This paper presents experimental results obtained with Ziva Corp.'s image processing approach called Computational Imaging for Aberrated Optics (CIAO), which is a multi-image deconvolution algorithm. CIAO enhances the performance of imaging systems by accommodating wavefront error. This accommodation allows the designer to improve system performance or reduce system cost. CIAO has been successfully tested in a wide field of view imaging system, which has significant aberrations. These experimental results show CIAO restoration of high quality images from highly blurred images. Specifically, CIAO allows the pupil to open >50% beyond the diffraction limited aperture, which allows more light capture and higher cut-off resolution.

We propose to use low-coherence-length cw optical sources with a broad spectrum in heterodyne near-field scanning microscopy in order to imitate optical pulse propagation and to obtain information about spectrally variant properties of nanophotonic components. The dispersion difference in the interferometer arms for a symmetric acousto-optic modulator arrangement is shown to be negligible over appreciable bandwidths. Demonstration of the principle of operation and viability of this approach is provided by measurement of the group refractive index of a silicon channel waveguide.

A strongly coupled, chirped Bragg grating made by sinusoidally modulating the sidewalls of a silicon waveguide is designed, fabricated, and experimentally characterized. By varying the device parameters, the operating wavelength, device bandwidth, sign (normal or anomalous), and magnitude of group-velocity dispersion may be engineered for specific photonic applications. Asymmetric Blackman apodization is best suited for maximizing the useable bandwidth while providing good ripple suppression. Dispersion values up to 7.0 x 10(5) ps/nm/km are demonstrated at 1.55 microm.

Fourier methods are widely used in optical information processing for time domain waveform synthesis and detection. In such approaches an input pulse is spectrally decomposed and modulated by an appropriately designed spectral filter. In general, various ultrafast applications may need either generation or characterization of waveforms depending whether their frequency response is or is not known a priori. Ultrafast pulses prove useful in driving or probing such systems because their broad, deterministic complex spectral amplitude "sees" a large continuous portion of the system transfer function. Traditionally, space domain spectral decomposition is used to perform optical Fourier processing, where pairs of gratings and lenses are used to decompose the spectral content of the pulsed, optical waveforms. Liquid crystal and acousto-optic (AO) modulators provide a means for introduction of somewhat arbitrary system transfer functions. More recently, compact waveguide-based approaches have used arrayed waveguide gratings (AWGs) to perform an analogous spectral decomposition to those achieved with traditional, free-space coupled gratings. Information processing arrangements using the space domain for transverse spectral decomposition benefit from the maturity of such techniques, with respect to basic understanding, component quality, and the excellent phase control that free-space manipulations provide. Component insensitivity to optical power permits the shaping and detecting of high peak power pulses used to drive nonlinear optical systems. Furthermore, nonlinear optical elements can be introduced directly into these processors to provide unique ultrafast waveform synthesis capabilities with response times in the range of femtoseconds. Drawbacks to free-space approaches include scaling in volume to achieve large time bandwidth products (TBWPs) and limiting the temporal extent of waveforms coupled back into a single-mode fiber (SMF). The origin of this last restraint is the time∕space interrelation inherent in traditional pulse shaping devices. AWG approaches rely on complex waveguide elements to circumvent large processor volumes and time∕space coupling issues, but they too are practically limited by fabrication requirements. The number of resolvable spots in the output waveform for both Fourier synthesis and direct space-to-time AWG approaches is equal to the number of waveguide channels. An alternative approach to Fourier processing relying on a single transverse spatial mode can better integrate with fiber systems and photonic lightwave circuits and will scale in length only for the achievement of large TBWPs. Fiber-based and fiber-integrated processors can manipulate optical waveforms in the time domain exploiting chromatic dispersion for longitudinal spectral decomposition and applying to it Fourier synthesis techniques. Drawing on the identical mathematical treatments of diffraction in space and dispersion in time, an approximate Fourier transform (FT) of an incident optical signal is achieved via chromatic dispersion after reaching the so-called "far-field approximation." With such an amount of dispersion, the temporal waveform closely resembles the spectrum. Such a waveform is called a longitudinal spectral decomposition wave (SDW). A time-variant element (e.g., modulator) filters this SDW. And it is possible to recompose the pulse waveform through propagation in a conjugate dispersion source matched (i.e., of opposite sign but equal magnitude) to the first dispersive element. The number of resolvable spots that such a processor offers relies on a suitable modulation scheme and the experimental ability to disperse a sub-picosecond pulse using second-order dispersion.

A continuously tunable optical delay line providing over 105 ns of 10-Gb/s optical channel is reported using a two-pump parametric process in a nonlinear optical fiber. Performance limits are measured and compared with recently reported all-optical delay results. The figure of merit defined by the delay-bandwidth product is 1055.

