Research On The Characteristics Of A Laser Diode Array Phase-Locked In An External Cavity

Laser Diode Array (LDA) is attractive for its high output power and compactness. However the relatively poor spatial property of LDA's output limits its applications in many fields. The method of external phase-locking via an external mirror can greatly improve the output property of the LDA. Since it is suitable for high power, wide aperture LDA, the application of the external phase-locking method is promising. Many experiments had been carried out to investigate the output characteristics of external phase-locked LDA, but the relevant theoretical works are still rare to see. And the parameters influencing the working property of the phase-locking system still require more discussions. In this thesis, we have established a set of self-consistent external coupling theory based on the method of external phase-locking via a plan mirror, and investigated some important factors that influence the phase-locking effects.In the case of external coupling, because of the existence of residual reflection on the output facet, the LDA is virtually working in a compound cavity. The variation of residual reflectivitymay result in the changing of the working characteristics of the phase-locked LDA. In earlier analysis, was usually treated as a perturbation and was left out. But before the function of can be clearly understood, it is not proper to leave out. Hence, the influence of is included in our modeling. After reflection from the external mirror, the output field from a certain emitter will couple into every emitter with different portions. Generally speaking, the field coupled into the emitter itself and its neighboring emitters will be the strongest. Hence, we have further simplified the coupling matrix and get the analytical eigenvalue of the matrix's. The near-field amplitude distribution and far-field intensity are also presented.Furthermore, the threshold gain for the phase-locked LDA is deduced. The influences of the front facet reflection coefficient and the round cavity length L on the stability of the external phase-locking are discussed.