Leakage current measurement in multielectrode lasers using optical low-coherence reflectometry

In multielectrode lasers, the interelectrode spacing is often reduced in order to avoid the saturable absorber effect in this region, which could cause instabilities of the laser. This leads to an interelectrode leakage current between adjacent electrodes. Measuring this leakage current by conventional means is very difficult and often inaccurate, in particular, when the part of the leakage current reinjected into an active region has to be determined. Based on optical low-coherence reflectometry, a method is presented which allows the measurement of this leakage current with an error smaller than 10%. Additionally, the effective group indexes of the laser waveguide and its bulk material will be determined.