Streak camera - time dependent spectroscopy

Our setup enables a detailed characterization of the dynamical behavior of lasers using the combination of a monochromator and Streak camera. This combinations results in a very high temporal and spectral resolution. The streak camera allows many investigation configuration due to its internal experimental modes: time-averaged investigation with a typical integration of over ≈ 10 ⁶, single shot measurements for individual pulse analysis, and photon counting to count individual photons and thus be able to analyze light emission with very low intensity. Especially single shot measurement ensure an investigation of temporal dynamics, which can also fluctuate over several pulses. With this setup we can analyze the laser in pulse operation from 1ns up to 1ms.
In general, we are investigating the time-dependent electroluminescence (EL) behavior of different InGaN/GaN lasers structures. In EL analyses, the light emission is produced electrically, i.e. an emission pulse is generated by applying a voltage pulse to the semiconductor material. The analyzed structures consist of advanced blue and green lasers; from commercial laser diode to novel epitaxial design. Different projects with various universities and research institutes involve investigations with this setup. Novel designs include photonic crystal surface emitting lasers (PCSELs) and laser diodes that contain multiple active regions, which are connected with tunnel junctions. Further informations can be found under projects-Multi DFB junctions .
The time-dependent analyze can also be combined with our µ-PL setup to investigate photoluminescence of different structures. It is also possible to guide the pulsed light emission via coupling into fibers to another setup in our laboratories in order to perform gain measurements in pulsed mode.

We not only study the lasers through experimental investigations, but also develop our own simulations to analyze the properties of the lasers. The aim is to gain an understanding of laser physics with its time-dependent properties, dynamic mode interaction and optical losses. Furthermore, various signal modulations are carried out.

analysis example:

latest theses:
J. Tepaß: Influence of the device structure on the dynamics of InGaN laser diodes containing tunnel junctions, Masterarbeit
L. Uhlig: Dynamics of broad-ridge AlGaInN laser diodes, Dissertation

latest publicationen:
L. Uhlig, et al., IEEE Journal of Selected Topics in Quatum Electronics (2024), "Mode Competition Between Longitudinal and Lateral Modes in III-Nitride Broad-Ridge Laser Diodes"
J. Tepaß, et al., pss(a) (2024), "Dynamical Behavior of a Stacked Blue Laser Diode Consisting of Two Active Regions with Wide InGaN Quantum Wells and Two Tunnel Junctions"
L. Uhlig, et al., Physical Review B 108 (2023), "Transition between quantum confinement and bulklike behavior in polar quantum wells"