Fast optical frequency sweep for ultra-fine real-time spectral domain measurement

2006 ◽  
Vol 42 (17) ◽  
pp. 999 ◽  
Author(s):  
T. Kawanishi ◽  
T. Sakamoto ◽  
M. Izutsu
Keyword(s):  
Real Time ◽  
Spectral Domain ◽  
Optical Frequency ◽  
Frequency Sweep

scholarly journals THz Signal Generator Using a Single DFB Laser Diode and the Unbalanced Optical Fiber Interferometer

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4862
Author(s):  
Blaž Pongrac ◽  
Denis Đonlagic ◽  
Matej Njegovec ◽  
Dušan Gleich
Keyword(s):  
Optical Fiber ◽  
Laser Diode ◽  
Optical Signal ◽  
Optical Path Difference ◽  
Sweep Rate ◽  
Path Difference ◽  
Optical Path ◽  
Signal Generator ◽  
Optical Frequency ◽  
Frequency Sweep

This paper presents a frequency-modulated optical signal generator in the THz band. The proposed method is based on a fast optical frequency sweep of a single narrowband laser diode used together with an optical fiber interferometer. The optical frequency sweep using a single laser diode is achieved by generating short current pulses with a high amplitude, which are driving the laser diode. Theoretical analysis showed that the modulation frequency could be changed by the optical path difference of the interferometer or optical frequency sweep rate of a laser diode. The efficiency of the optical signal generator with Michelson and Fabry–Perot interferometers is theoretically analyzed and experimentally evaluated for three different scenarios. Interferometers with different optical path differences and a fixed optical frequency sweep rate were used in the first scenario. Different optical frequency sweep rates and fixed optical path differences of the interferometers were used in the second scenario. This paper presents a method for optical chirp generation using a programmable current pulse waveform, which drives a laser diode to achieve nonlinear optical sweep with a fixed optical path difference of the interferometer. The experimental results showed that the proposed signals could be generated within a microwave (1–30 GHz) and THz band (0.1–0.3 THz).

Ambiguity-free spectral-domain optical coherence tomography for determining the layer thicknesses in fluttering foils in real time

2012 ◽  
Vol 50 (10) ◽  
pp. 1372-1376 ◽  
Author(s):  
Alexandra Nemeth ◽  
Robert Gahleitner ◽  
Günther Hannesschläger ◽  
Giselher Pfandler ◽  
Michael Leitner
Keyword(s):  
Optical Coherence Tomography ◽  
Real Time ◽  
Spectral Domain ◽  
Optical Coherence

scholarly journals Numerical-Sampling-Functionalized Real-Time Index Regulation for Direct k-Domain Calibration in Spectral Domain Optical Coherence Tomography

Electronics ◽  
2018 ◽  
Vol 7 (9) ◽  
pp. 182 ◽  
Author(s):  
Sangyeob Han ◽  
Oeon Kwon ◽  
Ruchire Wijesinghe ◽  
Pilun Kim ◽  
Unsang Jung ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Real Time ◽  
Spectral Domain ◽  
Optical Coherence ◽  
Axial Resolution ◽  
Dependent Signal ◽  
Nonlinear Sampling ◽  
Time Linear ◽  
Optical Laser ◽  
Sd Oct

An index-regulation technique functionalized by numerical sampling for direct calibration of the non-linear wavenumber (k)-domain to a linear domain in spectral domain optical coherence tomography (SD-OCT) is proposed. The objective of the developed method is to facilitate high-resolution identification of microstructures in biomedical imaging. Subjective optical alignments caused by nonlinear sampling of interferograms in the k-domain tend to hinder depth-dependent signal-to-noise ratios (SNR) and axial resolution in SD-OCT. Moreover, the optical-laser-dependent k-domain requires constant recalibrated in accordance with each laser transition, thereby necessitating either hardware or heavy software compensations. As the key feature of the proposed method, a relatively simple software-based k-domain mask calibration technique was developed to enable real-time linear sampling of k-domain interpolations whilst facilitating image observation through use of an index-regulation technique. Moreover, it has been confirmed that dispersion can be simultaneously compensated with noise residuals generated using the proposed technique, and that use of complex numerical or hardware techniques are no longer required. Observed results, such as fall-off, SNR, and axial resolution clearly exhibit the direct impact of the proposed technique, which could help investigators rapidly achieve optical-laser-independent high-quality SD-OCT images.

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