Defect-related optical absorption bands in CdSiP sub(2) crystals

• Published in: Optical materials express Vol. 7; no. 3; pp. 658 - 664
• Main Authors: Scherrer, E M, Kananen, B E, Golden, E M, Hopkins, F K, Zawilski, K T, Schunemann, P G, Halliburton, L E, Giles, N C
• Format: Journal Article
• Language: English
• Published: 01-03-2017
• Subjects: Absorption spectra; Crystal defects; Crystals; Decay; Lasers; Monitors; Silicon; Vacancies
• ISSN: 2159-3930; 2159-3930
• DOI: 10.1364/OME.7.000658

When used as optical parametric oscillators, CdSiP sub(2) crystals generate tunable output in the mid-infrared. Their performance, however, is often limited by unwanted optical absorption bands that overlap the pump wavelengths. A broad defect-related optical absorption band peaking near 800 nm, with a shoulder near 1 [mu]m, can be photoinduced at room temperature in many CdSiP sub(2) crystals. This absorption band is efficiently produced with 633 nm laser light and decays with a lifetime of -0.5 s after removal of the excitation light. The 800 nm band is accompanied by a less intense absorption band peaking near 1.90 [mu]m. Data from eight CdSiP sub(2) crystals grown at different times show that the singly ionized silicon vacancy (V sub()Si is responsible for the photoinduced absorption bands. Electron paramagnetic resonance (EPR) is used to identify and directly monitor these silicon vacancies.