Wavelength tunable laser

Abstract

This invention provides a tunable laser capable of suppressing mode hopping. [Solution] A tunable laser comprising: gain regions and wavelength control regions arranged alternately along the direction of light propagation; diffraction gratings arranged corresponding to the gain regions and the wavelength control regions, respectively; and a plurality of regions without diffraction gratings located at the boundary between the gain regions and the wavelength control regions, at least one of the ends of the gain regions and the ends of the wavelength control regions, wherein the length of the regions without diffraction gratings is 5% or more and 30% or less of the length of the gain region or the wavelength control region to which it belongs.

Claims

1. Gain regions and wavelength control regions are arranged alternately along the direction of light propagation, A diffraction grating arranged in accordance with the gain region and the wavelength control region, The boundary between the gain region and the wavelength control region includes a region located at least one of the ends of the gain region and the ends of the wavelength control region, which does not have a plurality of diffraction gratings. A tunable laser in which the length of the region without a diffraction grating is 5% or more and 30% or less of the length of the gain region or the wavelength control region to which it belongs.

2. The tunable laser according to claim 1, wherein the number of regions without diffraction gratings is 70% or more of the total number of boundaries formed by the gain region and the wavelength control region.

3. The tunable laser according to claim 1, wherein the region without a diffraction grating is also located at the outermost edge of the gain region or the wavelength control region.

4. The tunable laser according to claim 1, wherein the length of the region without a diffraction grating is 10% or more and 25% or less of the length of the gain region or the wavelength control region to which it belongs.

5. The tunable laser according to claim 1, wherein the length of the region without a diffraction grating is 15% or more and 20% or less of the length of the gain region or the wavelength control region to which it belongs.

6. A tunable laser according to any one of claims 1 to 5, further comprising an optical modulator that optically couples with the gain region and the wavelength control region.

7. The tunable laser according to claim 6, wherein a variable optical attenuator is arranged between the gain region and the wavelength control region and the optical modulator.

8. The tunable laser according to claim 6 or claim 7, wherein a semiconductor optical amplifier is provided at the output of the optical modulator.

9. The tunable laser according to claim 1, wherein the refractive index of the wavelength control region is controlled by current injection.

10. The tunable laser according to claim 1, wherein the refractive index of the wavelength control region is controlled by a heater.

11. The tunable laser according to claim 1, wherein the region without the diffraction grating is located at either end of the gain region or the wavelength control region.

12. The tunable laser according to claim 1, wherein the region without the diffraction grating is located at both ends of the gain region and the wavelength control region.

13. The tunable laser according to claim 1, wherein the region without the diffraction grating is located only at one end of either the gain region or the wavelength control region.

Images