High-Power Al-Free Active Region (λ = 852nm) Laser Diodes For Atomic Clocks and Interferometry Applications

摘要

We have developed Fabry-Perot lasers at λ=852nm, using an aluminium free active region with the aim to develop a single-frequency and single spatial mode device for atomic clocks and interferometry applications. The device is a separate confinement heterostructure with a GalnP large optical cavity and a 8nm compressive-strained GalnAsP quantum well. The broad-area (100μm wide) laser diodes are characterised by low internal losses ( < 3 cm~(-1)), a high internal efficiency (94%) and a low transparency current density (100A/cm~2) which illustrates the quality of the laser structure. For an AR/HR coated 2mm long broad area laser diodes we measure a low threshold current density (245A/cm~2) and a high slope efficiency (0.9 W/A). We obtain an optical power of more than 5.5W (I= 8.5A), under CW operation at 15℃, with a maximum wall-plug efficiency of 0.45. The lasing emission is achieved up to at least 115℃ An optical power of more than 1.4W is obtained at 100℃ (I=3.6A). A power of 1.2W (I=1.7A, 15℃) is achieved at 852nm. For an AR/HR coated 2mm long 4μm wide ridge waveguide laser diode, we obtain a low threshold current (46mA) and a high slope efficiency (0.9W/A). We obtain 852nm wavelength at 145mW (I=200mA, 15℃). We measure an optical power of 180mW (I=240mA) in a single spatial mode with the beam quality parameter M~2=1.5. At 180mW both near and far field are gaussian-shaped with respective full widths at 1/e~2 of 6μm and 12°.