| The quantum noise limits of semiconductor lasers have attracted a lot of attention because of their impact on the numerous applications where semiconductor lasers have advantages over other kinds of lasers. The FM noise is directly related with the spectral purity and can be dramatically reduced by introducing dispersive optical feedback. By refining this scheme a record low FM noise level was achieved, leading to an ultra-narrow linewidth of 44Hz.;Recently the possibility of generating amplitude-squeezed light with pump-suppressed room temperature semiconductor lasers has been studied extensively, and it has been found that dispersive optical feedback can also enhance the squeezing. The mechanisms behind this phenomenon are investigated using quantum Langevin equations and the various affecting factors are explored. By extending the single-mode theory to multi-mode theory and including nonlinear gain and loss, a very good fit with the experiment data is obtained, indicating that in reality this model is more accurate. The influence on the squeezing is discussed. The advantage of using photonic band gap defect lasers has also been studied. |
