| 摘要 |
A frequency tuneable laser device comprises a cavity mode selector (10) and a cavity tuning arrangement(22, 24). The cavity mode selector (10) has a frequency response with a selection feature that is alignable in frequency with a selected cavity mode of the laser device. The cavity tuning arrangement (22, 24) comprises a plurality of reflective elements arranged in optical series, and is used to adjust the effective optical path length of the laser cavity to move the cavity modes in frequency. The laser device further comprises means (30, 40) for making the cavity mode selector (10) and the cavity tuning arrangement (22, 24) perform a simultaneous coordinated movement such that respective frequencies of the selection feature and the selected cavity mode vary with substantially the same dependence on a parameter characterising the simultaneous coordinated movement. For example, a periscope (22, 24) with a co- rotating etalon (10) can be used to provide mode hop free tuning of the laser device, particularly where the periscope (22, 24) is configured to give a predominantly cosine tuning response. |
