Impact of Laser Intensity Noise on Multiport Optical Homodyne Receivers

This paper describes initial experimental results obtained with a multiport optical homodyne receiver employing a DFB laser. The receiver performance is found to be limited by the intensity noise of the local oscillator rather than by the phase noise, even when the product of the IF linewidth and the bit duration is 0.56. A relative intensity noise level of -125 dB/Hz is found to be insufficient for a satisfactory receiver performance; a level of -140 dB/Hz will be needed to make the receiver useful.