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Super-homogenous saturation of microwave-photonic gain in optoeletronic oscillator systems

Published in:
IEEE Photonics J., Vol. 4, No. 5, October 2012, pp. 1256-1266.
Topic:

Summary

We show that the saturation characteristic of microwave-photonic gain is "superhomogeneous" such that the gain of a weaker tone saturates more rapidly than that of a stronger tone when both signals are transmitted over an intensity-modulated optical link. Using this gain model, we simulate the effect of nonlinear gain saturation on the performance of a slab-coupled optical waveguide (SCOW)-based optoelectronic oscillator (OEO). We verify our simulations with experimental measurements and show that low sidemode levels (< -110 dBc) can be achieved even when multiple modes can oscillate within the passband of the OEO loop filter.
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Summary

We show that the saturation characteristic of microwave-photonic gain is "superhomogeneous" such that the gain of a weaker tone saturates more rapidly than that of a stronger tone when both signals are transmitted over an intensity-modulated optical link. Using this gain model, we simulate the effect of nonlinear gain saturation...

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High dynamic range suppressed-bias microwave photonic links using unamplified semiconductor laser source

Published in:
AVFOP 2012: IEEE Avionics, Fiber-Optics and Photonics Tech. Conf., 11-13 September 2012, pp. 28-9.
Topic:
R&D group:

Summary

Microwave photonic (MWP) links with a low noise figure and high dynamic range are required for antenna remoting, radio-over-fiber (RoF), and other advanced applications. MWP links have recently been demonstrated with noise figures approaching 3 dB, without any electrical preamplification, by using low-noise high-power laser sources in conjunction with efficient optical intensity modulators and high-power photodetectors. An alternate approach to noise figure reduction, suitable for sub-octave links, is based on using a high-power laser source and shifting the bias point of an external optical intensity modulator to reduce the average photocurrent and suppress excess link noise. Here, we report the performance of a novel slab-coupled optical waveguide external-cavity laser (SCOWECL) in a suppressed bias MWP link. We compare the performance of this link with a suppressed-bias link using a source comprising a commercial-off-the-shelf (COTS) laser and erbium-doped fiber amplifier (EDFA) and show that MWP links built using SCOW-based emitter technology offer superior performance due to the small-form factor, high-efficiency, low-noise, and high power laser source.
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Summary

Microwave photonic (MWP) links with a low noise figure and high dynamic range are required for antenna remoting, radio-over-fiber (RoF), and other advanced applications. MWP links have recently been demonstrated with noise figures approaching 3 dB, without any electrical preamplification, by using low-noise high-power laser sources in conjunction with efficient...

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Impact of semiconductor optical amplifiers in coherent down-conversion microwave photonic links

Published in:
CLEO: Conf. on Lasers and Electro-Optics, 6-11 June 2012.
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R&D group:

Summary

We compare the impact of conventional semiconductor optical amplifiers (SOAs) and high linearity slab-coupled optical waveguide amplifiers (SCOWAs) on the SFDR of carrier-suppressed coherent down-conversion microwave photonic links.
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Summary

We compare the impact of conventional semiconductor optical amplifiers (SOAs) and high linearity slab-coupled optical waveguide amplifiers (SCOWAs) on the SFDR of carrier-suppressed coherent down-conversion microwave photonic links.

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Photonic ADC: overcoming the bottleneck of electronic jitter

Summary

Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy. Photonic ADCs, which perform sampling using ultra-stable optical pulse trains generated by mode-locked lasers, have been investigated for many years as a promising approach to overcome the jitter problem and bring ADC performance to new levels. This work demonstrates that the photonic approach can deliver on its promise by digitizing a 41 GHz signal with 7.0 effective bits using a photonic ADC built from discrete components. This accuracy corresponds to a timing jitter of 15 fs - a 4-5 times improvement over the performance of the best electronic ADCs which exist today. On the way towards an integrated photonic ADC, a silicon photonic chip with core photonic components was fabricated and used to digitize a 10 GHz signal with 3.5 effective bits. In these experiments, two wavelength channels were implemented, providing the overall sampling rate of 2.1 GSa/s. To show that photonic ADCs with larger channel counts are possible, a dual 20- channel silicon filter bank has been demonstrated.
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Summary

Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy...

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Compact external-cavity semiconductor mode-locked laser with quantum-well-intermixed modulator and saturable absorber

Summary

We demonstrate a slab-coupled optical waveguide external-cavity mode-locked laser having unique bandedges for the amplifier, modulator and saturable absorber elements. An average output power of 50mW and timing jitter of 254fs is achieved at 1.5-GHz.
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Summary

We demonstrate a slab-coupled optical waveguide external-cavity mode-locked laser having unique bandedges for the amplifier, modulator and saturable absorber elements. An average output power of 50mW and timing jitter of 254fs is achieved at 1.5-GHz.

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A photon-counting detector for exoplanet missions

Published in:
SPIE Vol. 8151, Techniques and Instrumentation for Detection of Exoplanets V, 5 September 2011, 81510K.

