David Sinefeld

Sub-banded / single-sub-carrier drop-demux and flexible spectral shaping with a fine resolution photonic processor

Spectral processor based on arrayed waveguide grating and free-space manipulation is capable of arbitrary filtering at record metrics of 0.8GHz resolution over 200GHz span. Narrowband coherent drop-demultiplexing and controlled optical shaping is demonstrated in unison with digital sub-banding.

A photonic spectral processor employing two-dimensional WDM channel separation and a phase LCoS modulator

We propose and demonstrate a spectral phase and amplitude modulator spanning full 2D-space by crossing a 100 GHz WGR and a 1200 gr/mm bulk grating. We address individual WDM channels with high resolution (4.5 GHz) and addressability (0.2 GHz).

Hybrid Guided-Wave/Free-Space Optics Photonic Spectral Processor Based on LCoS Phase Only Modulator

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.

Adaptive optics in multiphoton microscopy: comparison of two, three and four photon fluorescence

We demonstrate adaptive optics system based on nonlinear feedback from 3- and 4-photon fluorescence. The system is based on femtosecond pulses created by soliton self-frequency shift of a 1550-nm fiber-based femtosecond laser together with micro-electro-mechanical system (MEMS) phase spatial light modulator (SLM). We perturb the 1020-segment SLM using an orthogonal Walsh sequence basis set with a modified version of three-point phase shifting interferometry. We show the improvement after aberrations correction in 3-photon signal from fluorescent beads. In addition, we compare the improvement obtained in the same adaptive optical system for 2-, 3- and 4-photon fluorescence using dye pool. We show that signal improvement resulting from aberration correction grows exponentially as a function of the order of nonlinearity.

Wavelength-selective switch with direct few mode fiber integration

The first realization of a wavelength-selective switch (WSS) with direct integration of few mode fibers (FMF) is fully described. The free-space optics FMF-WSS dynamically steers spectral information-bearing beams containing three spatial modes from an input port to one of nine output ports using a phase spatial light modulator. Sources of mode dependent losses (MDL) are identified, analytically analyzed and experimentally confirmed on account of different modal sensitivities to fiber coupling in imperfect imaging and at spectral channel edges due to mode clipping. These performance impacting effects can be reduced by adhering to provided design guidelines, which scale in support of higher spatial mode counts. The effect on data transmission of cascaded passband filtering and MDL build-up is experimentally investigated in detail.

Insertion Loss and Crosstalk Analysis of a Fiber Switch Based on a Pixelized Phase Modulator

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.

All-channel tunable optical dispersion compensator based on linear translation of a waveguide grating router.

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 50 km fiber with a -2 dB power penalty at 10⁻⁹.

Nyquist-WDM filter shaping with a high-resolution colorless photonic spectral processor.

We employ a spatial-light-modulator-based colorless photonic spectral processor with a spectral addressability of 100 MHz along 100 GHz bandwidth, for multichannel, high-resolution reshaping of Gaussian channel response to square-like shape, compatible with Nyquist WDM requirements.

Tunable fiber ring laser with an intracavity high resolution filter employing two-dimensional dispersion and LCoS modulator

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.

Photonic spectral processor employing two-dimensional WDM channel separation and a phase LCoS modulator

We propose and demonstrate a spectral phase and amplitude modulator spanning full 2D-space by crossing a 100GHz WGR and a 1200gr/mm bulk grating. We address individual WDM channels with high resolution (4.5GHz) and addressability (0.2GHz).