We have proposed and experimentally demonstrated a novel scheme to generate optical millimeter-wave (mm-wave) signals by using single-sideband modulation with low-frequency local oscillator (LO) ...signals. In this architecture, by incorporating the proper dc bias of the modulator in central office, the optical mm-wave carriers are generated with two times frequency of the LO signal while largely reducing the bandwidth requirement of the modulator. We quantify the optical carrier-to-sideband ratio (CSR) of downstream transmission in this radio-over-fiber (ROF) link and establish that the performance of the ROF system can be significantly improved when the optical signals are transmitted at CSR equal to 0 dB.
Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with ...higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation formats is challenging. Electrical Nyquist pulse generation is restricted by the limited sampling rate and processor capacities of digital-to-analog convertor devices, while the optical Nyquist signals can provide a much higher symbol rate using time domain multiplexing method. However, most optical Nyquist signals are based on direct detection with simple modulation formats. Here we report the first experimental demonstration of high speed all optical Nyquist signal generation based on Sinc-shaped pulse generation and time-division multiplexing with high level modulation format and full-band coherent detection. Our experiments demonstrate a highly flexible and compatible all optical high speed Nyquist signal generation and detection scheme for future fiber communication systems.
Multiple myeloma (MM) is the second most common hematologic malignancy. Despite recent treatment advances, it remains incurable. Here, we report that Pim2 kinase expression is highly elevated in MM ...cells and demonstrate that it is required for MM cell proliferation. Functional interference of Pim2 activity either by short hairpin RNAs or by a potent and selective small-molecule inhibitor leads to significant inhibition of MM cell proliferation. Pim inhibition results in a significant decrease of mammalian target of rapamycin C1 (mTOR-C1) activity, which is critical for cell proliferation. We identify TSC2, a negative regulator of mTOR-C1, as a novel Pim2 substrate and show that Pim2 directly phosphorylates TSC2 on Ser-1798 and relieves the suppression of TSC2 on mTOR-C1. These findings support Pim2 as a promising therapeutic target for MM and define a novel Pim2-TSC2-mTOR-C1 pathway that drives MM proliferation.
•Pim2 expression is highly elevated in multiple myeloma and is required for multiple myeloma proliferation.•Pim2 phosphorylates TSC2 and modulates mTOR-C1 activity to promote multiple myeloma cell proliferation.
In this paper, we experimentally compared the performance of discrete-Fourier-transform spread (DFT-spread) and pre-equalization in a 244.2-Gb/s polarization-division-multiplexed 16-ary quadrature ...amplitude-modulation orthogonal frequency-division multiplexing (PDM-16QAM-OFDM) transmission system. The pre-equalization is effective to overcome the high-frequency power attenuation in the channel. However, the acquisition of static channel response for pre-equalization is really complicated and the peak-to-average power ratio (PAPR) of the signal after pre-equalization even becomes a little higher. The DFT-spread can be applied to simultaneously resist high-frequency power attenuation and reduce the PAPR of OFDM signal. The experimental results also show that one band DFT-spread demonstrates the best narrow optical filtering tolerance. The transmission distance for 8 × 244.2-Gb/s wavelength-division-multiplexing (WDM) PDM-16QAM-OFDM at the soft-decision forward-error correction threshold of 2.4×10 -2 is 2× 420 km based on pre-equalization, while extended to over 3×420 km based on one band DFT-spread, which well illustrates one band DFT-spread is more efficient for high-bandwidth coherent WDM-OFDM system.
Filter-bank multicarrier (FBMC) is proposed to demonstrate a full-duplex asynchronous quasi-gapless (only one subcarrier spacing) carrier aggregation for millimeter-wave (MMW) radio-over-fiber radio ...access technology (RAT) in next-generation 5G heterogeneous mobile-data-network (Het-Net). Fourteen broadband FBMC signals are aggregated with only one subcarrier guard band in the 60-GHz MMW downlink. In the uplink quasi-gapless asynchronous inter-RAT carrier aggregation between 60-GHz MMW and 4G long-term evolution (LTE) signals are also demonstrated. System performances assessment of FBMC and orthogonal frequency-division multiplexing (OFDM) under different operation condition are studied. Our results also show that the FBMC-based new RAT is also backward compatible with existing LTE systems in the Het-Net. Compared with OFDM-based signals with large guard bands, FBMC achieves higher spectral efficiency with better error vector magnitude performance at less received power and smaller guard bands.
