Font Size: a A A

Development Of Swept Laser Source For Optical Coherence Tomography

Posted on:2012-04-17Degree:DoctorType:Dissertation
Country:ChinaCandidate:M H ChenFull Text:PDF
GTID:1118330371457774Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Optical coherence tomography (OCT) is a micrometer-resolution imaging technique that produces cross-sectional images of sample microstructure by measuring the amplitude and echo time delay of backscattered light. In this dissertation, the research is focused on development of high performance swept laser source which is the key technique of real-time optical coherence tomography imaging. Three different tuning filters design are proposed, four sets of swept laser source based on different methods are developed. Implementing the laser source in optical frequency domain imaging system, real-time and high resolution structural imaging of biological tissue is demonstrated. The main work and innovations are summarized as follows:1. All-fiber ring-cavity wavelength swept laser source based on fiber Fabry-Perot tunable filter is demonstrated. The developed laser source provides up to 8,000 sweeps per second over a full-width wavelength tuning range of 120 nm, full width at half maximum of 65 nm at center wavelength of 1320 nm.3 dB bandwidth of the instantaneous linewidth is about 0.08 nm and average power is 9 mW. All-fiber swept laser is compact, portable and easy to maintenance.2. Implementing the all-fiber Fabry-Perot tunable filter based swept laser source in optical frequency domain imaging system, the axial resolution is 13.6μm (in air), the axial range is 3.4 mm (in air) and maximum sensitivity is about 112 dB. Real-time in vivo structural imaging of biological tissue and scattering medium is obtained. For optimization consideration based on this custom-built swept laser, experimental study on imaging quality relevant parameters of the swept laser with sine and ramp driving waveforms to the FFP-TF is conducted, and investigation of the repetition rate and output power on the cavity length is done.3. A broad-band high-speed short-cavity swept laser source based on grating & polygon mirror tunable filter is reported. Center wavelength of the developed swept laser source is 1312 nm with a turning range of 170 nm and 3dB bandwidth of 116 nm. A repetition frequency up to 50 kHz with an average output power of 2 mW is realized. In order to facilitate the filtering system, the tunable filter consists of polygon scanner and grating in Littrow telescope-less configuration. Parallel implementation of two semiconductor optical amplifiers with different wavelength range is adopted in the laser resonator for broad-band light amplification.4. A Fourier domain mode locking (FDML) long-cavity linearized swept laser source is presented. The laser resonator includes gain medium, tunable filter and delay line. Serial implementation of two semiconductor optical amplifiers is adopted in the laser for gain amplification. The tunable speed of the FDML swept laser centered at 1290 nm is 14.8 kHz with an average output power of 3 mW. The turning range is 108 nm with 3dB bandwidth of 61 nm.5. A novel broad tunable bandwidth and narrow instantaneous line-width linear swept laser source using combined tunable filter is proposed. The combined filter consist of a fiber Fabry-Perot tunable filter working at the non-resonant frequency and a tunable filter based on diffractive grating with scanning polygon mirror. The trade-off between bandwidth and instantaneous line-width is alleviated. The swept laser working at 1290 nm center wavelength provides a tuning range of 180 nm with 3dB line-width of about 114 nm at sweeping rate of 23.3 kHz. The instantaneous linewidth can be reach to 0.03 nm and output power is 3 mW.
Keywords/Search Tags:optical coherence tomography, optical frequency domain imaging, swept laser source, fiber Fabry-Perot tunable filter, grating/polygon mirror tunable filter, Fourier domain mode locking, combined tunable filter
PDF Full Text Request
Related items