We describe a novel dense wavelength-division multiplexed systems (DWDM) system where by introducing orthogonality between adjacent channels and by using overlapping arrayed waveguide grating filter profiles, laser transmitters may operate without the need for thermoelecric cooling. Compared with a traditional DWDMsystem, a power consumption saving of up to 68% may be realized using this scheme. Results of a proof-of-principle 100 Gb/s (10×10 Gb/s) experiments that use alternating NRZ and Manchester (CAP-2Q) modulation is reported.