Jinlong Yu

Design and implementation of a broadband optical rotary joint using C-lenses.

A broadband optical rotary joint (BORJ) was designed using C-lenses. Its insertion loss was less than 2 dB at both the 1300 nm and 1550 nm wavelength windows. Wavelength division multiplexing (WDM) technique was adopted to increase the number of data transmission channels. Hundreds of wavelength channels can be accommodated for data transmission through relatively rotating interfaces using this BORJ. The total data transmission rate through this BORJ can be more than 200 Gbit/s. By using Dove prism, both space division multiplexing (SDM) and WDM techniques can be implemented simultaneously in the design of BORJ with C-lenses. This structure of BORJ has a low cost. It can be used for optical data transmission and optical sensing.

4 × 160-Gbit/s multi-channel regeneration in a single fiber

Simultaneous regeneration of four high-speed (160 Gbit/s) wavelength-division multiplexed (WDM) and polarization-division multiplexed (PDM) signals in a single highly nonlinear fiber (HNLF) is demonstrated. The regeneration operation is based on four-wave mixing in HNLF, where the degraded data signals are applied as the pump. As a result, the noise on both 0 and 1 levels can be suppressed simultaneously in our scheme. The stimulated Brillouin scattering (SBS) from the continuous wave (CW) is suppressed by cross-phase modulation (XPM) from the data pump, relieving the requirement of external phase modulation of the CW light. Mitigation of the inter-channel nonlinearities is achieved mainly through an inter-channel 0.5 bit slot time delay. Bidirectional propagation is also applied to relieve the inter-channel four-wave mixing. The multi-channel regeneration performance is validated by bit-error rate (BER) measurements. The receiver powers at the BER of 10(-9) are improved by 1.9 dB, 1.8 dB, 1.6 dB and 1.5 dB for the four data channels, respectively.

THz photonic wireless links with 16-QAM modulation in the 375-450 GHz band.

We propose and experimentally demonstrate THz photonic wireless communication systems with 16-QAM modulation in the 375-450 GHz band. The overall throughput reaches as high as 80 Gbit/s by exploiting four THz channels with 5 Gbaud 16-QAM baseband modulation per channel. We create a coherent optical frequency comb (OFC) for photonic generation of multiple THz carriers based on photo-mixing in a uni-travelling carrier photodiode (UTC-PD). The OFC configuration also allows us to generate reconfigurable THz carriers with low phase noise. The multiple-channel THz radiation is received by using a Schottky mixer based electrical receiver after 0.5 m free-space wireless propagation. 2-channel (40 Gbit/s) and 4-channel (80 Gbit/s) THz photonic wireless links with 16-QAM modulation are reported in this paper, and the bit error rate (BER) performance for all channels in both cases is below the hard decision forward error correction (HD-FEC) threshold of 3.8e-3 with 7% overhead. In addition, we also successfully demonstrate hybrid photonic wireless transmission of 40 Gbit/s 16-QAM signal at carrier frequencies of 400 GHz and 425 GHz over 30 km standard single mode fiber (SSMF) between the optical baseband signal transmitter and the THz wireless transmitter with negligible induced power penalty.

THz Wireless Transmission Systems Based on Photonic Generation of Highly Pure Beat-Notes

In this paper, a terahertz (THz) wireless communication system at 400 GHz with various modulation formats [on-off keying (OOK), quadrature phase-shift keying (QPSK), 16-quadrature amplitude modulation (16-QAM), and 32-quadrature amplitude modulation (32-QAM)] is experimentally demonstrated based on photonic generation of highly pure THz carriers. The experimental THz wireless photonic transmission system is enabled by the ultrawideband behavior of an antenna-integrated unitraveling-carrier-photodiode-based transmitter and a Schottky mixer-based THz receiver. In the experiment, a phase-correlated optical frequency comb (OFC) is created for photomixing generation of the desired THz carrier frequencies with low phase noise. The OFC allows for the generation of flexibly tunable THz carrier frequencies. The performance of the generated THz carriers is experimentally characterized in terms of phase noise, spectrum purity, tunability, and long-term stability. In the case of generating 400 GHz carrier, the measured timing jitter, linewidth, and long-term stability in the experiment are 51.5 fs, less than 2 Hz, and less than ±1 Hz with 3 hours, respectively. We also theoretically analyze the phase noise of photonically generated THz beat-notes when phase correlation of two optical comb tones is damaged due to their path-length difference. In addition, we demonstrate THz wireless transmission of various modulation formats, including OOK, QPSK, 16-QAM, and 32-QAM at beyond 10 Gb/s in such a system, and the measured bit error rate (BER) performance for all the signals after 0.5 m free-space delivery is below the hard decision forward error correction threshold of 3.8 × 10-3. Furthermore, the influence of THz carrier purity on the system performance is experimentally analyzed with respect to the BER of the THz communication signals.

