E.I. Ackerman

University of Cyprus, Lefkoşa, Lefkosia, Cyprus

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Publications (64)43.49 Total impact

  • Charles H. Cox, E.I. Ackerman
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    ABSTRACT: In this paper, we present a new type of photonic interface that is capable of conveying a receive signal from an antenna while simultaneously conveying a transmit signal to the same antenna. We call this interface a TIPRx, which is short for transmit-isolating photonic receiver. We first present the TIPRx theory of operation, and then focus on the key figures of merit: the degree of suppression of the transmit signal at the receive port, which is known as the transmit-to-receive (Tx/Rx) isolation, and the bandwidth over which this isolation is achieved. For a TIPRx using a conventionally designed Mach–Zehnder modulator that has a constant interaction between the modulator electrodes and the optical waveguides, we find that the Tx/Rx isolation has a sin$(x)$ /$x$ response. We then show that the Tx/Rx isolation can be significantly enhanced, at only a modest decrease in receive noise figure, by tapering the interaction between the modulator electrodes and optical waveguides. Finally, we report on experimental results of some TIPRx prototypes, which have achieved better than −30 dB of Tx/Rx isolation from 2.5–20 GHz and better than −40 dB from roughly 10–20 GHz.
    Journal of Lightwave Technology 10/2014; 32(20):3630-3636. DOI:10.1109/JLT.2014.2315783 · 2.86 Impact Factor
  • C.H. Cox, E.I. Ackerman
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    ABSTRACT: Communications and sensor systems on aircraft and other vehicles would benefit from the development of optical fiber links with low noise figure and high dynamic range over broad bandwidths extending to as high as 100 GHz. To date, however, there have been few reports of analog optical links that include their performance at f > 20 GHz, and the best unamplified noise figure [1] and dynamic range [2] results have been reported at ≤12 GHz. In this paper, we compare several competing link architectures, identify the one with the potential to yield high performance across a broad bandwidth up to 100 GHz, and discuss some of the challenges that must be overcome.
    Avionics, Fiber-Optics and Photonics Conference (AVFOP), 2013 IEEE; 01/2013
  • Charles H. Cox, Edward I. Ackerman
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    ABSTRACT: form only given, as follows. Simultaneous transmit and receive (STAR) capability is enabled by the recent development of a transmit-isolating photonic receive (TIPRx) link that functions both as the first-stage LNA in the receive front end and as an RF circulator, enabling a bidirectional interface to an antenna while isolating the receive chain from the transmit signal by 40 dB over bandwidths spanning multiple decades. This paper describes the TIPRx and issues involved in implementing a single-aperture STAR system.
    IEEE MTT-S International Microwave Symposium digest. IEEE MTT-S International Microwave Symposium 06/2011; DOI:10.1109/MWSYM.2011.5973433
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    C.H. Cox, E.I. Ackerman
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    ABSTRACT: We describe a new type of photonic link that replaces the low noise amplifier and circulator of conventional RF front ends, but has >; 20 dB greater isolation and >; 1000 times broader bandwidth.
    Optical Fiber Communication Conference and Exposition (OFC/NFOEC), 2011 and the National Fiber Optic Engineers Conference; 01/2011
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    C.H. Cox, E.I. Ackerman
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    ABSTRACT: In the last several years, there have been significant advances in photonics for phased arrays. In this paper we present results in two key areas: 1) For receive-only arrays, we report on improvements in analog fiber links that have resulted in new records for the intrinsic noise figure - i.e. noise figure without any RF amplification - of less than 6 dB at 12 GHz and SFDR of 120 dB in a 1 Hz bandwidth; 2) For arrays that both transmit and receive, we report on a new type of link we call TIPRx, for transmit-isolating photonic receive link. This new type of link has significantly better T/R isolation than a ferrite circulator, and over a much wider bandwidth. It also has gain like an LNA and low noise figure. Hence a single TIPRx link is the functional equivalent of several individual RF components.
    Phased Array Systems and Technology (ARRAY), 2010 IEEE International Symposium on; 11/2010
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    E.I. Ackerman, C.H. Cox
