Proceedings Article | 8 February 2007
Proc. SPIE. 6485, Novel In-Plane Semiconductor Lasers VI
KEYWORDS: Continuous wave operation, Clocks, Laser applications, Interferometry, Semiconductor lasers, Near field, Atomic clocks, Cesium, Indium gallium phosphide, Near field optics
Single frequency and single spatial mode diode lasers emitting at 852nm are strategic components for systems such as
atomic clocks (positioning systems for navigation, in space atomic clock like Galileo or Pharao (cold atom),
measurement of fundamental constants), or interferometry applications. We have developed the technological
foundations of lasers at 852nm to address these different applications. These include an Al free active region, a single
spatial mode ridge waveguide and a DFB (distributed feedback) structure.
The device is a separate confinement heterostructure with a GaInP large optical cavity and a single compressive strained
GaInAsP quantum well. For an AR-HR coated ridge Fabry Perot laser, we obtain a power of 230mW with M2=1.3.
An optical power of 150mW was obtained at 854nm, 20°C for AR-HR coated devices. We obtain a single spatial mode
emission and a SMSR over 50dB, both at 150mW.
DFB Lasers at 852.12nm, corresponding to the D2 caesium transition, were then realised with a power of 40mW per
facet, 37°C for uncoated devices. At 40mW, we determine a M2 value of 1.3. We measure a SMSR value around 50dB
between 10°C and 80°C.
On this last laser run, we obtain very homogeneous spectral linewidth values for five different lasers, measured with a
Fabry Perot interferometer. We obtain at 20°C a low average linewidth value of 1.40MHz and 1.10MHz at respectively
40mW and 20mW, together with a low standard deviation of 0.1MHz. At 852.12nm (37°C, 40mW), a low linewidth
value of 1MHz was measured, for one laser preliminary tested.
