Highly compact dual-mode semiconductor laser sources get
more and more attention in different application fields such as radar,
security and personal communication systems. When the two generated
wavelengths are detected within the same photodetector, an electrical signal
which frequency is the difference between the frequencies of the two optical
modes will be issued. We report on an integrated semiconductor device which
is composed of two in-line DFB sections that are using the same optical
waveguide structure. The so generated dual-mode spectrum can be adjusted
first, by the difference in the grating parameters of each DFB section and
second, by their respective driving current. We will report on the
characterisation of such a device focusing on tunability and linewidth
aspects that are of prime importance in above mentioned applications.