MBI Staff Member – Personal info

Research

High-power semiconductor lasers are the most efficient man-made light sources, and can convert more than 80% electric energy into light. Currently emission powers of one kW continuous-wave powers are extracted from a single monolithic semiconductor chip. We are interested in the intrinsic limitations of such optoelectronic devices in terms of output power, beam quality (brightness) and lifetime (reliability). For this purpose, we analyze devices, but also their components such as surfaces and interfaces or gain materials such as quantum wells, superlattices and quantum dots.
For our experiments, we use optical tools, in particular transient spectroscopy that represents a generic competence of MBI. Such work is naturally carried out as collaborative work with device vendors, who provide us with high-quality industry-grade devices and structures. The use of such devices ensures high reproducibility and the chance to get general results, which not depend on the particular device structure that was studied. In BMBF-projects such as BlauLas, we work together with Osram OS (Regensburg), Dilas GmbH (Maiz) and Laserline GmbH (Mülheim) or in the frame of bilateral research contracts with Lumentum (Santa Clara) and 3S-Photonics (Nozay).
The material basis of the investigated devices is now focused to GaN-based wide-bandgap devices emitting in the ultraviolet to blue spectral regions. The figure shows damage patterns as observed in 450-nm emitting high power diode lasers after it experienced the so-called catastrophic optical damage in short-pulse operation.

Subfigure (a) shows the damage patterns at the font facet, where the light leaves the device (red circle), while (b) shows the same region from the side. A channel is visible which burned into the device and ends ~80 µm underneath the front facet; see (c). Subfigure (d) shows the end of this channel in higher resolution. The quantum wells, i.e. the gain medium are well resolved.

 

Curriculum vitae

2018  East China Normal University as ECNU High-End Expert, China

1999  Visitor at the RIKEN-Institute Sendai, Japan

1995 - present: Senior researcher at MBI

1993-1995: Visiting professor at Georgia Tech Atlanta, USA

1986-1989: R&D group leader in a subcontract "Optical characterization of II-VI materials for IR quantum detector fabrication".

1984-1986: R&D work in a subcontract to "Carl Zeiss Jena" company to develop diode lasers for an IR diode laser spectrometer.

1981-1984: PhD student, Dr. rer. nat. in Physics, summa cum laude, Humboldt University, Berlin 1984 Dissertation: Study of the optical properties of n-Pb1-xSnxTe/p-Pb1-xSnxTe/p-PbTe-heterostructures by means of photoluminescence and injection-luminescence.

1977-1982: Physics studies, Diploma in Physics summa cum laude, Humboldt University, Berlin 1982 Thesis: Luminescence properties of lead salts for optical and electrical excitation.

MBI Publications

  1. Interdot energy transfer in a system of coupled InAs/GaAs quantum dots

    Y.I. Mazur, J.W. Tomm, G.G. Tarasov, H. Kissel, C. Walther, Z.Ya. Zhuchenko, W.T. Masselink

    Physica E: Low-dimensional Systems and Nanostructures 13 (2002) 255-258
  2. Simultaneous quantification of strain and defects in high-power diode laser devices

    J.W. Tomm, A. Gerhardt, T. Elsaesser, D. Lorenzen, P. Hennig

    Applied Physics Letters 81 (2002) 3269-3271
  3. Diode laser testing by taking advantage of its photoelectric properties

    J.W. Tomm, A. Gerhardt, D. Lorenzen, P. Henning, H. Roehle

    SPIE Proceedings 4648 (2002) 9-21
  4. The impact of defects to minority-carrier dynamics in heavily doped GaAs:C analyzed by transient photoluminescence spectroscopy

    J.W. Tomm, A. Maaßdorf, Y.I. Mazur, S. Gramlich, E. Richter, F. Brunner, M. Weyers, G. Tränkle, V. Malyarchuk, T. Günther, Ch. Lienau

    Materials Science and Engineering B 91-92 (2002) 25-28
  5. Radiative recombination features of metastable quantum dot array

    V.G. Talalaev, B.V. Novikov, G. Gobsch, R. Goldhahn, N. Stein, J. W. Tomm, A. Maasdorf, G.E. Cirlin, V.N. Petrov, V.M. Ustinov

    Physica status solidi (b) 224 (2001) 101-105
  6. Photoluminescence decay time measurements from self-organized InAs/GaAs quantum dots grown on misoriented substrates

    A.S. Shkolnik, E.B. Dogonkin, V.P. Evtikhiev, E.Yu. Kotelnikov, I.V. Kudryashof, V.G. Talalaev, B.V. Novikov, J.W. Tomm, G. Gobsch

    Nanotechnology 12 Institute of Physics Publishing (2001) 512-514
  7. Staircase-like spectral dependence of ground-state luminescence time-constants in high-density InAs/GaAs quantum dots

    Yu. I. Mazur, J. W. Tomm, V. Petrov, G. G. Tarasov, H. Kissel, C. Walther, Z. Ya. Zhuchenko, W. T. Masselink

    Applied Physics Letters 78 (2001) 3214-16
  8. Large optical cavity waveguides for high-power diode laser applications

    V. Malyarchuck, J.W. Tomm, T. Günther, R. Müller, R. Kunkel, C. Lienau, J. Luft

    SPIE Proceedings 4287 (2001) 111-7
  9. Near-field photocurrent imaging of the optical mode profiles of semiconductor laser diodes

    T. Guenther, V. Malyarchuk, J. W. Tomm, R. Müller, C. Lienau, J. Luft

    Applied Physics Letters 78 (2001) 1463-5
  10. Automated high-accuracy measuring system for specular micro-reflectivity

    R. Grunwald, S. Nerreter, J.W. Tomm, S. Schwirzke-Schaaf, F. Dörfel

    SPIE Proceedings 4449 (2001) 111-118

Other Publications

Books

Juan Jiménez and Jens W. Tomm, "Spectroscopic Analysis of Optoelectronic Semiconductors", Springer Series in Optical Sciences Vol. 202 (Springer, 2016).

Jens W. Tomm and Juan Jiménez, "Quantum-Well Laser Array Packaging", Nanoscience and Technology Series (McGraw-Hill, 2007).