Record Low Loss Research Articles

High Δn strip-loaded electro-optic polymer waveguide modulator with low insertion loss

We demonstrate a novel electro-optic polymer modulator design which shows a record low optical insertion loss of 5.7 dB at 1550 nm. The modulator consists of a high numerical aperture passive waveguide which is converted to a strip-loaded electro-optic polymer waveguide through refractive index tapers. The device is fabricated using all wet-etch techniques which results in low excess loss from roughness created during fabrication and, employs new low loss passive sol-gel materials. The fabricated device also shows a low half-wave voltage of 2.8 V.

Disorder-induced scattering loss of line-defect waveguides in photonic crystal slabs

Detailed propagation loss spectrum measurements for line-defect waveguides in silicon photonic crystal slabs are presented, which show record low loss values $(5\phantom{\rule{0.3em}{0ex}}\mathrm{dB}∕\mathrm{cm})$ and complicated frequency dependence. We quantitatively analyze the origin of the loss spectrum shape using a photon Green function theory and obtain a very good agreement, thus providing an explanation of the complex physical mechanisms responsible for the observed propagation loss. In particular, we demonstrate the influence of out-plane, backward, intermode, and in-plane scattering processes on the observed loss spectra, induced by the structural disorder that occurs during fabrication, and highlight the importance of backward and intermode scattering in these waveguides.

Advances in Efficiency, Speed Reported at OFC 2004

Researchers unveiled impressive results in component design and system performance at OFC 2004. Highlights included record low loss in a hollow photonic bandgap fiber and all-optical packet switching at a staggering rate of 160 Gbit/s.

Ultra-low loss photonic integrated circuit with membrane-type photonic crystal waveguides

We report the design and testing of an SOI-based photonic integrated circuit containing two-dimensional membrane-type photonic crystal waveguides. The circuit comprises spot-size converters to efficiently couple light from a fiber into single-mode strip waveguides and butt-couplers to couple from strip waveguides to photonic crystal waveguides. Each optical interface was optimized to minimize back-reflections and reduce the Fabry-Perot noise. The transmission characteristics of each component are measured and record low propagation losses in photonic crystal waveguides of 24dB/cm are reported. The combination of an efficient two-stage coupling scheme and utilization of ultra-long (up to 2mm) photonic crystal waveguides reduces the uncertainty in determining the loss figure to 3dB/cm.

Guided-wave electrooptic devices utilizing static strain induced effects in ferroelectrics

The static strain optic (SSO) effect has been used in different ferroelectric substrate materials as a means of producing channel waveguides and various integrated optic devices. The static strain results from the large thermal expansion mismatch between the substrate and a thick film of SiO2 that is deposited on the surface at an elevated temperature and patterned at room temperature. Record low loss channel waveguides have been produced in tungsten bronze substrates SBN and BSTN, which have electrotrooptic coefficients ∼ an order of magnitude greater than LiNbO3. GHz-bandwidth electrooptic modulation in the tungsten bronzes was obtained without repoling the crystal after processing at temperatures far above. Tc . In another application of the SSO effect, phase-matched polarization coupling has been used in an electrooptically tunable TE-TM mode converter and a channel dropping filter in LiTaO3.

InGaAsP/InP tapered active layer multiquantum welllaser with1.8 dB coupling loss to cleaved singlemode fibre

Tapered active layer MQW BH lasers with spot sizes closely matched to cleaved fibre are reported. A record low coupling loss of 1.8 dB to 101 mu m core cleaved singlemode fibre has been obtained for a device with an 800 mu m long taper. >

Instrumental effects in the electron loss spectra from surfaces due to the use of LEED optics

The use of a conventional retarding grid LEED-Auger apparatus to record low energy loss spectra from single crystal surfaces has been shown to produce spurious structure in the region within approximately 10 eV from the elastic peak. With the aid of miniature electron guns mounted on the crystal manipulator this structure was shown to arise from transmission effects at the retarding grids when a collimated monoenergetic beam of electrons traverses a limited number of retarding grid meshes. This effect was attributed to an uneven distortion of the electron trajectories due to the use of woven mesh in the manufacture of the grids. It was concluded that low energy loss spectra from single crystal surfaces which are free of this kind of instrumental artifact may be ensured with the incident electrons at normal incidence and at an energy which is sufficiently low so that all LEED beams are excluded from the analysis. Under these conditions the loss spectrum from a W(100) surface contained two broad losses at 2.7 and 5.2 eV which were attributed to interband transitions.