Improved Optical Heterodyne Methods for Measuring Frequency Responses of Photodetectors

An electrical-filtered optical heterodyne technique for tuning speed measurement of DBR lasers

“…To confirm the accuracy of the method proposed in Figure 1, another scheme using an optical filter proposed in [8] was carried out for the same tunable DBR laser under the same tuning period, with the experimental setup shown in Figure 7. In this method, a fiber Bragg grating (JDSU TB9) was used as an optical filter with a full width at half maximum (FWHM) 30 GHz bandwidth.…”

“…Comparing the electrical-filtered optical heterodyne technique with other methods [5][6][7][8][9][10], the optical heterodyne technique has the advantages that the choice of the electrical filter is much more arbitrary and the stability of the electrical filter is superior. A tunable optical filter is not necessary and the problems of the instability of the optical filters can be avoided.…”

“…A timeresolved spectrum technique based on a scanning FabryPérot interferometer was successfully used in wavelength switching measurements on SG-DBR lasers [5,6]. In [7,8], an optical filter was needed to filter out the lightwave in a certain channel, and the optical filter was required to have a tunable central wavelength and good stability. In [9], the authors tracked the wavelength switching behavior of a tunable laser by analyzing the low-frequency beat signal in the time-frequency domain based on a self-heterodyne method.…”

Effects of the electrical signals generated in passive sections of SG-DBR lasers

“…The wavelength variation is inconspicuous when the applied voltage is below 600 mV and has a mode-hopping when the voltage is around 900 mV. Although directly applying voltage instead of current to the phase section has many merits, such as easy for modulation [9], it is the injected carriers that change the inner refraction index and tune the wavelength [5]. Hence, the current in the circuit was also measured and the results are shown in Fig.…”

Frequency drift and instantaneous linewidth broadening of phase-section tuned SG-DBR laser

“…In recent years, tunable semiconductor lasers, such as distributed Bragg reflector (DBR) lasers, evoke great interests [1][2][3][4][5]. Microwave generation using optical heterodyne method is a promising subject in testing and sensing field.…”