Modal analyses of Talbot cavity eigenmodes are performed for a finite diode laser array using a simple finite external mirror and a patterned external mirror. At a full round-trip Talbot length, the in-phase and oscillating-phase modes of the cavity with a simple flat mirror have slightly different thresholds. The increased modal separation from a patterned-mirror Talbot resonator is shown to be larger than a flat-mirror resonator with a round-trip distance of half a Talbot length. In all these cases, steady-state oscillation is shown to consist of either the in-phase or oscillating-phase mode. The inherent flaw of the Talbot resonator suggested by P. Latimer [Appl. Phys. Lett. 62, 217 (1993)] is thus shown to be a simple matter of modal separation rather than a "violation of the widespread assumption of grating self-imaging".
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