Summary

This paper summarizes progress of a project to develop and advance the maturity of photon-counting detectors for NASA exoplanet missions. The project, funded by NASA ROSES TDEM program, uses a 256x256 pixel silicon Geiger-mode avalanche photodiode (GM-APD) array, bump-bonded to a silicon readout circuit. Each pixel independently registers the arrival of a photon and can be reset and ready for another photon within 100 ns. The pixel has built-in circuitry for counting photo-generated events. The readout circuit is multiplexed to read out the photon arrival events. The signal chain is inherently digital, allowing for noiseless transmission over long distances. The detector always operates in photon counting mode and is thus not susceptible to excess noise factor that afflicts other technologies. The architecture should be able to operate with shot-noise-limited performance up to extremely high flux levels, >106 photons/second/pixel, and deliver maximum signal-to-noise ratios on the order of thousands for higher fluxes. Its performance is expected to be maintained at a high level throughout mission lifetime in the presence of the expected radiation dose.
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Summary

This paper summarizes progress of a project to develop and advance the maturity of photon-counting detectors for NASA exoplanet missions. The project, funded by NASA ROSES TDEM program, uses a 256x256 pixel silicon Geiger-mode avalanche photodiode (GM-APD) array, bump-bonded to a silicon readout circuit. Each pixel independently registers the arrival...

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Silicon single photon imaging detectors

Published in:
SPIE Vol. 8155, Infrared Sensors, Devices, and Applications; Single Photon Imaging II, 21 August 2011, 81551C.

Summary

Single-photon imaging detectors promise the ultimate in sensitivity by eliminating read noise. These devices could provide extraordinary benefits for photon-starved applications, e.g., imaging exoplanets, fast wavefront sensing, and probing the human body through transluminescence. Recent implementations are often in the form of sparse arrays that have less-than-unity fill factor. For imaging, fill factor is typically enhanced by using microlenses, at the expense of photometric and spatial information loss near the edges and corners of the pixels. Other challenges include afterpulsing and the potential for photon self-retriggering. Both effects produce spurious signal that can degrade the signal-to-noise ratio. This paper reviews development and potential application of single-photon-counting detectors, including highlights of initiatives in the Center for Detectors at the Rochester Institute of Technology and MIT Lincoln Laboratory. Current projects include single-photon-counting imaging detectors for the Thirty Meter Telescope, a future NASA terrestrial exoplanet mission, and imaging LIDAR detectors for planetary and Earth science space missions.
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Summary

Single-photon imaging detectors promise the ultimate in sensitivity by eliminating read noise. These devices could provide extraordinary benefits for photon-starved applications, e.g., imaging exoplanets, fast wavefront sensing, and probing the human body through transluminescence. Recent implementations are often in the form of sparse arrays that have less-than-unity fill factor. For...

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Thermally tuned dual 20-channel ring resonator filter bank in SOI (silicon-on-insulator)

Published in:
CLEO 2011, Conf. on Lasers and Electro-Optics, 1 May 2011.

Summary

Two 20-channel second-order optical filter banks have been fabricated. With tuning, the requirements for a wavelength multiplexed photonic AD-converter (insertion loss 1-3 dB, extinction >30 dB and optical bandwidth 22-27 GHz) are met.
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Summary

Two 20-channel second-order optical filter banks have been fabricated. With tuning, the requirements for a wavelength multiplexed photonic AD-converter (insertion loss 1-3 dB, extinction >30 dB and optical bandwidth 22-27 GHz) are met.

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MBE back-illuminated silicon Geiger-mode avalanche photodiodes for enhanced ultraviolet response

Published in:
SPIE Vol. 8033, Advanced Photon Counting Techniques V, 25 April 2011, 80330D.

Summary

We have demonstrated a wafer-scale back-illumination process for silicon Geiger-mode avalanche photodiode arrays using Molecular Beam Epitaxy (MBE) for backside passivation. Critical to this fabrication process is support of the thin (< 10 um) detector during the MBE growth by oxide-bonding to a full-thickness silicon wafer. This back-illumination process makes it possible to build low-dark-count-rate single-photon detectors with high quantum efficiency extending to deep ultraviolet wavelengths. This paper reviews our process for fabricating MBE back-illuminated silicon Geigermode avalanche photodiode arrays and presents characterization of initial test devices.
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Summary

We have demonstrated a wafer-scale back-illumination process for silicon Geiger-mode avalanche photodiode arrays using Molecular Beam Epitaxy (MBE) for backside passivation. Critical to this fabrication process is support of the thin ( 10 um) detector during the MBE growth by oxide-bonding to a full-thickness silicon wafer. This back-illumination process makes...

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Microwave photonic applications of slab-coupled optical waveguide devices

Published in:
2010 23rd Annual Mtg. of the IEEE Photonics Society, 10 November 2010, pp. 479-480.
Topic:

Summary

The semiconductor slab-coupled optical waveguide (SCOW) concept is a versatile device platform that has enabled new classes of high-power, low-noise single-frequency lasers, mode-locked lasers, optical amplifiers, and photodiodes for analog optical links and photonic analog-to-digital converters.
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Summary

The semiconductor slab-coupled optical waveguide (SCOW) concept is a versatile device platform that has enabled new classes of high-power, low-noise single-frequency lasers, mode-locked lasers, optical amplifiers, and photodiodes for analog optical links and photonic analog-to-digital converters.

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