Nonlinear frequency chirp measurement of frequency sweeping lasers for FD-OCT applications

Tae Jung Ahn, Dug Young Kim

Research output: Contribution to journalConference article

1 Citation (Scopus)

Abstract

A noble measurement method by using a homodyne interferometer and Hilbert transform has been proposed for characterizing frequency sweeping light sources used in traditional optical frequency domain reflectometer (OFDR) and optical frequency domain imaging (OFDI). A Michelson interferometer with a tunable laser generates a sinusoidal beating signal. A phase of measured beating signal as a function of time is approximately proportional to optical frequency of the swept light source during frequency tuning and can be obtained by the Hilbert transformation. Thus, optical frequency chirp can be determined by a simple equation related with the phase of the beating signal from the interferometer. We have demonstrated the effectiveness and the simplicity of our proposed method by testing a temperature-tuned frequency sweeping DFB-LD and a commercial external cavity tunable laser source as practical examples. In the case of DFB-LD, the frequency sweep becomes more linear while the amount of frequency sweep saturates as the amplitude of the control voltage applied to a TEC driver increases, and the frequency-tuning rate increases as the repetition rate decreases. We also found that a commercial frequency-sweeping laser has a feed back control to adjust its frequency-sweeping rate such that the tuning rate oscillates around an intended value as a function of time. We have demonstrated the possibility of using a self-homodyne interferometer as a powerful tool for characterizing frequency sweeping laser sources. We expect this method will be useful for improving the performance of many optical frequency domain measurement techniques such as OFDR, FD-OCT or OFDI.

Original languageEnglish
Article number61081A
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume6108
DOIs
Publication statusPublished - 2006 May 1
EventCommercial and Biomedical Applications of Ultrafast Lasers VI - San Jose, CA, United States
Duration: 2006 Jan 172006 Jan 19

Fingerprint

Sweeping
Chirp
chirp
Interferometers
Laser tuning
Reflectometers
Tuning
Laser
Light sources
Lasers
lasers
Imaging techniques
Michelson interferometers
Frequency Domain
Voltage control
Feedback control
Sweep
Interferometer
Tunable Laser
Testing

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Cite this

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abstract = "A noble measurement method by using a homodyne interferometer and Hilbert transform has been proposed for characterizing frequency sweeping light sources used in traditional optical frequency domain reflectometer (OFDR) and optical frequency domain imaging (OFDI). A Michelson interferometer with a tunable laser generates a sinusoidal beating signal. A phase of measured beating signal as a function of time is approximately proportional to optical frequency of the swept light source during frequency tuning and can be obtained by the Hilbert transformation. Thus, optical frequency chirp can be determined by a simple equation related with the phase of the beating signal from the interferometer. We have demonstrated the effectiveness and the simplicity of our proposed method by testing a temperature-tuned frequency sweeping DFB-LD and a commercial external cavity tunable laser source as practical examples. In the case of DFB-LD, the frequency sweep becomes more linear while the amount of frequency sweep saturates as the amplitude of the control voltage applied to a TEC driver increases, and the frequency-tuning rate increases as the repetition rate decreases. We also found that a commercial frequency-sweeping laser has a feed back control to adjust its frequency-sweeping rate such that the tuning rate oscillates around an intended value as a function of time. We have demonstrated the possibility of using a self-homodyne interferometer as a powerful tool for characterizing frequency sweeping laser sources. We expect this method will be useful for improving the performance of many optical frequency domain measurement techniques such as OFDR, FD-OCT or OFDI.",
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