Improving repetition rates and tuning capabilities of liquid crystal lasers

Liquid crystal lasers (LCLs) are currently a prominent area of interest in photonics research. Their low-cost, ease of fabrication, self-assembling structure, high efficiencies (some up to 60%) and compact size make LCLs an appealing alternative to larger more expensive tunable systems [1]. There are, however, still several technological hurdles to overcome before viable commercialisation can be achieved.

One such issue is the current limitation of repetition rate. Above a certain pump repetition rate of ~100 Hz, the liquid crystal laser begins to lose efficiency due to optically and thermally induced instabilities [2]. Here we present the highest repetition rates yet achieved. A liquid crystal laser cell was mounted on a disk spinning at a step frequency of 10 kHz and enabled laser pumping at 10 kHz. This minimised energy degradation over time and yielded an average output power of ~3 mW [3].

Multi-wavelength tuning was achieved by mounting cells, each filled with dye-doped liquid crystals of different chiralities, around the circumference of the disk. Twenty different wavelengths were obtained with a rotation rate of 15 Hz and an effective pump frequency of 5 Hz.