A distributed fiber sensor based on Rayleigh scattering is described which converts vibration-induced optical phase changes into optical intensity variations by using modulated dual-pulses injected into sensing fiber. Phase generated carrier algorithm is used to permit arctangent operation to demodulate the phase information along the sensing fiber. The demonstrated sensor is capable of probing dynamic acoustic or vibration disturbances over 10km of sensing length with spatial resolution of 6m and large signal to noise ratio. The background noise of our system is estimated about 1×10<sup>-3</sup> rad/√Hz.
We fabricated a narrow linewidth 1.55μm directly-modulated distributed-feedback (DFB) laser. The laser exhibits an
output power of 14mW at 100mA, flat frequency response with -3 dB bandwidth of 18 GHz, the third-order
intermodulation distortion (IMD3) with 39.8dBm, narrow optical linewidth with 181kHz, and RIN below -135.7dB/Hz
in the 0.1-10GHz range along with the high side-mode suppression ratio (<52dB). We also experimentally verified the
modulation bandwidth, linearity, and linewidth is related to the bias current. The characteristics of the laser, namely
sufficient modulation bandwidth, high linearity, low relative intensity noise (RIN) and narrow linewidth, make it the
perfect candidates for high dynamic directly modulated analog optical link.
An ultra wideband optical frequency comb (OFC) generator based on semiconductor Quantum dot F-P cavity is packaged by our group. The free spectral rage (FSR) of the OFC can be tunable from 97GHz to 100GHz and the pulse width of the 100GHz OFC is 1.2ps.The full span of the OFC spectra is 80nm with a Gaussian shaped, and in span of 10nm, the flatness of the OFC can be limited to 1.7dB. The OFC has the advantages of small volume, simple and compact structure, low power dissipation, and has an ultra-wide bandwidth and flat spectrum, which can be used in the field of arbitrary waveform generation, channel information processing, and optical frequency division multiplexing.