In this paper, hybrid optical delay line (HODL) which is demanded on automotive radar test system (RTS) is proposed and demonstrated. HODL is composed with coaxial cable in short delay time (< 32 nsec) and optical fiber in long delay time (≥ 32 nsec) which are considering the volume, loss and frequency characteristics. Also, the optical transceiver that has the bandwidth of 1 GHz is designed for frequency modulated continuous wave (FMCW). Experimental results show that the S21 is ± 0.5 dB in the optical transceiver and ± 1.7 dB in the whole system at 3.7 GHz ~ 4.7 GHz. The resolution of delay time is 1 ns and the delay flatness is ± 0.23 ns.
Surface plasmon resonance (SPR) sensor has been studied for high sensitivity optical biosensor as a single molecule
detection, virus detection, DNA sequencing etc. SPR sensor requires an ultra-small signal detection system that measures
very small intensity variation of reflected light along with the change of a refractive index near the sensor surface. In this
reason, lock-in detection method which is able to detect small signal buried in noise has been applied to SPR sensor. In
general lock-in detection method using multiplier and low pass filter measures DC value of output, and its sensitivity is
determined by 1/f noise at DC. Unlike the DC measurement we have proposed 2ω harmonic lock-in detection method
using multiplier and band pass filter. Sensitivity of the proposed lock-in detection method is much lower than 1/f noise at
DC. In this paper we will show that 2ω harmonic lock-in detection method for SPR sensor system providing the
In this paper, we propose a simple and efficient predistortion method using schottky diodes to compensate the nonlinearity of RoF systems. L-I curve in LD is compared with I-V curve in schottky diode and the nonlinear characteristics are analyzed. The predistortion circuit has been designed with two paths. One path is the nonlinearity generation circuit with schottky diode, while the other path has only a time delay. Then, these two paths are recombined to suppress the IMD3 (3rd inter - modulation distortion) of LD. Experimental results show that the enhancements of about 26 dBc in the IMD3 and about 8.5 dB in the SFDR are achieved at 2.4 GHz.