Filtered ASE swept source for OCT medical imaging
View Patent ↗An integrated swept wavelength optical source uses a filtered ASE signal with an optical amplifier and tracking filter. This source comprises a micro optical bench, a source for generating broadband light, a first tunable Fabry Perot filter, installed on the bench, for spectrally filtering the broadband light from the broadband source to generate a narrowband tunable signal, an amplifier, installed on the bench, for amplifying the tunable signal, and a second tunable Fabry Perot filter, installed on the bench, for spectrally filtering the amplified tunable signal from the amplifier. A self-tracking arrangement is also possible where a single tunable filter both generates the narrowband signal and spectrally filters the amplified signal. In some examples, two-stage amplification is provided. The use of a single bench implementation yields a low cost high performance system. For example, polarization control between components is no longer necessary.
1. A wavelength swept optical source, comprising:
an amplified spontaneous emission source for generating broadband light;
a tunable Fabry Perot filter for spectrally filtering the broadband light from the amplified spontaneous emission source to generate a tunable signal;
a polarization beam splitter for transmitting the broadband light to the tunable Fabry Perot filter from the amplified spontaneous emission source;
a polarization rotation system downstream of the polarization beam splitter for rotating the polarization;
a semiconductor optical amplifier for amplifying the tunable signal with the amplified tunable signal being transmitted back through the tunable Fabry-Perot filter for a double pass arrangement to yield a self-tracking configuration and then through the polarization beam splitter, which provides the amplified tunable signal as an output signal and avoids coupling of the amplified tunable signal to the source or back through the semiconductor amplifier to avoid creation of a resonant cavity.
2. A wavelength swept optical source as claimed in claim 1 , wherein the polarization rotation system comprises a Faraday rotator.
3. A wavelength swept optical source as claimed in claim 1 , wherein semiconductor optical amplifier is a semiconductor optical amplifier with a reflective facet.