We introduce and present experimental evaluations of loss and nonlinear optical response in a waveguide and an optical resonator, both implemented with a silicon nitride/ silicon dioxide material platform prepared by plasma-enhanced chemical vapor deposition with dual frequency reactors that significantly reduce the stress and the consequent loss of the devices. We measure a relatively small loss of approximately 4dB/cm in the waveguides. The fabricated ring resonators in add-drop and all-pass arrangements demonstrate quality factors of Q=12,900 and 35,600. The resonators are used to measure both the thermal and ultrafast Kerr nonlinearities. The measured thermal nonlinearity is larger than expected, which is attributed to slower heat dissipation in the plasma-deposited silicon dioxide film. The n2 for silicon nitride that is unknown in the literature is measured, for the first time, as 2.4 x 10(-15)cm(2)/W, which is 10 times larger than that for silicon dioxide.

We describe what we believe to be novel methods for waveform synthesis and detection relying on longitudinal spectral decomposition of subpicosecond optical pulses. Optical processing is performed in both all-fiber and mixed fiber-free-space systems. Demonstrated applications include ultrafast optical waveform synthesis, microwave spectrum analysis, and high-speed electrical arbitrary waveform generation. The techniques have the potential for time-bandwidth products of > or =10(4) due to exclusive reliance on time-domain processing. We introduce the principles of operation and subsequently support these with results from our experimental systems. Both theory and experiments suggest third-order dispersion as the principle limitation to large time-bandwidth products. Chirped-fiber Bragg gratings offer a route to increasing the number of resolvable spots for use in high-speed signal processing applications.

Silicon nitride /silicon dioxide waveguide using plasma-enhanced chemical vapor deposition is reported, which has the loss of ~4 dB/cm. A ring resonator using the waveguide gives the Q of 12,900 and its nonlinear response is studied.

A strongly coupled, chirped Bragg grating with sinusoidally modulated sidewalls is proposed for on-chip dispersion compensation. The device bandwidth, magnitude and sign of dispersion may be engineered for specific dispersion compensation requirements.

A phase-modulated optical signal was translated over record 1065nm, from the near-infrared band to the visible band. A Gbps phase-modulated signal was received in an error-free manner in the visible band for the first time.

The inclusion of a linear chirped fiber Bragg grating for short pulse dispersion is shown to enhance the time domain realization of optical frequency-domain reflectometry. A low resolution demonstrator is constructed with single surface scans containing 140 resolvable spots. The system dynamic range meets that shown in earlier demonstrations without digital post-processing for signal linearization. Using a conjugate pair of chirped pulses created by the fiber grating, ranging is performed with position and velocity information decoupled. Additionally, by probing the target with short pulses and introducing grating dispersion just before photodetection, velocity immune ranging is demonstrated.

Wavelength conversion based on degenerate four-wave mixing in a photonic crystal fiber with two zero-dispersion wavelengths is investigated both theoretically and experimentally. The proposed concept of universal band translation in a single-pass traveling-wave structure offers a wavelength band rather than a single-wavelength mapping between distant spectral ranges. Near-infrared signals are modulated using both harmonic and pseudorandom bit sequences and translated to the visible optical band. Multiple-channel translation, which produces wavelength-division-multiplexed idlers in the visible band, is demonstrated for the first time. The performance of the translation process is measured both spectrally and temporally for both single- and multiple-channel signals

An approach for time bandwidth product maximization in chirped pulse optical ranging systems is treated theoretically and accompanied by experimental demonstrations. Signal processing offers a route to a straight-forward, low-cost implementation.

We demonstrate an extended dispersion-limited reach of 600 km at 10 Gb/s with a conventional NRZ transmitter in the absence of optical dispersion compensation. The novel approach combines a new type of spectral channel narrowing and electronic processing based on a reduced complexity Viterbi algorithm at the receiver.

We describe a novel method for subpicosecond pulse shaping based on longitudinal spectral decomposition in dispersive media. The entire system is created with standard telecommunications equipment allowing for integration with optical communication networks. The technique has the potential for time–bandwidth products ⩾104 due to exclusive reliance on time-domain processing. We introduce the principle of operation and subsequently support it with results from our experimental system. Both theory and experiments suggest third-order dispersion as the principle limitation to realizing a large number of resolvable spots. Chirped fiber Bragg gratings offer a route to increase the time–bandwidth product for high-speed signal processing applications.

Ultra wideband (UWB) microwave signals are receiving much attention for their potential use in both radar systems and high-speed data links. The currently available arbitrary waveform generation (AWG) devices operates up to only a few gigahertz. The desire to create UWB signals with carrier frequencies in the 10s of GHz and fractional bandwidths approaching 100% suggests investigating microwave-photonic approaches. In this paper, the authors demonstrate a method for electrical AWG with independent envelope and carrier control though the manipulation of wide bandwidth optical pulses in a time-domain processor.

Exact signal statistics for fiber-optic links containing a single optical pre-amplifier are calculated and applied to sequence estimation for electronic dispersion compensation. The performance is evaluated and compared with results based on the approximate chi-square statistics. We show that detection in existing systems based on exact statistics can be improved relative to using a chi-square distribution for realistic filter shapes. In contrast, for high-spectral efficiency systems the difference between the two approaches diminishes, and performance tends to be less dependent on the exact shape of the filter used.

A natural criterion of performance optimization in a communication system is that of minimizing the probability of error. In this paper, the authors derive the signal statistics by means of Karhunen-Loeve expansions such that the signal waveforms and the noise before the square-law detector are projected onto a set of orthonormal basis.