Sub-Lambda Photonically Switched Network (SLPSN) solutions are able to improve the use of capacity in data networks while limiting the growth of energy consumption. Recently, we have proposed the TIme and Spectral optical Aggregation (TISA) concept in order to respond to operator's needs of flexibility in the allocation of network resources. Additionally, the TISA solution makes a better use of already deployed network resources. In TISA, each source sends data in the form of bursts that only occupies a spectral sub-band, thus offering purely optical aggregation and disaggregation in both time and spectral domains with the finest possible granularity. Wavelength-based routing is then performed passively in the network. A fast tunable laser with low phase noise is necessary to implement the TISA transmitter but, current existing commercial lasers can't meet these two specifications. In this paper we present a transmitter solution fulfilling the switching time and low phase noise requirements. We give experimental results of a CO-MB-OFDM transmitter realized by combining optical gates and low phase noise lasers and report its performance in a back-to-back configuration.