Chi Nan

A high-speed bi-directional visible light communication system based on RGB-LED

In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats (QAM-OFDM), advanced digital signal processing, pre- and post-equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes (LEDs), of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios (BERs) for all channels after 0.7 m indoor delivery are below pre-forward-error-correction (pre-FEC) threshold of 3.8×103. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.

A flexible optical packet compression and routing scheme by using an active vertical coupler-based optical crosspoint switch matrix [Topics in Optical Communications]

We experimentally demonstrate all-optical packet compression for an RZ payload up to 40 Gb/s and a label at 155 Mb/s, based on a recirculating buffer with one individual optical crosspoint switch. The packet can be flexibly switched, dropped, time slot interchanged up to 9 time slots, and compressed up to 4 packets in one time slot. Back-to-back BER performance of the 4 times compressed packet was measured with only 1.8 dB of power penalty. By using variable fiber delay lines, this scheme can be further extended to applications for variable length/time slot packet routing and compression.

A Novel Scheme to Generate Terahertz Signal over Fiber Based on Dual-Stage Single Side Band Modulation

A dual stage optical single side band ( DSSB) modulation scheme to combat chromatic dispersion for the terahertz over fiber ( ToF) systems application is proposed. In the scheme, terahertz wave is obtained via carrier suppression double sideband (DSB) modulation, one sideband of terahertz wave then undergo the fisrt single sideband ( SSB) modulation and the second baseband SSB modulation in the process of data modulation, which achieves cascade SSB modulation. As can ben seen from the sumulation result, for mid frequency carrier of 0. 1 THz, the bit error rate ( BER) performance without dispersion compensation achives 1 10 11 and the sensitivit y of the receiver is 26. 6 dBm with a data rate of 5 Gb/ s after 100 km transmission. Through comparing the power penalty of DSB and DSSB, we demonstrated the optical SSB modulation has better dispersion tolerance. This paper also shows the contrastive curves of frequency selective fading for the SSB and DSB modulated signals, which definitely demonstrates the existence of dispersion fading during the DSB transmission as well as the effective suppression of the fading implemented by the SSB modulation. The novel scheme s preferences is excelled than the conventional scheme s, which is demonstrated by these theory and simulation.