Optical properties of a 1.3-µm InGaAsP superluminescent diode

The optical properties of a 1.3-µm InGaAsP-InP buried heterostructure (BH) superluminescent diode (SLD) are described. The spectra of this device exhibit a large number of longitudinal modes. The light output at constant current from an SLD has a strong temperature dependence in the superluminescent region (high currents) and week temperature dependence in the spontaneous region (low currents). This severe temperature dependence will limit the systems application of this type of device unless thermoelectric cooling is used. The coupling efficiency (butt-coupling) into a 0.23-NA 50-µm-diameter graded index fiber is 26 percent. A model of the SLD including a temperature dependent nonradiative mechanism (same as in 1.3-µm InGaAsP lasers) suggests that the strong temperature dependence in the superluminescent region is a fundamental property of the device.