| 摘要 |
The rugate filter comprises a glass film which is deposited on one or both end facets of a diode laser. The glass film has a continuously varying refractive index with thickness, usually in the form of a sine wave or a "windowed" sine wave. Such a film may be deposited by ion-assisted co-deposition techniques in which the concentration of the higher refractive index material is periodically varied according to the period required to produce the desired filter. The glass of which the rugate filter is formed has an average refractive index which does not vary with temperature by more than 10-6/ DEG C. By reflecting light at the peak wavelength back into the laser, the laser is caused to emit at the desired wavelength. Since the rugate filter selectively reflects light within a narrow band of the desired wavelength, the laser emits light within a narrow peak on the order of 10 ANGSTROM or less.
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