Influence of the width of a gap separating sections of a C3 laser on its emission spectrum

An experimental investigation was made of how the width of a gap between sections in a two-section injection laser with optically coupled resonators influenced its emission spectrum. In the case of an arbitrary gap it was possible to select the current in the modulating section to excite lasing in the form of any longitudinal mode within the tuning range. Variation of the gap within a range of the order of one wavelength did not alter the direction of mode tuning by variation of the current in the modulating section.