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    ABSTRACT: Previous publications have described techniques that various researchers at photonic systems, Inc. and elsewhere have used to optimize the performance of analog photonic links. The success of these efforts has made the incorporation of antenna-remoting photonic links into radars and RF communications systems attractive to the designers of such systems. In this paper we show that the simple addition of photonic links to carry signals to and from an RF transmit/receive (Tx/Rx) module, while straightforward, is often not the most beneficial approach because it unnecessarily subjects the inherently broadband photonic components to the same bandwidth limitations as the RF circuitry in the module. If one instead begins with the idea that the broadband photonics technology should be central to the design of the antenna Tx/Rx interface, a completely new architecture emerges - one that not only has greater capabilities than the conventional RF interface, but is simpler as well. As an example of a photonics-based antenna interface design that is simple and yields improved capabilities, we present a Tx-isolating photonic Rx (TIPRX) link that operates over many octaves or even decades of bandwidth while providing 40 dB or more of isolation between the transmit and receive signals. The potential system impact of the TIPRX is that an antenna can receive low-power signals while simultaneously transmitting much higher-power signals.
    Microwave Photonics, 2009. MWP '09. International Topical Meeting on; 11/2009
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    ABSTRACT: Using optical fiber to retrieve signals from remote sensors has several advantages compared to remoting by means of metallic waveguides such as coaxial cable. Fiber-optic retrieval of an RF signal can be achieved by down-converting and digitizing the signal for conveyance by a digital fiber-optic link, or it can be achieved by conveying the RF signal over an analog fiber-optic link before digitization. The latter approach can be realized with a minimum of hardware and dc power required at the sensing site, provided that the analog fiber-optic link has a sufficiently low noise figure without a pre-amplifier. Early demonstrations of ldquoamplifierlessrdquo analog fiber-optic links typically reported very high noise figures-in excess of 30 dB. In the last decade or so, several techniques have been developed to improve this situation. We describe five such techniques and show that they have resulted in much lower measured noise figures for amplifierless links. One technique, for example, has yielded noise figures < 5 dB for amplifierless links at frequencies of up to 10 GHz. The existence of amplifierless links with such low noise figures may enable remote sensing of signals in situations where the size, weight, and power (SWAP) of the remote hardware is of primary concern.
    Sarnoff Symposium, 2009. SARNOFF '09. IEEE; 05/2009
  • Edward I. Ackerman, Charles H. Cox
    Microwave Photonics: Devices and Applications, 04/2009: pages 131 - 167; , ISBN: 9780470744857
  • Charles H. Cox, E.I. Ackerman
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    ABSTRACT: In this paper we highlight some of the notable advances in microwave photonics over the last ~45 years and present some speculations about where we may go in the future. Some personal reminiscences are also included.
    Microwave photonics, 2008. jointly held with the 2008 asia-pacific microwave photonics conference. mwp/apmp 2008. international topical meeting on; 11/2008
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    ABSTRACT: Previously published analytical models for the noise figure of an amplifierless fiber-optic link fail to predict the measured performance, with a discrepancy of 1.1 dB at 1 GHz that increases to 2.3 dB by 12 GHz. We use an equivalent circuit to derive the effect of an additional source of noise not accounted for in earlier models: thermal noise arising from loss in the modulator's traveling-wave electrodes. The electrode thermal noise has a frequency dependence matching that of the link's noise figure, such that predictions using the improved model match the measured 1-12 GHz performance of a link with record low noise figure to within ~ 0.4 dB across this band.
    Journal of Lightwave Technology 09/2008; 26(15-26):2441 - 2448. DOI:10.1109/JLT.2008.927610 · 2.86 Impact Factor
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    E.I. Ackerman, C.H. Cox
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    ABSTRACT: We review reports of microwave photonic links with gain >0 dB in the absence of electronic amplifiers, and their corresponding noise figures.
