Optical parametric oscillator for molecular spectroscopy

• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: Funded in 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 440461823

The optical parametric oscillator applied for shall be used for different purposes:Research Project I: Precision Measurement of Rotation-Vibration Transitions in Hydrogen MoleculesPrecision spectroscopy of rotational-vibration transition frequencies in hydrogen molecules opens a new approach to several fundamental constants (Rydberg constant, mass ratios of deuteron to proton, electron to proton, proton charge radius, deuteron charge radius, and quadrupole moment of deuteron). The optical parametric oscillator is required (i) for the internal state preparation of hetero- and homonuclear hydrogen molecules, (ii) for non-destructive read-out of the state of heteronuclear molecule ions using a novel method, and (iii) for conducting feasibility studies on novel (electrically dipole-forbidden) transitions.The obtained results are completely independent from complementary measurements of proton, deuteron and electron masses with Penning traps, as well as from hydrogen and deuterium spectroscopy. Thus hydrogen molecular ion spectroscopy is an important verification of these measurements and improves the consistency and probably also the accuracy of the fundamental constants.In addition, hydrogen molecular ions are also test systems that can be used to test novel techniques, which can then be transferred to other molecular ions.Research Project II: Studies on optical materials for monolithic optical resonatorsIn the future, systematic measurements of the optical absorption of silicon crystals in the near and mid infrared range are planned (1.4 to 4.0 µm, emission range of the requested optical parametric oscillator), both at room and cryogenic temperatures. The aim is to identify crystals of different manufacturers and associated wavelengths with very low absorption losses. Once a suitable material has been identified, a monolithic resonator is designed, constructed, operated and characterized under suitable vacuum conditions.A passive monolithic resonator opens up new possibilities for fundamental physics. It can be used to detect a time-dependent (hypothetical) fundamental field coupling to the fine structure constant. Dark matter could contain such fields.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Optisch parametrischer Oszillator für die Molekülspektroskopie
• Instrumentation Group: 5700 Festkörper-Laser
• Applicant Institution: Heinrich-Heine-Universität Düsseldorf
• Leader: Professor Stephan Schiller, Ph.D.