MIOMD-X, September 5-9, 2010, Shanghai, China. P- 28. Diagnostic and characterization of VCSEL diodes based on GaSb substrate
Diagnostic and characterization of VCSEL diodes based on GaSb substrate
E. Hulicius1*, J. Pangrác1, J. Oswald1,T. Šimeček1, J. Vyskočil1, I. Matulková2, J. Cihelka2, Z. Zelinger2, S. Civiš2, Z. Chobola3* Corresponding author email: [email protected]
1Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i.,Prague, Czech Republic
2 J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i.,Prague, Czech Republic
3Brno University of Technology, Faculty of Civil Engineering, Brno, Czech Republic
Vertical-Cavity Surface-Emitting Laser (VCSEL) diodes are among the youngest members of the semiconductor laser diode family. The aim of our work focuses on the measurement of the properties (the spectral range of
A new type of VCSEL GaSb-based diodes for the 4250 cm−1 (around 2.3 μm) wavelength region have been developed at WSI of the TU München. The laser structures were prepared by MBE on n-type GaSb, with the n-contact at the bottom. The bottom Bragg epitaxial mirror consists of twenty-four couples of AlAsSb/GaSb layers. The active zone of these lasers consists of five 11-nm-thick Ga0.65In0.35As0.1Sb0.97 quantum wells surrounded by Al0.35Ga0.65As0.03Sb0.97 barriers. The device employs a p-GaSb/n-InAsSb-buried tunnel junction (5-8 μm in diameter) as a current aperture and replaces the high loss p-material by n-type material. The Ti/Pt/Au ring contacts are sputtered on InAsSb contact layer. The dielectric mirror from four couples of Si/SiO2 layers is placed at the top of the laser structure above the buried tunnel junction.
VCSEL structures and their preparation are described by our colleagues from WSI TU München here during MIOMD 10.
Fine tuning of these lasers can be realized by changing the temperature or the injection current. Lasers operate in the CW regime at room temperature with an output power around 50 μW. The threshold current is around 1.5 mA and its temperature dependence is relatively weak.
the laser emission, temperature, current tunability, far-field and lifetime) of experimental VCSEL diode lasers based on GaSb and operating in the wavelength infrared region around 2.3 μm.
These lasers were prepared in frame of EU project NEMIS at TU München.A high-resolution spectrometry was used for laser diagnostics.
FAR FIELD MEASUREMENT
Ageing test equipment
Ageing box with holders for 10 individual lasers on the headers under CW current provided by ten stabilized power sources and a temperature stabilized detector that can be regularly precisely attached to these lasers to monitor their relative optical power output was used.
For special purposes also two positions have been prepared for pulsed pumping by 1μs pulses with up to 100 kHz repetition frequency with pulsed detection using lock in amplifier. These positions enable to measure lasers with higher currents and worse heat dissipation.
Increase of output power of the green-marked laser A1244 can be explained by changes of its far field.
FF spectrum of laser A1244 (green-marked in the Ageing part,left Fig.) after 1500 and 9020 hours ageing, respectively.
ELECTRICAL NOISE LASER MEASUREMENT
HIGH RESOLUTION MODE SPECTRA MEASUREMENT
Plot of log I versus lin U and log I versus log U for different laser diodes in the forward bias direction.
The noisespectral density as a function of forward bias and load resistor RL=1k Ω for different laser diodes.
The authors gratefully acknowledge the financial support by the European Union via NEMIS (contract no. FP6-2005-IST-5-031845), research center LC-510, and the program MSM 6840770014 and K. Kashani, A. Bachmann and Prof. M.-C. Amann from the Walter Schottky Institut for providing the VCSEL samples and O. Petříček for ageing measurements. This work is the part of the research programs of the Grant Agency of the Academy of Sciences oftheCzech Republic (Grant No. A400400705), the Ministry of Education, Youth and Sports (COST MP0702 and COST 729) and the research program of Institute of PhysicsAS CR 10100521.