Elisabeth Penard
Quasi-Optic Electrooptic Modulator on LiNbo3
Abstract:This research was conducted within the frame of the Millimeter
wave fiber optic links project, now under development at the ATR
Optical and Radio Communications laboratories. Optic fibers provide,
due to the low transmission loss and the very high bandwith
capacity, new facilities for routing high data rate information and
for the development of wireless communications. The feasibility of
such systems implies to master both the technology of optic fiber
and millimeter wave, but moreover these new techniques will
emerged if we are able to provide simple, and low cost transducers
for converting a millimeter wave signal into an optical signal, and
vice versa. Figure 1-a below shows a simplified architecture of an
millimeter wave optical link. On the up link data are transfered on a
fiber from the central station to the remote base station, the
simplest system architecture requires to develop high frequency
optical modulators, and also high frequency photodetectors. On the
down link data are sent from the remote base station to the central
station, the microwave signal received by the antenna modulates the
optical sub-carrier, there are in that case two alternative the first
one is to down convert and then directly modulate a laser diode,
but then a mixer is needed in the base-station which increases the
cost and complexity of the receiver, the second one (Figure 1-b) is
to use an external modulator for direct modulation of the optical
subcarrier at millimeter wave frequency.