Room temperature pulsed oscillation of GaAlAs/GaAs surface emitting junction laser

Abstract

Theoretical and experimental work has been done to reduce the threshold current density J <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> of a GaAlAs/GaAs surface emitting junction laser emitting at a wavelength of 0.87 μm. The threshold current density J <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> has been obtained as a function of active layer thickness <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</tex> and the reflectivity of the mirrors. The necessary reflectivity for threshold is 95 percent in the case of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d = 1-2 \mu</tex> m to achieve <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J_{th} = 25</tex> kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at room temperature. In order to realize this high reflectivity without deteriorating the p-side ohmic contact, we have proposed a new surface emitting laser structure with a ring electrode for the p-side contact. Room temperature pulsed oscillation has been realized. The minimum threshold current was about 310 mA at room temperature under pulsed condition. The corresponding J <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> at the active layer is about 25 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . This indicates that we have realized the high reflectivity. The maximum light output peak power was more than 5 mW. The beam was as sharp as 10° (FWHM) and linearly polarized. A single longitudinal mode was observed against the temperature variation of 80 K. Fabrication processes and some lasing performances are described.