9 research outputs found

    Architectures for ku-band broadband airborne satellite communication antennas

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    This paper describes different architectures for a broadband antenna for satellite communication on aircraft. The antenna is a steerable (conformal) phased array antenna in Ku-band (receive-only). First the requirements for such a system are addressed. Subsequently a number of potential architectures are discussed in detail: a) an architecture with only optical true time delays, b) an architecture with optical phase shifters and optical true time delays and c) an architecture with optical true time delays and RF phase\ud shifters (or RF true time delays). The last two architectures use sub-arrays to reduce complexity of the antenna system. The advantages and disadvantages of the different architectures are evaluated and an optimal architecture is selected

    Novel ring resonator-based integrated photonic beamformer for broadband phased array receive antennas - part I: design and performance analysis

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    A novel optical beamformer concept is introduced that can be used for seamless control of the reception angle in broadband wireless receivers employing a large phased array antenna (PAA). The core of this beamformer is an optical beamforming network (OBFN), using ring resonator-based broadband delays, and coherent optical combining. The electro-optical conversion is performed by means of single-sideband suppressed carrier modulation, employing a common laser, Mach-Zehnder modulators, and a common optical sideband filter after the OBFN. The unmodulated laser signal is then re-injected in order to perform balanced coherent optical detection, for the opto-electrical conversion. This scheme minimizes the requirements on the complexity of the OBFN, and has potential for compact realization by means of full integration on chip. The impact of the optical beamformer concept on the performance of the full receiver system is analyzed, by modeling the combination of the PAA and the beamformer as an equivalent two-port RF system. The results are illustrated by a numerical example of a PAA receiver for satellite TV reception, showing that—when properly designed—the beamformer hardly affects the sensitivity of the receiver

    A broadband high dynamic range analog photonic link using push-pull directly-modulated semiconductor lasers

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    We demonstrate an analog photonic link with a high multioctave spurious-free dynamic range (SFDR) of 119 dBHz2/3. The link consists of a pair of semiconductor DFB lasers modulated in a push-pull manner and a balanced photodetector. With precise amplitude and phase matchings, a signal enhancement of 4.5 dB and a second-order intermodulation distortion suppression of 40 dB relative to the case of a single arm optical link with one laser can be achieved. To our knowledge, the measured SFDR is one of the highest broadband value ever achieved with directly modulated lasers. Index Terms—Intermodulation distortion, laser noise, optical modulation, semiconductor laser

    Seperate carrier tuning scheme for integrated optical delay lines in photonic beamformers

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    We implement and experimentally demonstrate the separate carrier tuning technique on an optical ring resonator-based integrated optical delay line. For the first time, the carrier tuner, the delay elements and the optical sideband filter are integrated on the same chip. The proposed approach allows to reduce the complexity of the delay unit and makes the bandwidth independent of the absolute RF frequency. The demonstrated principle can be conveniently employed in any integrated non-coherent optical beamformer system

    Dual-frequency distributed feedback laser with optical frequency locked loop for stable microwave signal generation

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    We demonstrate the photonic generation of microwave signals by using a dual-frequency distributed feedback waveguide laser in ytterbium-doped aluminum oxide (Al2O3:Yb3+). An optical frequency locked loop (OFLL) was implemented to stabilize the center frequency of the microwave signal. This approach resulted in a microwave frequency at ∌14 GHz with a phase noise of −75 dBc/Hz at 1 MHz offset from the center frequency. The frequency stability of the photonic microwave signal has an Allan deviation of more than 1×10−10 for an averaging time of 1000 s. The combination of the dualfrequency laser and the OFLL scheme holds great potential for the photonic generation and distribution of highly stable microwave or millimeter-wave signals

    Multi-wavelength integrated optical beamformer based on Wavelength division multiplexing for 2-D phased array antennas

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    A novel, hardware-compressive architecture for broadband and continuously tunable integrated optical truetime- delay beamformers for phased array antennas is proposed and experimentally demonstrated. The novel idea consists in employing the frequency-periodic response of optical ring resonator (ORR) filters in conjunction with on-chip wavelength division multiplexing (WDM), in order to create multiple signal paths on an individual beamformer channel. This novel idea dramatically reduces the network complexity and, in turn, its footprint on the wafer. This allows the integration of an unprecedented number of delay channels on a single chip, ultimately overcoming the main limitation of integrated optical beamformers, that is, the difficulty to feed antenna arrays with many elements using a single integrated chip. A novel beamformer has been realized based on this technique, using the ultra-low-loss TriPleXTM waveguide platform with CMOScompatible fabrication equipment, and its functionality is demonstrated over an instantaneous bandwidth from 2 to 10 GHz. This result, at the best of our knowledge, represents at the same time the record instantaneous bandwidth (8 GHz) for an optical beamformer based on optical ring resonators (ORR), and the first demonstration of an integrated beamformer where the periodic response of ORRs is exploited to process signals from different antenna elements, simultaneously, using a single delay line

    Novel ring resonator-based integrated photonic beamformer for broadband phased array receive antennas - part 2: experimental prototype: experimental prototype

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    An experimental prototype is presented that illustrates the implementation aspects and feasibility of the novel ring resonator-based optical beamformer concept that has been developed and analyzed in Part I of this paper . This concept can be used for seamless control of the reception angle in broadband wireless receivers employing a large phased array antenna (PAA). The design, fabrication, and characterization of a dedicated chip are described, in which an 8×\times1 optical beamforming network, an optical sideband filter for single-sideband suppressed carrier modulation, and a carrier re-insertion coupler for balanced optical detection are integrated. The chip was designed for satellite television reception using a broadband PAA, and was realized in a low-loss, CMOS-compatible optical waveguide technology. Tuning is performed thermo-optically, with a switching time of 1 ms. Group delay response and power response measurements show the correct operation of the OBFN and OSBF, respectively. Measurements on a complete beamformer prototype (including the electro-optical and opto-electrical conversions) demonstrate an optical sideband suppression of 25 dB, RF-to-RF delay generation up to 0.63 ns with a phase accuracy better than π\pi/10 radians, and coherent combining of four RF input signals, all in a frequency range of 1–2 GHz

    Silicon nitride microwave photonic circuits

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    We present an overview of several microwave photonic processing functionalities based on combinations of Mach-Zehnder and ring resonator filters using the high index contrast silicon nitride (TriPleXTM) waveguide technology. All functionalities are built using the same basic building blocks, namely straight waveguides, phase tuning elements and directional couplers. We recall previously shown measurements on high spurious free dynamic range microwave photonic (MWP) link, ultra-wideband pulse generation, instantaneous frequency measurements, Hilbert transformers, microwave polarization networks and demonstrate new measurements and functionalities on a 16 channel optical beamforming network and modulation format transformer as well as an outlook on future microwave photonic platform integration, which will lead to a significantly reduced footprint and thereby enables the path to commercially viable MWP system
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