We propose an injection locked triple contact Fabry-Perot laser diode (TC F-P LD) for an uncooled wavelength division multiplexing systems. By controlling injection currents to three electrodes of the TC F-P LD, we are able to tune the cavity mode for an optimum injection locking without using temperature control. Then, we transmitted 20-Gb/s/channel quadrature phase shift keying signal using the LD as either an optical carrier or a local oscillator. We identified contributions of the performance degradation as: 1) intensity noise resulting from a finite common mode rejection ratio associated with a relative intensity noise and 2) decrease of the effective LO power for coherent detection. Finally, we show the uniform bit error rate performance with change of the injection wavelength by 2.8 nm. This is corresponding to 28 degrees C change of operating temperature.