Ms. Tabitha Ballmann Profile

Tabitha Ballmann

at Univ Stuttgart

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Publications (4)

Proceedings Article | 16 February 2005 Paper

Red VCSEL for automotive applications

Robert Rossbach, Tabitha Ballmann, Rainer Butendeich, Ferdinand Scholz, Heinz Schweizer, Michael Jetter

Proceedings Volume 5663, (2005) https://doi.org/10.1117/12.597025

KEYWORDS: Vertical cavity surface emitting lasers, Aluminum, Modulation, Gallium, Temperature metrology, Reflectivity, Data modeling, Oxides, Aluminium gallium indium phosphide, Interfaces

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Proceedings Article | 20 December 2004 Paper

Red light VCSEL for high-temperature applications

Michael Jetter, Robert Rossbach, Rainer Butendeich, Ferdinand Scholz, Tabitha Ballmann, Heinz Schweizer

Proceedings Volume 5594, (2004) https://doi.org/10.1117/12.578279

KEYWORDS: Vertical cavity surface emitting lasers, Aluminum, Reflectivity, Mirrors, Gallium, Temperature metrology, Aluminium gallium indium phosphide, Oxides, Resistance, Oxidation

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Proceedings Article | 25 October 2004 Paper

Analysis of the modulation behavior of red VCSELs

Tabitha Ballmann, Robert Rossbach, Michael Jetter, Michael Jutzi, Manfred Berroth, Heinz Schweizer

Proceedings Volume 5597, (2004) https://doi.org/10.1117/12.580311

KEYWORDS: Vertical cavity surface emitting lasers, Modulation, Picosecond phenomena, Data communications, Quantum wells, Eye, Photodiodes, Laser damage threshold, Indium gallium phosphide, Phase only filters

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Proceedings Article | 8 December 2003 Paper

Red surface emitters: powerful and fast

Heinz Schweizer, Tabitha Ballmann, Rainer Butendeich, Robert Rossbach, Bernd Raabe, Michael Jetter, Ferdinand Scholz

Proceedings Volume 5248, (2003) https://doi.org/10.1117/12.512626

KEYWORDS: Vertical cavity surface emitting lasers, Modulation, Data communications, Laser applications, Gallium, Indium gallium phosphide, Temperature metrology, Oxides, Aluminum, Quantum wells

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Vertical cavity surface emitting lasers (VCSEL) in the GaInP/AlGaInP material system have experienced a rapid development in their short history. In general lasers from that material system are suitable for a huge number of applications beginning with TV lasers and high power lasers for edge emitters, continuing with optical data storage, medical applications as well as data communication in cars, air planes, offices and between computers as application field for VCSELs. Especially automotive applications show the highest requirements on a laser with respect to operation temperature and power. In this talk we draw out the problems of the material system AlGaInP and its implications for laser applications. We discuss the epitaxial and technological solutions to overcome at least a part of these inherent problems. We will discuss the possible power that we can expect from VCSELs emitting in the range between 650 nm to 670 nm. We got from our lasers 5 mW, CW @ RT, 670nm and 2.5mW, CW@RT, 650 nm. We emphasize the role of doping, Bragg mirror grading, suitable detuning of cavity mode and gain, and optimisation of the contact layer and control of the oxide aperture in the VCSEL structure to get improved operation characteristics at higher temperatures. From the analysis of high frequency measurements, we could evaluate modulation bandwidths between 4 GHz and 10 GHz. The application of polyimide as a dielectric isolation material shows the potential to obtain modulation bandwidths beyond 10 GHz. For the intrinsic modulation bandwidth we get a value of 25 GHz, which is near the value edge emitters show. A more detailed discussion on photon lifetimes and carrier transport times will be given in the talk. Red light emitting VCSELS driven with short current pulses showed laser emission up to + 160°C case temperature. Thus, a CW operation up to +120°C can be expected after further improvement of power generation (decrease of series resistance) and heat spreading (optimized contacts and mounting). From these characteristics we can conclude that AlGaInP-surface emitting lasers have a real potential as low cost lasers for automotive applications as we all as data communication applications up to 10 GHz.

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