Prefaceforthesecondedition Chaos research in laser physics, especially in semiconductor lasers, has - veloped further even after completion of the ?rst edition of this book in the late summer of 2004, and it is still growing rapidly. For example, various forms of chaotic dynamics have been applied in newly developed semic- ductor lasers,such as in vertical-cavitysurface-emitting semiconductor lasers and broad-area semiconductor lasers. Chaotic dynamics plays an important role in these new lasers, even for their solitary oscillations, and control of the dynamics is currently an important issue for practical applications. - other signi?cant advance has been made in the area of chaotic optical secure communications. Chaotic secure communications using existing public opt- al communications links have been tested, and successful results have been obtained. In this second edition, I have ?lled in the gaps in the explanation of chaotic laser dynamics in the previous edition, and I have alsoadded s- eral important topics that have been developed recently. In particular, a new chapter on laser stabilizations has been added, and a number of misprints in the ?rst edition have been corrected. I believe this book will be of interest not only to researchers in the ?eld of laser chaos, but also to those working in nonlinear science and technology. Hamamatsu, Spring 2007 Junji Ohtsubo Preface Theaimofthisbookisthedescriptionofthestateoftheartofchaosresearch in semiconductor lasers and their applications, and the future perspective of this ?eld.