    Lasers and Electro-Optics Society, 2007. LEOS 2007. The 20th Annual Meeting of the IEEE; 11/2007
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    ABSTRACT: We present a broad-bandwidth (1 -12 GHz) low-biased external modulation fiber-optic link without preamplifiers that has a gain of 6 dB-14 dB and a noise figure of < 7.S dB everywhere in this broad bandwidth, with a record low noise figure of only 3.4 dB at 2 GHz. The third-order distortion-limited spurious-free dynamic range (SFDK) of this link within any suboctavc portion of the 1-12 GHz range of operating frequencies is approximately 120 dBHz<sup>2/3</sup> in a 1-Hz instantaneous receiver bandwidth. We describe the high-performance components in this link and discuss the extent to which their performance varies with frequency, and show which of these components' frequency-dependent parameters affect which of the three figures of merit (gain, noise figure, and SFDR).
    Microwave Photonics, 2007 IEEE International Topical Meeting on; 11/2007
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    ABSTRACT: We demonstrate two analog photonic links that use different noise reduction techniques to achieve high gain and low noise figure without electronic amplification. Both links use a high-power, low-noise master oscillator power amplifier as the optical source, a balanced-bridge dual-output LiNbO<sub>3</sub> Mach-Zehnder modulator with a record low V<sub>pi</sub> = 1.33 V at 12 GHz, and either one or two high-power rear-illuminated photodetectors. In the first link, both outputs of the quadrature-biased modulator are used to illuminate two photodetectors configured for laser noise cancellation, yielding record high gain (> 17.0 dB) and low noise figure (< 6.9 dB) across the 6-12 GHz band. The second link uses low biasing to maximize the signal-to-noise ratio in one of the two modulator outputs, and thus requires only one photo-detector. This link has lower gain (> 12.7 dB) but also record low noise figure (< 5.7 dB) across this same frequency band.
    Microwave Symposium, 2007. IEEE/MTT-S International; 07/2007
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    ABSTRACT: The authors correct an error in their original article (see ibid., vol.54, no.2, p.906-20, Feb. 2006)
    IEEE Transactions on Microwave Theory and Techniques 03/2007; 55(2-55):351 - 351. DOI:10.1109/TMTT.2006.890072 · 2.94 Impact Factor
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    ABSTRACT: Photonic Systems, Inc. pursued the goal stated in the RF Lightwave Integrate Circuits' (RFLIC's) BAA ("...achieving a Vpi in the range of 0.1 to 0.5 Volts [to enable a link having] zero RF insertion loss with 1 - 10 mW of optical power available from conventional laser diode sources") on two parallel development paths. Collaborating with Sarnoff Corporation, Photonic Systems developed a Bipolar Cascade Laser that achieved a slope efficiency of 0.5 W/A by forcing the link's input RF signal to feed a series-connected succession of multiple laser junctions whose optical outputs are collected in parallel to illuminate the link's single photodetector. Additionally, Photonic Systems developed a Broad Bandwidth Resonant Modulator, in which two low-loss optical resonators act as a lever to reduce the effective Vpi by 25% for a Vpi=2.7V of the interferometric optical intensity modulator process relative to the Vpi of the optical phase modulator embedded within the two resonators.
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    ABSTRACT: This paper is divided into two major parts. Following a brief introduction that establishes some definitions and assumptions, Section II updates our earlier study on the limits of the RF performance of optical links. Section III reviews progress since our 1997 review paper in the development of devices enabling link performance closer to these limits, including (but not limited to): 1) cascade lasers that permit broad-band direct modulation links with gain >0 dB; 2) injection-locked edge- and surface-emitting lasers at 1300 and 1550 nm with modulation frequency responses as great as 40 GHz; 3) modulators with improved performance, especially electroabsorption modulators that now have switching voltages as low as 0.36 V, or handle optical powers as great as 60 mW, or have bandwidths as great as 50 GHz (but not all three of these in one device yet); and 4) high-speed photodetectors with high saturation currents, e.g., a 20-GHz device with a saturation current of 90 mA and a 55-GHz device with saturation at 50 mA. We conclude in Section IV by summarizing the component developments necessary for higher performance RF-over-fiber links, i.e.: 1) semiconductor lasers (for direct modulation) that have higher slope efficiency and bandwidth and lower relative intensity noise (RIN) at reasonable bias current levels; 2) continuous wave (CW) lasers (for external modulation) with higher fiber-coupled power and lower RIN; 3) higher frequency lower loss external modulators with more linear transfer functions and lower V<sub>π</sub> that can withstand larger CW optical powers; and 4) photodetectors with higher responsivity and bandwidth that respond linearly even when illuminated by greater average optical powers.
