We demonstrate high resolution and increased efficiency background-free time-to-space conversion using spectrally resolved non-degenerate and collinear SFG in a bulk PPLN crystal. A serial-to-parallel resolution factor of 95 and a time window of 42 ps were achieved. A 60 fold increase in conversion efficiency slope compared with our previous work using a BBO crystal [D. Shayovitz and D. M. Marom, Opt. Lett. 36, 1957 (2011)] was recorded. Finally the measured 40 GHz narrow linewidth of the output SFG signal implies the possibility to extract phase information by employing coherent detection techniques. ©2012 Optical Society of America

We demonstrate passive generation of optical pulse trains with each pulse having distinct center carrier and spectra using tunable group delay (GD) staircase transfer functions. The GD steps result from opposite and equal magnitude GD slopes from narrowband and wideband tunable optical dispersion compensators. We use this technique to split the spectrum of a femtosecond pulse to a pulse burst with precise control of pulse time separation. © 2012 Optical Society of America

An optimization procedure for spatial mode multiplexing from individual single-mode fibers into a three-mode fiber based on a spatial aperture sampling concept has been developed. By placing space-variant imaging elements between the single-mode and few-mode fibers, each beam aperture can be shaped for lower loss coupling and low mode-dependent losses. The optimization achieves a record theoretical −1.5-dB insertion loss, improving on the previous theoretical −2-dB record.

We present a Photonic Spectral Processor (PSP) that provides both fine spectral resolution and broad bandwidth support by dispersing light over two-dimensional space using the crossed-grating approach. The PSP uses a hybrid guided wave/free-space optics arrangement, where a waveguide grating router implemented in silica waveguides disperses the light in one dimension with a 100 GHz FSR and a bulk 1200 gr/mm diffraction grating disperses the light along the second (crossed) dimension. The diffracted light is focused by a lens onto a liquid-crystal on silicon, two-dimensional, phase-only, spatial light modulator, which we use to prescribe phase and amplitude to the signal’s spectral components. With the 2-D PSP arrangement we are able to address frequency components at 0.2 GHz/column with an optical resolution of 3.3 GHz covering 40 C-band channels. ©2011 Optical Society of America

We investigate and analyze temporal soliton interactions with a dispersive truncated Airy pulse traveling in a nonlinear fiber at the same center wavelength (or frequency), via split step Fourier numerical simulation. Truncated Airy pulses, which remain self-similar during propagation and have a ballistic trajectory in the retarded time frame, can interact with a nearby soliton by its accelerating wavefront property. We find by tracking the fundamental parameters of the emergent soliton-time position, amplitude, phase and frequency—that they alter due to the primary collision with the Airy main lobe and the continuous copropagation with the dispersed Airy background. These interactions are found to resemble coherent interactions when the initial time separation is small and incoherent at others. This is due to spectral content repositioning within the Airy pulse, changing the nature of interaction from coherent to incoherent. Following the collision, the soliton intensity oscillates as it relaxes. The initial parameters of the Airy pulse such as initial phase, amplitude and time position are varied to better understand the nature of the interactions. ©2011 Optical Society of America OCIS codes: (190.0190) Nonlinear

We report the first demonstration, to our knowledge, of time-to-space conversion of 1.55 μm femtosecond optical pulses using nondegenerate, collinearly phase-matched sum-frequency generation. A quasi-monochromatic and background-free output signal spanning a time window of 35 ps and with a pulse image width of 350 fs was achieved. The resulting serial-to-parallel resolution factor of 100 demonstrates the potential for all-optical complete frame demultiplexing of a 1 Tbit-s optical time-division multiplexing bit stream. © 2011 Optical Society of America

We simulate and analyze the propagation of truncated temporal Airy pulses in a single mode fiber in the presence of self-phase modulation and anomalous dispersion as a function of the launched Airy power and truncation coefficient. Soliton pulse shedding is observed, where the emergent soliton parameters depend on the launched Airy pulse characteristics. The Soliton temporal position shifts to earlier times with higher launched powers due to an earlier shedding event and with greater energy in the Airy tail due to collisions with the accelerating lobes. In spite of the Airy energy loss to the shed Soliton, the Airy pulse continues to exhibit the unique property of acceleration in time and the main lobe recovers from the energy loss (healing property of Airy waveforms). ©2011 Optical Society of America

