| 摘要 |
<p>A tunable Raman (40) laser and amplifier include a pair of tunable optical units (42, 44) optically connected by a length of optical fiber (46) having an associated Raman gain. The tunable optical units (42, 44) tune respective optical waveguides (50, 60), each of which includes an inner core (56) disposed within an outer cladding (58). A plurality of Bragg gratings (51-54, 61-64) is written in each core (56) of the waveguides (50, 60). The reflexion wavelengths of each Bragg grating (51-54) of the input waveguide (50) is the same as the reflection wavelength of a matched grating of the output waveguide (60), to thereby form a plurality of cascaded resonance cavities. Each resonance cavity has a reflecting wavelength equal to the center wavelength of successive Stokes orders associated with optical fiber. The Bragg gratings (51-54, 61-64) of each waveguide (50, 60) are written into a corresponding stepped region ground into the outer cladding (58) of the waveguides (50, 60). The tuning (e.g., compression) of the waveguides proportionally changes the reflexion wavelengths of the gratins, and thereby proportionally changes the center wavelength of each resonance cavity. This method of proportionally tuning each matched pair of Bragg gratings enables the Raman laser to be tunable over an extended wavelength range.</p> |
