Semiconductor laser beam combining

In this chapter, we will review recent advances and trends in phase locking of broad-area laser diode arrays. In particular, we will concentrate on coherent phase locking of high-power, broad-area diode arrays in a passive external cavity. We will present a newly designed external cavity called the V-shape external Talbot cavity. The V-shape external cavity is capable of selecting single transverse mode operation of individual laser diodes on an array and providing optical coupling among laser diodes. The high visibility far-field interference pattern confirms that phase locking is achieved among laser diodes on an array. Two experimental schematic designs of the V-shape external Talbot cavity are explored. One is the V-shape external Talbot cavity, and the other is the closed V-shape external Talbot cavity. The differences in external cavity design and performance will be discussed.