We demonstrate a tunable fiber ring laser employing a two-dimensional dispersion arrangement filter, with the lasing determined by a liquid crystal on silicon (LCoS) spatial light modulator. Lasing wavelengths can be tuned discontinuously across the communication C-band at an addressable resolution of less than 200 MHz. We introduce full characterization of the laser output including phase and amplitude stability and short and long-term bandwidth measurements. © 2011 Optical Society of America

We propose and demonstrate a compact tunable optical dispersion compensation (TODC) device with a 100 GHz free spectral range capable of mitigating chromatic dispersion impairments. The TODC is based on longitudinal movement of a waveguide grating router, resulting in chromatic dispersion compensation of 1000 ps/nm. We employed our TODC device for compensating 42.8 Gbit/sec differential phase-shifting keying signal, transmitted over 50km fiber with a −2 dB power penalty at 10⁻⁹.

We analyze the performance of a spatial fiber switching system when using a pixelized mirror, such as a LCoS or MEMS spatial light modulator, in place of a large tilting micromirror. Our findings demonstrate the dependence of insertion losses on tilt angles or fiber counts, and the dependence of the crosstalk in the number of phase quantization levels and random phase errors. The former effects can be minimized by satisfying a relationship between the tilt angle to a fiber, the pitch of the array, and the optical wavelength.

We propose and demonstrate a photonic spectral processor for applying arbitrary spectral phase and amplitude at high resolution with a 100-GHz free-spectral range for colorless wavelength-division-multiplexing adaptive filtering applications. The system employs free-space optics for projecting the dispersed light coming out of a planar-lightwave circuit onto a phase spatial-light modulator. The processor achieves 3-GHz optical resolution over 75-GHz usable bandwidth, with 557-MHz addressable granularity.

Optical communication systems are the premier conduit for providing broadband data across continents, nations, cities, neighborhoods, and are now starting to penetrate into private homes. This spectacular achievement is the culmination of years of research and development efforts in diverse fields. Recently we are witnessing the evolution of these communication systems towards optical networking. The advent of optical networking has been enabled by a suite of complementary optical subsystems that are pivotal to the operation and management of these networks. These optical microsystems directly interact with the optical signal and-through functionality afforded by design-are able to filter, switch, attenuate, and adapt the optical communication channels carried by the network. In this talk I will review a sampling of these enabling devices and focus on the MEMS technology required for its implementation.

A novel tunable dispersion compensator (TDC) with ±500-ps/nm tuning range and bandwidth support for 40-Gb/s signals is described. The TDC is constructed from a waveguide grating router (WGR) that provides very high spatial dispersion and a deformable cylindrical mirror for applying quadratic spatial phase across the dispersed wavefront. The WGR’s 100-GHz free-spectral range (FSR) allows the device to simultaneously apply the same dispersion to all wavelength-division multiplexing (WDM) channels.

Optical transport capacities have grown significantly in the last decade to meet the increased demands on communications networks. This growth has been achieved both by increases in individual channel rates, which are based on time division multiplexing (TDM), and by increased channel counts, through the use of dense wavelength division multiplexing (DWDM). Yet increasing optical transport capacity alone is insufficient to scale the network; the underlying data needs to be delivered from numerous geographically diverse originating locations to similarly diverse terminating locations, requiring increasing switching capacity to facilitate this networking need. Since the growth in the individual TDM channel rates is driven by the capabilities of electronics, it is reasonable to expect that the switching capacity of electronics will tend to track this trend, although because of the challenges in high data rate interconnects it is unlikely to exceed it. This leaves the challenge of managing the increased bandwidth attained through the use of DWDM. Management of this bandwidth in the optical layer is an attractive proposition if eliminating unnecessary high-speed electronics in the path of an optical signal can reduce the complexity of the network and the associated equipment costs. These optical bandwidth management elements are classified according to the degree of switching, as either reconfigurable optical add/drop multiplexers (ROADM) or wavelength selective cross-connects (WSXC), analogous to the add/drop multiplexers and digital cross-connects of the TDM domain. We generalize these elements and describe whether the switching provides functions that are multicolored, colorless, or colored, and whether the channels are fixed data rate or rateless. We review the wavelength selective switch (WSS) components that perform the necessary switching function and present two successful technology platforms that can be used to construct them: planar lightwave circuits (PLC) and micro-electromechanical systems (MEMS). We also discuss future directions for WSS technologies and device functionality to more flexibly manage bandwidth in the optical layer. © 2006 Lucent Technologies Inc.