Simultaneous regeneration of 4×160-Gbit/s WDM and PDM channels in a single highly nonlinear fiber

We demonstrate simultaneous regeneration of 4×160-Gbit/s signals in a HNLF. The receiver powers at the BER of 10-9 are improved by 1.9 dB, 1.8 dB, 1.6 dB and 1.5 dB for the four channels, respectively.

120 Gb/s Multi-Channel THz Wireless Transmission and THz Receiver Performance Analysis

A photonic multi-channel terahertz (THz) wireless transmission system in the 350–475 GHz band is experimentally demonstrated. The employment of six THz carriers modulated with 10 Gbaud Nyquist quadrature phase-shift keying baseband signal per carrier results in an overall capacity of up to 120 Gb/s. The THz carriers with high-frequency stability and low phase noise are generated based on photonic photomixing of 25-GHz spaced six optical tones and a single optical local oscillator derived from a same optical frequency comb in an ultra-broadband uni-travelling carrier photodiode. The bit-error-rate performance below the hard decision forward error correction threshold of

Simultaneous regeneration of two 160 Gbit/s WDM channels in a single highly nonlinear fiber

3.8times 10^{mathrm {mathbf {-3}}}

0.4 THz Photonic-Wireless Link With 106 Gb/s Single Channel Bitrate

for all the channels is successfully achieved after wireless delivery. Furthermore, we also investigate the influence of the harmonic spurs in a THz receiver on the performance of transmission system, and the experimental results suggest more than 30 dB spur suppression ratio in downconverted intermediate frequency signals for obtaining less than 1 dB interference.

107 Gb/s RZ-DQPSK signal transmission over 108 km SMF using optical phase conjugation in an SOA

We experimentally demonstrate simultaneous all-optical regeneration of two 160 Gbit/s WDM channels in a single HNLF using fiber optical parametric amplification. Receiver sensitivities at a BER of 10-9 are improved by about 2.1 dB and 4.9 dB for the two channels, respectively. The BER is not degraded by the presence of a second channel.

80 Gbit/s 16-QAM Multicarrier THz Wireless Communication Link in the 400 GHz Band

To accommodate the demand of exponentially increased global wireless data traffic, the prospective data rates for wireless communication in the market place will soon reach 100xa0Gb/s and beyond. In the lab environment, wireless transmission throughput has been elevated to the level of over 100xa0Gb/s attributed to the development of photonic-assisted millimeter wave and terahertz (THz) technologies. However, most of recent demonstrations with over 100xa0Gb/s data rates are based on spatial or frequency division multiplexing techniques, resulting in increased systems complexity and energy consumption. Here, we experimentally demonstrate a single channel 0.4 THz photonic-wireless link achieving a net data rate of beyond 100xa0Gb/s by using a single pair of THz emitter and receiver, without employing any spatial/frequency division multiplexing techniques. The high throughput up to 106xa0Gb/s within a single THz channel is enabled by combining spectrally efficient modulation format, ultrabroadband THz transceiver and advanced digital signal processing routine. Besides that, our demonstration from system-wide implementation viewpoint also features high transmission stability, and hence shows its great potential to not only decrease the systems complexity, but also meet the requirements of prospective data rates for bandwidth-hungry short-range wireless applications.