconductor layer.

5. The Raman amplifier system of claim 1 , the optical waveguide being provided by a defect waveguide in a photonic crystal.

6. The Raman amplifier system of claim 1 , further comprising a plurality of the pumps for separate Raman amplification of a plurality of optical signals having a plurality of wavelengths.

7. A method of generating a Raman gain, the method comprising the steps of:

providing an optical wave guide an isotopically purified crystalline material,

propagating an optical signal through the optical wave guide, the optical signal having a first wavelength,

introducing of pump light into the optical wave guide, the pump light having a second wavelength being substantially equal to the first wavelength minus the Raman wavelength shift.

8. The method of claim 7 , further comprising:

propagating at least a second optical signal having a third wavelength through the optical wave guide,

introducing pump light into the optical wave guide, the pump light having a fourth wavelength being substantially equal to the third wavelength minus the Raman wavelength shift.

9. The Raman amplifier system of claim 1 , wherein said rib-like structure comprises a layer of said crystalline material having a first thickness on either side of a rib section of greater thickness than said first thickness.

10. The Raman amplifier system of claim 1 , wherein said crystalline material comprises a rib-like geometry of crystalline material on an insulator layer.

11. The Raman amplifier system of claim 3 , wherein said crystalline material comprises silicon.

12. The method of claim 7 , wherein said crystalline material comprises silicon.