|
An all-optical telecommunications network requires all-optical routers. These routers would be able to process optical
signals directly, without the transformation to the electrical domain. Thus, optical routers have the potential to accelerate
telecommunications, i.e. to enhance the data rate and to minimize the latency times. Furthermore, since the double
transformation at each network node can be omitted, they could be able to reduce the energy consumption of
telecommunications. Key elements of optical routers are optical buffers, which are able to store the optical packets prior
to processing in order to avoid congestion. Therefore, many different concepts for the realization of optical buffers have
been presented so far. Most of these can just store or delay on-off keyed (OOK) signals. However, in optical
telecommunications advanced modulation formats will be increasingly used because they are able to improve the
transmission properties and to take advantage of the capacity of optical fibers. Thus, advanced modulation formats can
drastically increase the transmissible data rates. Most of these advanced formats modulate the carrier’s phase or are a
combination of amplitude and phase modulation. Here the storage of amplitude and phase modulated data packets with
the so called quasi-light-storage (QLS) method will be shown. The QLS relies on the time-bandwidth coherence of each
signal. Thus, as long as the sampling theorem in the frequency domain is not violated, a distortion-free storage of optical
data packets with a delay-bandwidth product (DBP) of several thousand bits is possible. Here we will discuss the
applicability of the QLS method to advanced modulation formats and we show experimental results of the tunable alloptical
storage of OOK modulated signals with a DBP of 160 bit and the storage of phase shift keyed signals with a DBP
of 60 bits.
|
