The quantum-confined Stark effect is employed to form an integral reverse-biased absorber in a GaInAsP edge-emitting light emitting diode. Optical low coherence reflectometry is used to measure the magnitude of reflections through this absorber. Front facet-back facet roundtrip reflection magnitudes are below -110 dB in devices having an antireflection coating on the front facet only. All other round trip reflections are below -80 dB. This device provides a wide usable dynamic range in optical low coherence reflectometry measurements.