Abstract

We present results of a cleaved coupled cavity (C³) laser [1-3] analysis which in contrast to previous studies incorporsates all the following: (1) a model of the gain variation with pumping current and photon energy [4]; (2) the refractive index dependence of the active region injection current [5]; (3) traveling wave equations for each laser segment; and (4) spontaneous emission as the laser excitation [6]. Based on our realistic formulation, we have developed a numerical algorithm to solve for the precise current required by one segment to attain threshold when the current in the other segment is specified. The calculation determines the minimum threshold current, whereas in analyzing this complex device it is possible to compute false higher thresholds. Simultaneously, the calculation finds the spectrum as a single lasing mode. Thus we obtain the spectral behavior as either segment current is varied and we are able to illustrate the progression of longitudinal mode hops through the spectral line. In addition, we calculate quantitatively previously unreported jumps from one extreme of the gain spectrum to the opposite extreme in particular current ranges. We study both configurations in which the two cavities are of similar lengths (called long-long) and of quite dissimilar lengths (long-short). The results illustrate that device behavior is very' sensitive to the gap spacing between the two segments.

© 1984 Optical Society of America