An experimental method for accurate measurements of the reflectivity spectrum of mirrors is presented. It combines the noise reduction obtained with multiple beam reflections on two identical mirrors; high-beam quality, owing to the use of single-mode optical fibers; and high immunity against intensity variations of the beam. This method is demonstrated for characterizing a 30-period GaAs/Al0.65Ga0.35As distributed Bragg reflector designed for long-wavelength vertical-cavity surface-emitting lasers. Its peak reflectivity is found to be 99.43 ∓ 0.04% at 1.562 μm, and an optical absorption coefficient of α = 36 ∓ 6 cm−1 is derived. The peak internal reflectivity of this distributed Bragg reflector used as the top mirror in a wafer-fused vertical-cavity surface-emitting laser is calculated to be 98.87 ∓ 0.12%, and the transmission is 0.28%.
© 1998 Optical Society of America
(120.5700) Instrumentation, measurement, and metrology : Reflection
(220.4840) Optical design and fabrication : Testing
(230.4040) Optical devices : Mirrors
(230.4170) Optical devices : Multilayers
(250.7260) Optoelectronics : Vertical cavity surface emitting lasers
Claude-Albert Berseth, Arthur Schönberg, Oliver Dehaese, Klaus Leifer, Alok Rudra, and Eli Kapon, "Experimental Method for High-Accuracy Reflectivity-Spectrum Measurements," Appl. Opt. 37, 6671-6676 (1998)