Bonn 2025 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 49: Poster – Photonics, Lasers, and Applications

Q 49.25: Poster

Mittwoch, 12. März 2025, 17:00–19:00, Tent

Frequency Response of Surface Bragg Gratings for Monolithic Extended Cavity Diode Lasers — •Sten Wenzel, Olaf Brox, Jörg Fricke, Igor Nechepurenko, and Andreas Wicht — Ferdinand-Braun-Institut (FBH), Gustav-Kirchhoff-Straße 4, 12489 Berlin

Monolithic extended cavity diode lasers (mECDL) are a compact, robust and efficient light source with ultra-low frequency noise well suited for optical quantum technologies such as optical atomic clocks and quantum sensors based on atom interferometry. The extended propagation section results in a narrow longitudinal mode spacing of the cavity. Hence, the frequency selective element utilized to establish single mode operation, in this case a distributed Bragg reflector (DBR), must provide a spectrally narrow resonance with a width of the order of a few tens of GHz. We achieve this by a DBR with a small coupling coefficient and increased length of 2 mm. Since the spectral characteristics of a DBR scale with its length, uncertainties in the grating design, which arise from potential shortcomings in the modeling or technological implementation, may lead to significant deviations between the expected (simulated) and real performance. We therefore developed and implemented a method for the characterization of the spectral reflectance and transmission of such gratings in ridge-waveguides by laser spectroscopy. In this work, we present our findings and compare our measurement results with the theoretical prediction.

Keywords: Bragg grating; ridge waveguide; higher order Bragg diffraction; coupling coefficient; radiation loss