    IEEE Transactions on Microwave Theory and Techniques 03/2006; DOI:10.1109/TMTT.2005.863818 · 2.94 Impact Factor
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    ABSTRACT: We report achieving a record low noise figure for an amplifierless fiber-optic link — ≤ 15 dB over the frequency range 1.0 – 9.5 GHz — via a combination of a low-V π Mach-Zehnder modulator with two antiphase outputs, a high-power laser, and a balanced photodetector pair. We also present a complete model for this link that predicts its measured performance to within 1 dB.
    Microwave Photonics, 2005. MWP 2005. International Topical Meeting on; 11/2005
  • C.H. Cox III, E.I. Ackerman, G.E. Betts
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    ABSTRACT: The loss of coax, even moderately high frequencies, can be so high as to rule out many important applications. Lower loss means RF transmission exist, such as waveguides, but the size and weight of such options severely restrict the applications. In this paper, the authors review the conditions under which an optical link can achieve positive gain, as measured by the available power gain. This paper also reviews the link design factors that permit the link to have low noise figure and show that there is a fundamental dependence link gain and noise figure.
    Avionics Fiber-Optics and Photonics, 2005. IEEE Conference; 10/2005
  • J.L. Prince, E.I. Ackerman, C.H. Cox III
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    ABSTRACT: Analog photonic components can be used to overcome the electronic bandwidth limitations in backplane, intra-board, and intra-chip applications. The components of an analog optical link are shown. In order for analog photonic components to be practical and appropriate for optical interconnects, methods have been developed to improve the gain, noise figure, and spurious free dynamic range, the figures of merit of a photonic link is defined. Understanding the link design tradeoffs and the performance of the individual components allows the design engineer to develop a photonic system with optimal performance. The state-of-the-art photonic link performance is demonstrated. During this presentation approaches to improve link performance will be reviewed.
    Biophotonics/Optical Interconnects and VLSI Photonics/WBM Microcavities, 2004 Digest of the LEOS Summer Topical Meetings; 07/2004
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    Charles H. Cox, Edward I. Ackerman
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    ABSTRACT: To achieve gain ≥0 dB in an external modulation analogue optical link with modest laser power (10 mW), the external modulator needs to have an on−off voltage (Vπ) of 0.3 V, which is more than a factor of 10 smaller than the on−off voltages of most commercially available modulators. Polymeric materials, in which the electrooptic tensor r33 has been engineered to have a very large magnitude (>100 pm/V), enable external modulator designers to meet this goal, because the modulator's on−off voltage is inversely proportional to this tensor magnitude. Now that polymer materials have surpassed 100 pm/V, the natural question is: what do we need even higher r33 material for? We will show that there are many uses to which a larger r33 material can be put, but that, contrary to present perception, even lower Vπ is not one of them. The paper concludes by discussing one of the uses for a larger r33: a linearized modulator.
    The Journal of Physical Chemistry B 06/2004; 108(25):8540-8542. DOI:10.1021/jp036854y · 3.38 Impact Factor

Publication Stats

996 Citations
43.49 Total Impact Points

Institutions

  • 2009
    • University of Cyprus
      • Department of Electrical and Computer Engineering
      Lefkoşa, Lefkosia, Cyprus
  • 1996–2000
    • Massachusetts Institute of Technology
      • Department of Electrical Engineering and Computer Science
      Cambridge, Massachusetts, United States
  • 1997
    • Drexel University
      • Department of Electrical and Computer Engineering
      Philadelphia, Pennsylvania, United States
  • 1994
    • Martin Marietta Laboratories
      Baltimore, Maryland, United States