Cryogenic temperatures A.Fibres 1 Absorption cells 1 Applied research 1 Boron nitride 1 Coupled lasers 1 Cryogenics 1 Crystals 1 Deterioration 1 Fiber coupled 1 Fracture toughness 1 Fundamental research 1 III-V semiconductors 1 Laser cooling 1 Laser-cooled 1 Lows-temperatures 1 Molybdenum oxide 1 Multi-pass 1 Nitrides 1 Optical cooling 1 Phonon polaritons 1 Phonons 1 Photons 1 Polarization-maintaining fiber 1 Polarization-maintaining optical fiber 1 Research fields 1 Scanning near-field optical microscopy 1 Single mode 1 Surface phonon-polaritons 1 Tapping modes 1