A simple and accurate method for measuring the front facet modal reflectivity of a Fabry–Perot laser diode is presented. In this method, optical feedback from an external mirror of known reflectivity, Rext, is used to alter the laser diode threshold current. The effect of the external mirror and front facet reflectivities on the threshold current then allows for a measurement of the front facet modal reflectivity of the laser diode and is theoretically and experimentally studied. This method was used to measure a facet reflectivity of R2 = 0.0151(+0.0018/-0.0032) [R2 = 0.00592(+0.00085/-0.00123)] for a commercially antireflection-coated facet of a laser diode with a center wavelength of 795 nm (935 nm). The results of the reflectivity measurements based on the threshold current as a function of the external mirror reflectivity are compared with the results of the reflectivity measurements based on modulation depth of the optical spectrum [IEEE J. Quantum Electron. QE-19, 493 (1983)].
© 2000 Optical Society of America
Original Manuscript: September 15, 1999
Revised Manuscript: May 18, 2000
Published: August 20, 2000
Kevin S. Repasky, Gregg W. Switzer, Casey W. Smith, and John L. Carlsten, "Laser diode facet modal reflectivity measurements," Appl. Opt. 39, 4338-4344 (2000)