In the modern intelligent fiber Bragg grating (FBG) sensing network, the spectrum interrogation should not only have high speed and wavelength resolution, but also use the limited spectrum resource efficiently. In this paper, we propose a spectrum interrogation technique by using a wavelength-division multiplexing (WDM) to optical time-division multiplexing (OTDM) converter, which could map the sensing signals from the wavelength domain to the time domain quickly and efficiently. The converter consists of an electro-optic switch, time delay unit and a multi-wavelength converter. The continuous WDM sensing signals are converted into pulsed WDM signals by using a 10 GHz LiNbO<sub>3</sub> intensity modulator as the electro-optic switch. A segment of single mode fiber (SMF) is used as the time delay unit for delaying the pulsed WDM signals overlapped in time. By using a high speed 40 GHz electro-absorption modulator (EAM) as the multi-wavelength converter, the pulsed and delayed WDM signals are converted into OTDM signals with the same wavelength. At last, the light signals after demodulation are detected by photoelectric detector (PD) which has high response speed and low cost. The mapping of the wavelength domain to the time domain in our spectrum interrogation can allocate the spectrum resource efficiently and dynamically. It is experimentally demonstrated that two signals in wavelength domain can be converted into time domain signals carried by a wavelength with a roughly equal conversion efficiency.
In this paper, we propose a scheme on precisely tunable L-band multi-wavelength fiber laser. This fiber laser has two
main characteristics namely broad wavelength band, uniform power spectrum and precise electronic tunability. About 65 wavelengths output within ± 1.5dB power variation with 50GHz channel spacing in broad spectrum range can be obtained at room temperature. The measured optical signal noise ratio (OSNR) and line width of each wavelength are about 20dB and 345.5MHz respectively. Theses 65 wavelengths are able to be tuned simultaneously up or down in frequency domain with a tuning step ranging from 10 MHz to 14 GHz. The tuning resolution can potentially be as low as 1 Hz in our experiment.