Measurements of mode partition noise of laser diodes

This is the authors' abstract. We don't add key points for this paper.

Mode partition noise may become the dominant performance limitation for single-mode fiber systems. We define the mode partition coefficientkfor laser diodes which can be used as a universal index, like threshold current and spectral width, to characterize laser diodes. Thekvalue varies between 1 and 0, and for largerk, the mode partition noise will be higher. We also demonstrate two simple techniques for measuringk: the low-pass filter method and the sampling method. We discuss thekvalues measured under different operating conditions (pulse width, dc bias) for several types of laser diodes,kvalues are around 0.4-0.6 with short pulse width (1.5-5ns), and decreases to 0.14 pulse width of 50 ns. The largestkvalues were obtained for a laser exhibiting strong relaxation oscillation. For that laser,kdid not depend on the pulse width. Thekvalue is an important factor for system and fiber design as well as laser diode design.