A temperature controlled multi-channel transmitter optical subassembly (TOSA) may be used in a multi-channel optical transceiver. The temperature controlled multi-channel TOSA generally includes an array of lasers optically coupled to an optical multiplexer, such as an arrayed waveguide grating (AWG), to combine multiple optical signals at different channel wavelengths. The lasers may be thermally tuned to the channel wavelengths by establishing a global temperature for the array of lasers and separately raising local temperatures of individual lasers in response to monitored wavelengths associated with the lasers. A temperature control device, such as a TEC cooler coupled to the laser array, may provide the global temperature and individual heaters, such as resistors adjacent respective lasers, may provide the local temperatures. The optical transceiver may be used in a wavelength division multiplexed (WDM) optical system, for example, in an optical line terminal (OLT) in a WDM passive optical network (PON).