Three-section PDBR lasers with narrow spectral linewidth (<10 MHz) under tuning

The spectral linewidth behavior under wavelength tuning of tunable lasers is a key point as far as local oscillator applications for a coherent multichannel (CMC) system is foreseen. At this time, spectral linewidth broadening under tuning operation has been observed and this is the main problem for monolithic tunable lasers as well as for DBR type lasers1 or TTG2 structures.