Tunable wavelength light source incorporated optical filter using interferometer into external cavity
US5444724A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 25, 1994 |
| Grant date | Aug 22, 1995 |
| Priority date | — |
| Expiry date | Aug 25, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/0687
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In an external-cavity tunable wavelength light source using a semiconductor laser (LD), when an interferometer serving as an optical filter is constituted by part of an external cavity, an external-cavity longitudinal mode can be selected with good reproducibility, and a side mode suppression ratio can be increased. A light beam emitted from an AR-coated facet of an LD is converted into a collimated beam by a lens, and the collimated beam is incident on a Mach-Zehnder (MZ) interferometer serving as an optical filter. An interference light beam emerges from the MZ interferometer toward a diffraction grating. Only a light component having a specific wavelength and selected by spectrally dispersing the interference light beam reversely travels in the same optical path as that of the interference light beam and is returned to the LD. In this manner, a cavity is formed between the LD and the diffraction grating, and a laser beam having a wavelength determined by three relationships between an external-cavity longitudinal mode, a cavity loss caused by the diffraction grating, and the output characteristics of an interference light beam from the MZ interferometer is oscillated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.