Tunable laser and tuning method using the same

#Field of the Invention

#The invention relates to a tunable laser and a tuning method using the same.

#Description of the Related Art

#The invention is described hereinbelow with reference to the accompanying drawings, in which:

#FIG. 1 is a schematic drawing of the tuning principle of tunable semiconductor lasers;

#FIG. 2 is a schematic drawing of Vernier effect (λ0);

#In the drawings, the following reference numbers are used: 1. Gain section; 2. Common phase section; 3. Multi-channel splitter section; 4. Multi-channel reflection section; 5. Arm phase section; 6. High-reflection coating film; 7. Output facet of the laser; 8. 1×2 MMI; 9. S bends; 10. Electrode contact layer; 11. Cladding layer; 12. Upper optical confinement layer; 13. Active layer; 14. Lower optical confinement layer; 15. Optical waveguide layer; and 16. Electrode.

#For further illustrating the invention, examples detailing a tunable laser and a tuning method using the same are described below. It should be noted that the following examples are intended to describe and not to limit the invention.

#FIG. 4 is a schematic drawing of an MCI laser. The MCI laser comprises four sections: a gain section 1, a common phase section 2, a multi-channel splitter section 3, and a multi-channel reflection section 4. The common phase section 2 is between the gain section 1 and the multi-channel splitter section 3. The multi-channel splitter section 3 is between the common phase section 2 and the multi-channel reflection section 4. The gain section 1 is used to provide optical gain for lasing. The common phase section 2 is used to shift the cavity longitudinal mode. The multi-channel splitter section 3 is optionally realized by multimode interferometers (MMI), Y-branches, star coupler. The multi-channel splitter section 3 is used to split the input optical field into multiple outputs. The multi-channel reflection section 4 is composed of multiple arms with unequal lengths and there is an independent arm phase section 5 on each arm. Besides, the ends of the multiple arms are coated with reflection films 6. The arm phase sections are used to adjust the phases of each arm. The multi-channel reflection section 4 is used to achieve mode selection and provide optical feedback for the laser to work. The optical output facet 7 of the MCI laser is a facet of the gain section 1 away from the multi-channel splitter section.