| 摘要 |
<p>According to this invention, a 'low field enhancement' (LFR) semiconductor saturable absorber device design is proposed. In this design, the structure is changed with respect to the prior art such that it no longer satisfies the anti-resonant condition but a resonant condition. Consequently the field strength is substantially higher in the spacer layer, resulting in a smaller saturation fluence and in a higher modulation depth. However, the field in the spacer layer is still lower than the free space field or only moderately enhanced compared to the latter. According to one embodiment, the absorber device is a saturably absorbing semiconductor mirror device. In contrast with mirror devices according to the state of the art, a structure comprising the absorber and being placed on top of a Bragg reflector is provided which essentially fulfills a resonance condition, i.e. a standing electromagnetic wave is present in the structure. In other words, the design is such that the field intensity reaches a local maximum in the vicinity of the device surface.</p> |
