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A Time Difference Method for Measurement of Phase Shift between Distributed Feedback Laser Diode (DFB-LD) Output Wavelength and Intensity.

Liu Y, Chang J, Lian J, Liu Z, Wang Q, Zhu C - Sensors (Basel) (2015)

Bottom Line: This approach takes advantage of asymmetric absorption positions at the same wavelength during wavelength increase and decrease tuning processes in the intensity-time curve by current modulation.The phase shifts at modulation frequencies ranging from 50 Hz to 50 kHz were measured with a resolution of 0.001π.As the modulation frequency increased the shift value increased with a slowed growth rate.

View Article: PubMed Central - PubMed

Affiliation: School of Information Science and Engineering, Shandong University, Jinan 250100, China. Liuyongning1990@163.com.

ABSTRACT
A time difference method to conveniently measure the phase shift between output wavelength and intensity of distributed feedback laser diodes (DFB-LDs) was proposed. This approach takes advantage of asymmetric absorption positions at the same wavelength during wavelength increase and decrease tuning processes in the intensity-time curve by current modulation. For its practical implementation, a measurement example of phase shift was demonstrated by measuring a time difference between the first time and the second time attendances of the same gas absorption line in the intensity-time curve during one sine or triangle modulation circle. The phase shifts at modulation frequencies ranging from 50 Hz to 50 kHz were measured with a resolution of 0.001π. As the modulation frequency increased the shift value increased with a slowed growth rate.

No MeSH data available.


(a) Time shift of triangle wave modulation (black square) and sine wave modulation (red dot) at modulation frequencies from 50 Hz to 50 kHz; (b) Phase shift of triangle wave modulation (black square) and sine wave modulation (red dot) at modulation frequencies from 50 Hz to 50 kHz. All the axes are logarithmically scaled.
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sensors-15-16153-f004: (a) Time shift of triangle wave modulation (black square) and sine wave modulation (red dot) at modulation frequencies from 50 Hz to 50 kHz; (b) Phase shift of triangle wave modulation (black square) and sine wave modulation (red dot) at modulation frequencies from 50 Hz to 50 kHz. All the axes are logarithmically scaled.

Mentions: On the transmitted intensity-time curve, the absorption caused by the 1368.6-nm absorption line happened at different positions in the same modulation step, and the experiment data shown that as modulation frequency increased the phase shifts between output wavelength and intensity increased as well. Based on the above system and conditions, phase shifts between output intensity and wavelength were measured at modulation frequencies from 50 Hz to 50 kHz. For 1 kHz modulation, shift values were 0.1π and 0.091π, respectively, for the triangle wave and sine wave with a resolution of 0.001π. More measurement results are detailed in Figure 4. For both modulation waveforms, phase shifts increased with a slowed growth rate as modulation frequency increased. Shift value of triangle wave modulation was a little greater than that of sine wave at the same modulation frequency, shown in Figure 4b. This disparity should be on account of two reasons, one is the individual response of DFB-LD to the different current change rates of triangle and sine wave modulation forms, the other is the fact that triangle wave contains harmonics (fundamental frequency and its multiple frequencies) and the phase shift increases with frequency.


A Time Difference Method for Measurement of Phase Shift between Distributed Feedback Laser Diode (DFB-LD) Output Wavelength and Intensity.

Liu Y, Chang J, Lian J, Liu Z, Wang Q, Zhu C - Sensors (Basel) (2015)

(a) Time shift of triangle wave modulation (black square) and sine wave modulation (red dot) at modulation frequencies from 50 Hz to 50 kHz; (b) Phase shift of triangle wave modulation (black square) and sine wave modulation (red dot) at modulation frequencies from 50 Hz to 50 kHz. All the axes are logarithmically scaled.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541872&req=5

sensors-15-16153-f004: (a) Time shift of triangle wave modulation (black square) and sine wave modulation (red dot) at modulation frequencies from 50 Hz to 50 kHz; (b) Phase shift of triangle wave modulation (black square) and sine wave modulation (red dot) at modulation frequencies from 50 Hz to 50 kHz. All the axes are logarithmically scaled.
Mentions: On the transmitted intensity-time curve, the absorption caused by the 1368.6-nm absorption line happened at different positions in the same modulation step, and the experiment data shown that as modulation frequency increased the phase shifts between output wavelength and intensity increased as well. Based on the above system and conditions, phase shifts between output intensity and wavelength were measured at modulation frequencies from 50 Hz to 50 kHz. For 1 kHz modulation, shift values were 0.1π and 0.091π, respectively, for the triangle wave and sine wave with a resolution of 0.001π. More measurement results are detailed in Figure 4. For both modulation waveforms, phase shifts increased with a slowed growth rate as modulation frequency increased. Shift value of triangle wave modulation was a little greater than that of sine wave at the same modulation frequency, shown in Figure 4b. This disparity should be on account of two reasons, one is the individual response of DFB-LD to the different current change rates of triangle and sine wave modulation forms, the other is the fact that triangle wave contains harmonics (fundamental frequency and its multiple frequencies) and the phase shift increases with frequency.

Bottom Line: This approach takes advantage of asymmetric absorption positions at the same wavelength during wavelength increase and decrease tuning processes in the intensity-time curve by current modulation.The phase shifts at modulation frequencies ranging from 50 Hz to 50 kHz were measured with a resolution of 0.001π.As the modulation frequency increased the shift value increased with a slowed growth rate.

View Article: PubMed Central - PubMed

Affiliation: School of Information Science and Engineering, Shandong University, Jinan 250100, China. Liuyongning1990@163.com.

ABSTRACT
A time difference method to conveniently measure the phase shift between output wavelength and intensity of distributed feedback laser diodes (DFB-LDs) was proposed. This approach takes advantage of asymmetric absorption positions at the same wavelength during wavelength increase and decrease tuning processes in the intensity-time curve by current modulation. For its practical implementation, a measurement example of phase shift was demonstrated by measuring a time difference between the first time and the second time attendances of the same gas absorption line in the intensity-time curve during one sine or triangle modulation circle. The phase shifts at modulation frequencies ranging from 50 Hz to 50 kHz were measured with a resolution of 0.001π. As the modulation frequency increased the shift value increased with a slowed growth rate.

No MeSH data available.