Using a discrete thermal model to obtain a linear frequency ramping in a frequency-modulated continuous-wave system

Daniel Nordin; Kalevi Hyyppae

doi:10.1117/1.1949205

1 July 2005 Using a discrete thermal model to obtain a linear frequency ramping in a frequency-modulated continuous-wave system

Daniel Nordin, Kalevi Hyyppae

Author Affiliations +

Optical Engineering, Vol. 44, Issue 7, 074202 (July 2005). https://doi.org/10.1117/1.1949205

Abstract

The lasing wavelength of a single-section distributed feedback (DFB) laser diode can be modulated by modulating the drive current. This makes it possible to utilize the DFB laser diode in a frequency-modulated continuous wave (FMCW) range and velocity measuring system. In FMCW, the frequency of the laser is ramped, and the frequency difference between the reflected wave and a local-oscillator wave is monitored. For maximum performance the frequency ramping should be linear. Due to thermal phenomena, a linear ramping of the current seldom results in a linear ramping of the optical frequency. We have derived a discrete thermal model, using resistors and capacitors, of our laser module. The thermal model was then used as a starting point to model the frequency behavior of the laser and to derive modulation currents that resulted in a linear frequency ramping at some different modulation frequencies.

©(2005) Society of Photo-Optical Instrumentation Engineers (SPIE)

Citation Download Citation

Daniel Nordin and Kalevi Hyyppae "Using a discrete thermal model to obtain a linear frequency ramping in a frequency-modulated continuous-wave system," Optical Engineering 44(7), 074202 (1 July 2005). https://doi.org/10.1117/1.1949205

Published: 1 July 2005

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