The Experts below are selected from a list of 6537 Experts worldwide ranked by ideXlab platform

Mohsen Kavehrad - One of the best experts on this subject based on the ideXlab platform.

  • Holographic parabolic mirror as a receiver Optical Front End for wireless infrared communications: experimental study.
    Applied optics, 2002
    Co-Authors: S. Jivkova, Stanislav Shurulinkov, Mohsen Kavehrad
    Abstract:

    The inherent multifunctionality of holographic Optical elements and their light physical weight make them an attractive solution for the receiver optics of portable terminals in indoor infrared wireless communication systems. A parabolic holographic mirror has been recorded in silver halide at a visible wavelength, and its replay wavelength has been shifted to the near infrared. Employment of proprietary swelling technology resulted in a permanent replay wavelength shift without the need for hologram sealing. Despite the relatively low diffraction efficiency of holograms recorded in silver halide in principle, an improvement in the receiver signal-to-noise ratio of more than 20 dB has been measured. The results of the conducted experiments proved undoubtedly the great potential of curved holographic mirrors as a key element of the receiver Optical Front End in IR wireless communication systems.

  • receiver designs and channel characterization for multi spot high bit rate wireless infrared communications
    IEEE Transactions on Communications, 2001
    Co-Authors: S. Jivkova, Mohsen Kavehrad
    Abstract:

    This paper addresses one of the most promising candidates for high-speed in-house wireless communications, namely, the multi-spot diffusing configuration (MSDC). Since it uses the Optical infrared medium for data transmission, it has the inherent potential for achieving very high capacities. The channel characteristics in MSDC are simulated and the causes for channel distortion are analyzed. Then, conditions for creation of a virtually ideal channel are derived. It is shown that the 3-dB channel bandwidth can be extEnded up to beyond 2 GHz. This bandwidth comes at the cost of a poor power efficiency. In order to compensate for that, a novel receiver Optical Front-End design is proposed and its performance is analyzed. Taking advantage of the unique properties of the holographic Optical elements, the conventional Optical Front-End, consisting of a concentrator and a filter, is replaced by a single holographic curved mirror. The utilization of such a holographic Optical element improves the signal-to-shot noise ratio by up to 18.5 dB.

Jri Lee - One of the best experts on this subject based on the ideXlab platform.

  • 4 25 gb s transceiver with Optical Front End for 100 gbe system in 65 nm cmos technology
    IEEE Journal of Solid-state Circuits, 2015
    Co-Authors: Pingchuan Chiang, Jhihyu Jiang, Haowei Hung, Chinyang Wu, Gaunsing Chen, Jri Lee
    Abstract:

    This paper presents a fully-integrated chipset for 4×25 Gb/s transceiver gearbox along with laser driver and photo detector Front-Ends. The transceiver provides 10:4 multiplexing and 4:10 demultiplexing conversion, with built-in clock generation, equalization, and amplification. The Optical Front-Ends are realized as 4-element arrays, presenting remarkable performance with commercial vertical-cavity surface-emitting lasers and photodiodes. Feedforward equalizers and continuous-time linear equalizers are employed to compensate for loss and distortion in both electrical and Optical domains. Fabricated in 65 nm CMOS technology, these chips can be lumped together as a compact module with performance exceeding typical 100 GbE standards.

Theodore J Schmidt - One of the best experts on this subject based on the ideXlab platform.

  • design of coherent receiver Optical Front End for unamplified applications
    Optics Express, 2012
    Co-Authors: Bo Zhang, Christian Malouin, Theodore J Schmidt
    Abstract:

    Advanced modulation schemes together with coherent detection and digital signal processing has enabled the next generation high-bandwidth Optical communication systems. One of the key advantages of coherent detection is its superior receiver sensitivity compared to direct detection receivers due to the gain provided by the local oscillator (LO). In unamplified applications, such as metro and edge networks, the ultimate receiver sensitivity is dictated by the amount of shot noise, thermal noise, and the residual beating of the local oscillator with relative intensity noise (LO-RIN). We show that the best sensitivity is achieved when the thermal noise is balanced with the residual LO-RIN beat noise, which results in an optimum LO power. The impact of thermal noise from the transimpedance amplifier (TIA), the RIN from the LO, and the common mode rejection ratio (CMRR) from a balanced photodiode are individually analyzed via analytical models and compared to numerical simulations. The analytical model results match well with those of the numerical simulations, providing a simplified method to quantify the impact of receiver design tradeoffs. For a practical 100Gb/s integrated coherent receiver with 7% FEC overhead, we show that an optimum receiver sensitivity of −33dBm can be achieved at GFEC cliff of 8.55E-5 if the LO power is optimized at 11dBm. We also discuss a potential method to monitor the imperfections of a balanced and integrated coherent receiver.

Benn C Thomsen - One of the best experts on this subject based on the ideXlab platform.

  • design of a 1 tb s superchannel coherent receiver
    Journal of Lightwave Technology, 2016
    Co-Authors: David S Millar, Domanic Lavery, Robert Maher, Toshiaki Koikeakino, Milutin Pajovic, Alex Alvarado, Milen Paskov, Keisuke Kojima, Kieran Parsons, Benn C Thomsen
    Abstract:

    We describe the design of a trained and pilot-aided digital coherent receiver, capable of detecting a 1 Tb/s superchannel with a single Optical Front-End. Algorithms for receiver training are described, which calculate the equalizer coefficients, subchannel SNRs, and centroids of the transmitted constellations. Algorithms for pilot-aided operation are then described in detail, providing pilot-aided constant modulus equalization and joint carrier-phase estimation over several coherent subchannels. We demonstrate the detection of a superchannel with net bit rate in excess of 1 Tb/s with a single coherent receiver. An $11\times 10$  GBd DP-64QAM Nyquist superchannel is used, with 1.32 Tb/s gross bit rate.

Deog-kyoon Jeong - One of the best experts on this subject based on the ideXlab platform.

  • A 22 to 26.5 Gb/s Optical Receiver With All-Digital Clock and Data Recovery in a 65 nm CMOS Process
    IEEE Journal of Solid-State Circuits, 2015
    Co-Authors: Gyu-seob Jeong, Sungchun Jang, Deog-kyoon Jeong
    Abstract:

    This paper presents a 22 to 26.5 Gb/s Optical receiver with an all-digital clock and data recovery (AD-CDR) fabricated in a 65 nm CMOS process. The receiver consists of an Optical Front-End and a half-rate bang-bang clock and data recovery circuit. The Optical Front-End achieves low power consumption by using inverter-based amplifiers and realizes sufficient bandwidth by applying several bandwidth extension techniques. In addition, in order to minimize additional jitter at the Front-End, not only magnitude and bandwidth but also group-delay responses are considered. The AD-CDR employs an LC quadrature digitally controlled oscillator (LC-QDCO) to achieve a high phase noise figure-of-merit at tens of gigahertz. The recovered clock jitter is 1.28 ps rms and the measured jitter tolerance exceeds the tolerance mask specified in IEEE 802.3ba. The receiver sensitivity is 106 and 184 for a bit error rate of 10-12 at data rates of 25 and 26.5 Gb/s, respectively. The entire receiver chip occupies an active die area of 0.75 mm2 and consumes 254 mW at a data rate of 26.5 Gb/s. The energy efficiencies of the Front-End and entire receiver at 26.5 Gb/s are 1.35 and 9.58 pJ/bit, respectively.