摘要：We present a new and efficient method for the design of dispersive multilayer by employing a particle swarm optimization （PSO） technique. Its mathematical background is given and an adaptive PSO is realized with computer code. Two practical designing tasks are solved with this method, and the obtained results are competitive compared with other published structures. The adaptive PSO method demonstrates its merits of fast convergence and powerful global search ability, and could be used as a valuable tool for the optical thin film design.

摘要：Double-weight optical code division multiple access（OCDMA） systems are proposed for studying differentiated quality-of-service transmission. Based on quadratic congruence code（QCC）, we construct a one-dimensional double-weight code family, which can be well utilized in incoherent synchronous double-weight OCDMA networks. By introducing algebraic transformation to code sequences of QCC in level 1, we obtain multiple double-weight codes with cross-correlation 1. Under the same-bit-power assumption, the performance of low-weight codes can be significantly improved and is always superior to that of high-weight codes in double-weight OCDMA systems with power control. This property is contrary to previous conclusions under the same-chip-power assumption.

摘要：We present a modified method to design photonic crystal fibers (PCFs) with flattened dispersion char- acteristic. Using this modified PCF we design a broadband fiber optical parametric amplifier (FOPA), which provides a gain of 8 dB with 1.5-dB uniformity over a 260-nm bandwidth. Both the simulation results of total dispersion of PCF and the gain spectrum of FOPA are demonstrated.

摘要：Integrated diffractive optical mode converter, consisting of a diffractive optical element (DOE) and a slab waveguide, is used for fiber-to-waveguide coupling. The phase of the DOE is generally designed by optimization algorithm. In this paper, the precise design, a new method with one more restrictive way, is adopted to design the diffractive optical mode converter for fiber-to-waveguide coupling. Through this method, the intensity of any point on the output plane is fully filled with the required demand. Compared with what previously published, the coupling loss of the precise designed converter is lower.

摘要：A high speed inductorless limiting amplifier （LA） in an optical communication receiver with the work- ing speed up to 20 Gb/s is presented. The LA includes an input matching network, a four-stage 3rd order amplifier core, an output buffer for the test and a DC offset cancellation （DCOC）. It uses the active interleaving feedback technique both to broaden the bandwidth and achieve the flatness response. Based on our careful analysis of the DCOC and stability, an error amplifier is added to the DCOC loop in order to keep the offset voltage reasonable. Fabricated in the 65 nm CMOS technology, the LA only occupies an area of 0.45 × 0.25 mm2 （without PAD）. The measurement results show that the LA achieves a differential voltage gain of 37 dB, and a 3-dB bandwidth of 16.5 GHz. Up to 26.5 GHz, the Sddlm and Sdd22 are less than -16 dB and -9 dB. The chip excluding buffer is supplied by 1.2 V VDD and draws a current of 50 mA.

摘要：An OOK-NRZ visible light communication (VLC) system is designed by using a single white LED and a 550 nm visible photodetector. The emitting model of the single LED is established, and the general expression of the detector's output signals under OOK modulation is deduced. With the selected LED, detector and other related parameters, the designed communication system is optimized and its performance is analyzed. The optimized communication distance between the LED and the detector is 0.54 m at the communication bit rate of 1 Mbit/s. With the best communication distance, when the signal-to-noise ratio (SNR) is larger than 6.5 dB, the bit error rate (BER) can drop to 10-4. The analytical model and theory presented in this paper can be of certain practical meanings in the design of similar communication systems.

摘要：Considering that the white LED＇s spectral response decreases exponentially with the increase of carrier frequency for the on-off-keying non-return-to-zero （OOK-NRZ） visible light communication （VLC） data links, a fast-order RC high-pass filter isdesigned and fabricated as a post-equalizer （PE） to compensate the LED spectral response. Formulation and simu- lation are both available for illustrating the VLC performance with and without PE. Experiments are performed in detail for the fabricated OOK-NRZ VLC system integrated with PE. The data transmission results show that by using PE, the mea- sured carrier bandwidth is enhanced from 0.8 （0.4-1.2） MHz to 1.7 （0-1.7） MHz, and the bit-error-rate （BER） is less than 10^-9. It proves the feasibility of the proposed scheme in OOK-NRZ VLC data links.