New rapidly wavelength-swept light sources for optical coherence tomography and picosecond pulse generation

摘要: This thesis deals with research on novel, semiconductor-based, ultrafast and widely tunable wavelength-swept light sources respect to different applications. The main focus was the young technology of Fourier domain mode locked (FDML) lasers, where insertion a kilometer-long fiber delay line enables tune narrowband spectral filter synchronously roundtrip time in resonator. In this way, very high sweep speeds become feasible. A successful application field biomedical imaging is optical coherence tomography (OCT), FDML lasers allow for large image acquisition rates. One important part work development characterization novel concepts improving performance applicability OCT. context, two modes operation have been demonstrated. On one hand, an laser highly linear time-frequency characteristic realized first allowed OCT at 1300 nm based simplified numerical processing. other subharmonic implemented successfully used nm. Here, passes same several times during each cavity roundtrip. case reduced range, enabled inherent multiplication effective rate by factor ten, reaching 570 kHz. Another achievement demonstration new type sources, superluminescent alternately cascade gain elements filters which be tuned out phase order compensate transit light. Different implementations operated 1060 rates up 340 Ultrafast human retina shown. second focused investigation approach short pulse generation, within wavelength sweeps temporally compressed subsequent pass through 15 km dispersive fiber. achievable temporal width indicator properties quality mode-locking laser. became evident critical dependence frequency as well due results comparable generation experiments using incoherent source. With dispersion compensated laser, 1560 nm, durations 60-70 ps repetition 390 kHz were achieved. Although bandwidth-limited pulses not feasible, it shown that electric must least partially coherent. Due remaining uncompensated higher chirp, bandwidth limited 6 energy restricted. Pulse energies 5.6 nJ achieved erbium-doped amplification prior compression.