Precision Experiments

Focus Field: Fundamentals of Mmetrology

Optical gain in group-III nitrides

Focus: 
Precision Experiments

Nitrides-based (GaN, AlN and InN and their alloys) semiconductors have been recognized as one of the most promising materials for realizing optical devices. These compounds were selected not only due to their wide direct energy gap but also due to their excellent physical properties such as e.g. hardness, physical and chemical stability etc. InGaN-based violet and blue laser diodes show high output power and low threshold current. They are already commercially available in a wide field of applications.

Mentor/s: 
Hangleiter
Institution: 
TU Braunschweig
Status: 
discontinued
Ph.D. student: 
Kruse

Absolute distance measurement

Focus: 
Precision Experiments

Most of the length measuring interferometers are working incrementally. Thus beam interruptions are causing errors in distance measurement. This interruptions might happen accidentally by parts moving through the beam or on purpose when the distance to different mirrors shall be measured. To afford distance measurements with possible beam interruptions an absolute length measurement is needed.

Mentor/s: 
Schulz
Mentor/s: 
Tutsch
Institution: 
Braunschweig IGSM
Institution: 
PTB
Status: 
discontinued
Ph.D. student: 
Sommerfeld

Advanced Electronic Systems for Improved Accuracy in Cesium Fountain Clocks

Focus: 
Precision Experiments
Mentor/s: 
Riehle
Mentor/s: 
Schilling
Institution: 
PTB
Institution: 
TU Braunschweig
Status: 
in progress
Ph.D. student: 
Kazda

Dissemination of ultra-stable optical frequencies over commercial fiber networks

Focus: 
Precision Experiments

The aim of the PhD work to investigate the performance of “dark fibers” which is used in commercial telecommunication for the transmission of ultra-stable optical frequencies. The optical fiber is sensitive to acoustic and temperature fluctuations, which in turn effects the stability of frequencies propagating in the fiber. Therefore, we developed a scheme to compensate the phase and frequency fluctuations in the fiber. A laser at 1542 nm is used to avoid high attenuation at other wavelengths.

Mentor/s: 
Ertmer
Mentor/s: 
Schnatz
Institution: 
PTB
Institution: 
Universität Hannover
Status: 
completed
Ph.D. student: 
Terra

Raman scattering in low dimensional, frustrated electron systems

Focus: 
Precision Experiments

Reliable reproducibility of measured values is vital in metrology. Therefore, it is of great importance to express every commensurable quantity through well-defined standards.

One of the most active fields in solid state physics deals with discovering new elementary excitations in form of so-called quasi particles. In the future, these quantized low energy excitations can be useful in metrology to help and improve the accuracy of formerly uncertain measurements (cf. Quantum Hall effect).

Mentor/s: 
Güttler
Mentor/s: 
Lemmens
Institution: 
TU Braunschweig
Status: 
completed
Ph.D. student: 
Wulferding
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