Abstract: We present a novel superluminescent diode (SLD) with high optical performances for hardened neutron irradiation. The degradation of the light output from the SLDs is caused by a reduction of the minority carrier lifetime resulting from displacement damage after high-energy neutron irradiation. The SLDs with a higher pre-irradiation light output will be less sensitive to radiation. We have selected an InGaAsP/InP multi-quantum well (MQW) as the active region structure for its performance, its high optical gain and minute active region. Graded-index separate-confinement-heterostructure (GRIN-SCH) has been applied for the waveguide structure. A specific absorbing region and anti-reflective coatings have been designed and optimized. Moreover, the radiation test results indicate that the SLD with an InGaAsP/InP MQW structure has better neutron hardening ability than the SLD with DH structures after a 6 × 10¹³-1 × 10¹⁴ n/cm² 1 MeV neutron irradiation.

Key words: superluminescent diode