First CEO beat frequency directly from a 1.5-µm Er:Yb:glass laser oscillator

The authors have demonstrated the first CEO frequency detection from a 1.5-mum laser without amplification or compression. The result is a free running CEO beat frequency with an excellent 49-dB SNR and 17-times improvement in linewidth compared to other sources available in this wavelength range. Implementing stabilization with a PLL is straight forward. Further noise reduction can be expected in the near future by improving the packaged laser design, also an increase of the repetition rate into the GHz regime is anticipated.