The design and performance of several generations of wavelength-selective 1 X K switches are reviewed. These optical subsystems combine the functionality of a demultiplexer, per-wavelength switch, and multiplexer in a single, low-loss unit. Free-space optics is utilized for spatially separating the constituent wavelength division multiplexing (WDM) channels as well as for space-division switching from an input optical fiber to one of K output fibers (1 X K functionality) on a channel-by-channel basis using a microelectromechanical system (MEMS) micromirror array. The switches are designed to provide wide and flat pass- bands for minimal signal distortion. They can also provide spectral equalization and channel blocking functionality, making them well suited for use in transparent WDM optical mesh networks.

This paper describes a continuously variable and independently addressable channelized dispersion compensator. The optical system is a free-space grating-based system used in a four-pass configuration to ensure flat passbands. The variable dispersion is produced by an array of thermally adaptable curvature micromechanical mirrors. A per-channel variable dispersion greater than +/-400 ps/nm has been demonstrated, with 58 GHz +/-0.4 dB flat passband on 85 GHz spacing. The group delay ripple is less than 7 ps and the penalty with 40 Gb/s CSRZ is 0.7 dB.

We introduce a general concept for the design of all-optical wavelength converters with pulse reformatting functionality. The novel wavelength converters are based on a single semiconductor optical amplifier followed by an optical filter. A microelectromechanical system-based realization is shown and simultaneous 40 Gb/s wavelength conversion, switching and signal format conversion is demonstrated. The new pulse reformatting optical filter device outperforms current schemes with respect to input-power requirements, input-power dynamic range and signal quality.

Free-space-based channelized dynamic spectral equalizers are theoretically investigated by solving the temporal-frequency-dependent power-coupling integral for commonly used active device technologies: liquid-crystal modulators, tilting micromirror arrays, and deformable gratings. Channel-filter characteristics, such as bandwidth and interchannel transition, are found to depend on the different attenuation mechanisms provided by the active devices. Such information is required for choosing the proper device parameters in designing channel equalizers and similar free-space spatially dispersed subsystems.

In part I, we proposed and investigated a hybrid pulse position modulation/ultrashort light pulse code-division multiple-access (PPM/ULP-CDMA) system for ultrafast optical communication networks. In this scheme, the large bandwidth of a ULP is efficiently utilized by virtue of the very high time resolution of a time-space processor. More detailed analysis and discussion on the receiver scheme using the time-space processor is now presented; nonideal performance of the time-space processor, including the reference pulse realization problem, as well as amplifier and detector noise, are taken into account. Discussions on physically achievable ranges of the system parameters that determine the performance of the proposed PPM/ULP-CDMA system are also made based upon current, state of the art technology. As remedies to overcome the physical limitations on the system parameters, two modified modulation/demodulation schemes are proposed and investigated to enhance the performance of the hybrid PPM/ULP-CDMA system.

A new approach is presented for fabricating monolithic crystalline silicon tilting-mirror microoptoelectromechanical systems (MOEMS) devices. The activation electrodes, etched from a thick silicon layer deposited over insulating oxide onto the top surface of a silicon-on-insulator (SOI) wafer, are displaced from the mirrors and interact with these tilting elements via electrostatic fringing fields. In contrast to the more usual parallel-plate activation, the rotation angle saturates at high voltages. This paper discusses concept, design, and processing, and also compares modeling and measured performance of a specific 9 tilt range device array.