H. Ishii et al., NARROW SPECTRAL LINEWIDTH UNDER WAVELENGTH TUNING IN THERMALLY TUNABLE SUPER-STRUCTURE-GRATING (SSG) DBR LASERS, IEEE journal of selected topics in quantum electronics, 1(2), 1995, pp. 401-407
Narrow spectral linewidth characteristics are demonstrated in thermall
y wavelength tunable super-structure-grating distributed Bragg reflect
or (SSG-DBR) lasers, SSG reflectors were fabricated with a multiple-ph
ase-shift insertion method using electron-beam lithography. The phase
distributions of the SSG's were optimized to obtain uniform reflection
peaks, Incorporating thin-film Pt heaters into the lasers enables us
to tune the lasing wavelength by the thermal effect. The device has a
wide quasi-continuous tuning range of 40 nm with CW operation at room
temperature, The spectral linewidths, frequency fluctuations, and tuni
ng speed in thermal wavelength tuning were studied compared with those
in electrical tuning, Experimental results showed that thermal tuning
does not influence frequency fluctuations and spectral linewidths, bu
t the tuning speed was slow. Narrow spectral linewidths below 400 kHz
were achieved in a wide quasi-continuous tuning range of 40 mn.