The phase and amplitude precoding technique is essential in optical carrier suppression-based photonic constant-and multi-amplitude quadrature-amplitude-modulation vector signal generation at radio ...frequency bands. In this letter, a novel precoding scheme with constellations balanced distribution is proposed and investigated. We experimentally demonstrate 8-GBd quadrature-phase-shift-keying (QPSK) vector signal generation at 16 GHz enabled by a single Mach-Zehnder modulator-based oscilloscope modulation and the proposed precoding scheme. Compared with imbalanced precoding, this scheme can provide 2-dB receiver sensitivity improvement, and the obtained constellations at the receiver end is much more symmetrical, which represents the in-phase (I) and quadrature (Q) components have equal performance. The bit-error-ratio for 8-GBd QPSK vector signals can be under hard-decision forward-error-correction threshold of 3.8×10 -3 after a 25-km standard single-mode fiber transmission.
We propose and experimentally demonstrate vector signals seamless integration delivery over fiber-THz-fiber link. Up to 13 Gb/s quadrature-phase-shift-keying signals are transmitted over 10 km single ...mode fiber-28 (SMF-28), 3.8 m wireless link, and 2.2 km SMF-28 link. At the transmitter, we use a photonics-aided scheme to generate 450 GHz THz signal. While at the receiver side, we employ analog down-conversion by one electrical mixer, and then the down-converted signals are used to drive one directly modulated laser to realize electrical-to-optical conversion.
A new optical millimeter-wave generation scheme to double the beating frequency without suppressing the carrier by taking advantages of the out-of-phase property between sidebands of a ...phase-modulated optical carrier is proposed for the first time. Theoretical analysis shows that the generated 60 GHz optical millimeter-wave (mm-wave) can tolerant ±0.016 nm wavelength drifting with filter bandwidth ranging from 70 to 100 GHz to sustain first to second harmonic suppression ratio of 18 dB. The doubled frequency is continuously tunable from 60 to 90 GHz within 100 GHz filter bandwidth with RF power variation of less than 2 dB. In addition, simultaneously generating and transmitting multi-band signal: millimeter-wave band, microwave band, and baseband leveraging the same concept is also proposed. Error-free transmission of 2.5 Gb/s wireless baseband signals carried by the generated 60 GHz mm-wave is successfully demonstrated in both single- and multi-band network environments over a combined optical fiber and wireless distance with a proper equivalent isotropically radiated power of about 20 dBm for in-building access. Moreover, dispersion effect on the generated frequency-doubled optical mm-wave is analyzed by experimentally comparing the link performance of both single mode fiber (SMF-28) and dispersion-shifted fiber cases. It is concluded that for single-band service delivery, the proposed scheme is immune to the interference from the dispersion-induced, redundant 1st harmonics; however, to deliver multi-band services, launching lightwave at zero-dispersion wavelength over SMF-28 is highly recommended to mitigate inter-band interference.
Terahertz band (0.1 to 10 THz) with high carrier frequency and large available bandwidth has become a promising candidate to meet the 100 Gbit/s or even 1 Tbit/s data rate required by the future ...six-generation (6G) mobile communication networks. Compared with the all-electrical methods to generate terahertz signals, the photon-assisted technology can break the bottleneck of the bandwidth limit of the electronics devices, and generate the terahertz signal with high frequency, large bandwidth, flexible tunability and easy integration with the large capacity fiber link. In this paper, we introduce the typical methods to generate terahertz signals based on the photon-assisted technology, and review the representative achievements in different areas of terahertz communication, such as the large capacity terahertz transmission, the long distance terahertz transmission, the real-time terahertz communication, and the integrated terahertz sensing and communication. Based on the photon-assisted technology and various key techniques, devices and advanced digital signal processing (DSP) algorithms, we have obtained many great achievements in broadband terahertz communication and sensing, and the experimental setups and results have also been demonstrated in detail.
We propose W-band photonic millimeter-wave (mm-wave) vector signal generation employing a precoding-assisted random frequency tripling scheme enabled by a single phase modulator cascaded with a ...wavelength selective switch (WSS). The selected two optical subcarriers from the phase modulator output by the WSS can have several different kinds of combinations with asymmetrical orders, such as (−3, 0), (−2, 1), (−1, 2), and (0, 3). Employing our proposed precoding-assisted random frequency tripling scheme, we experimentally demonstrate 1/2-Gbd 81-GHz quadrature-phase-shift-keying (QPSK) mm-wave vector signal generation and its wireless delivery over 0.5-m air space distance. We also experimentally demonstrate that the generated mm-wave vector signal based on the minus second-order (−2nd) and first-order (1st) subcarriers, which is equivalent to that based on the minus first-order (−1st) and second-order (2nd) subcarriers, has a better bit-error-ratio (BER) performance than that based on the minus third-order (−3rd) and central (0th) subcarriers, which is equivalent to that based on the 0th and third-order (−3rd) subcarriers, when the phase modulator has a relatively small driving radio-frequency (RF) voltage, whereas an opposite result occurs when the phase modulator has a relatively large driving RF voltage, which is consistent with both our theoretical analysis and numerical simulation.
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