Abstract

Recently, the introduction of Fourier Domain Mode Locking (FDML) [1] has helped to overcome physical limitations of the sweep repetition rate of rapidly wavelength swept laser sources [2]. Such sources can be applied for optical coherence tomography (OCT) [3] using frequency domain detection [4]. This technique is called swept source OCT (ss-OCT) or optical frequency domain imaging (OFDI). FDML lasers consist of a laser gain medium (SOA), an output coupler, a periodically driven optical band-pass filter (FFP-TF) and an optical delay line, so that their total length is typically several kilometres (Fig 1a). For stable laser operation, the frequency of the optical band pass filter must be synchronized to the optical roundtrip frequency of the light in the cavity. In this paper we systematically study the influence of chromatic dispersion caused by the long delay fibre. In our setup, we can switch between two cavities with different amount of dispersion by exchanging a spool of standard fibre (SMF) with a spool of dispersion compensation fibre (DCF).

© 2009 IEEE