Non-resonant wavelength modulation saturation spectroscopy in acetylene-filled hollow-core photonic bandgap fibres applied to modulationfree laser diode stabilisation

Abstract

In this paper the application of Wavelength Modulation (WM) techniques to non-resonant saturation spectroscopy in acetylene-filled Hollow-Core Photonic Bandgap Fibres (HC-PBFs) and m odulation-free Laser Diode (LD) frequency stabilisation is investi gated. In the first part WM techniques are applied to non-resonant pump-prob e saturation of acetylene overtone rotational transitions in a HC-P BF. A high-power DFB chip-on-carrier mounted LD is used in conjunction w ith a tuneable External Cavity Laser (ECL) and the main saturation paramete rs are characterized. In the second part a novel feedback system to stabiliz e the DFB emission wavelength based on the WM saturation results is im plemented. Modulation-free locking of the DFB laser frequency to the narrow linewidth saturation feature is achieved for both constant an d variable LD temperatures