Non-reversing relaxation enthalpies (ΔH(nr)) at glass transitions T(g)(x) in the P(x)Ge(x)Se(1-2x) ternary display wide, sharp and deep global minima ([Formula: see text]) in the 0.09

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We design and fabricate a 320 nm slot for an electro-optic (E-O) polymer infiltrated silicon photonic crystal waveguide. Because of the large slot width, the poling efficiency of the infiltrated E-O polymer (AJCKL1/amorphous polycarbonate) is significantly improved. When coupled with the slow light effect from the silicon photonic crystal waveguide, an effective in-device r(33) of 735 pm/V, which to our knowledge is a record high, is demonstrated, which is ten times higher than the E-O coefficient achieved in thin film material. Because of this ultrahigh E-O efficiency, the V(π)L of the device is only 0.44 V mm, which is to our knowledge the best result of all E-O polymer modulators.

We demonstrate a 300 μm long silicon photonic crystal (PC) slot waveguide device for on-chip near-infrared absorption spectroscopy, based on the Beer-Lambert law for the detection of methane gas. The device combines slow light in a PC waveguide with high electric field intensity in a low-index 90 nm wide slot, which effectively increases the optical absorption path length. A methane concentration of 100 ppm (parts per million) in nitrogen was measured.

We experimentally demonstrated photonic crystal microcavity based resonant sensors coupled to photonic crystal waveguides in silicon nano-membrane on insulator for chemical and bio-sensing. Linear L-type microcavities are considered. In contrast to cavities with small mode volumes, but low quality factors for bio-sensing, we showed increasing the length of the microcavity enhances the quality factor of the resonance by an order of magnitude and increases the resonance wavelength shift while retaining compact device characteristics. Q~26760 and sensitivity down to 15 ng/ml and~110 pg/mm2 in bio-sensing was experimentally demonstrated on silicon-on-insulator devices.

We design and demonstrate a compact and low-power band-engineered electro-optic (EO) polymer refilled silicon slot photonic crystal waveguide (PCW) modulator. The EO polymer is engineered for large EO activity and near-infrared transparency. A PCW step coupler is used for optimum coupling to the slow-light mode of the band-engineered PCW. The half-wave switching-voltage is measured to be Vπ=0.97±0.02V over optical spectrum range of 8nm, corresponding to the effective in-device r33 of 1190pm/V and Vπ×L of 0.291±0.006V×mm in a push-pull configuration. Excluding the slow-light effect, we estimate the EO polymer is poled with an efficiency of 89pm/V in the slot. [6]. The fabrication process of these devices involves the poling of the EO polymer at an elevated temperature. Unfortunately, the leakage current due to the charge injection through silicon/polymer interface significantly reduces the poling efficiency in narrow slot waveguides (slot width, S w <200nm). Among the abovementioned structure, the slot PCW can support optical mode for S w as large as 320nm [7]. Such a wide slot was shown to reduce the leakage current by two orders of magnitude resulting in 5х improvement in the in-device r 33 compared to a slot PCW with S w =75nm [7].One problem remains among slot PCW modulators is their narrow operating optical bandwidth of <1nm [8][9][10] because of the high group velocity dispersion (GVD) in the slow-light optical spectrum range. To broaden the operating optical bandwidth of PCW modulators, lattice shifted PCWs can be employed, where the spatial shift of certain holes can modify the structure to provide low-dispersion slow light [11][12][13][14][15].In this letter we report a symmetric MZI modulator based on band-engineered slot PCW refilled with EO polymer, SEO125 from Soluxra, LLC. SEO125 exhibits exceptional combination of large EO activity, low optical loss, and good temporal stability. Its r 33 value of poled thin films is around 125pm/V at the wavelength of 1310 nm, which is measured by the Teng-Man reflection technique. The design and synthesis of SEO125 encompasses recent development of highly efficient nonlinear optical chromophores with a few key molecular and material parameters, including large β values, good near-infrared transparency, excellent chemicaland photo-stability, and improved processability in polymers [16]. Using a band-engineered EO polymer refilled slot PCW with S w =320nm, we demonstrate a slow-light enhanced effective in-device r 33 of 1190pm/V over 8nm optical spectrum range. Excluding the slow-light effect, we estimate in-device material' r 33 of 89pm/V for SEO125 in the slot that show 51% improvement compared to the results (59pm/V) in [7]. A schematic of the device on silicon on insulator (SOI) (Si thickness=250nm, oxide thickness=3μm) is shown in Fig. 1 (a). The input and output strip waveguides are connected to the device using a strip-to-slot waveguide mode converter. PCW couplers consisting of a fast-light section [17] connect the mode converters to a 300μm-long slow-ligh...

Melt dynamics and glass Topological phases of especially dry and homogenized binary As x S 100−x melts/glasses are examined in Modulated-DSC, Raman scattering, and volumetric experiments. In the S-rich glasses (12% < x < 23%), direct evidence for the elusive 537 cm −1 stretch vibrational mode of the Quasi-Tetrahedral (QT), S = As(S 1/2 ) 3 , local structure is observed in FT-Raman scattering once melts are homogenized and glasses cycled through T g +10 • C for an extended period. The enthalpy of relaxation at T g , H nr (x), fragility index, m(x), Molar volumes, V m (x) each display three distinct regimes of variation. Specifically, m(x) displays a Gaussian like global minimum (fragility window), and H nr (x) displays an abrupt square-well like variation (reversibility window), while V m (x) displays a Gaussian-like local minimum (Volumetric window) in the isostatically rigid phase (22.5% < x < 28.5%). At low x (<20%) in the Flexible phase, glasses are segregated with a S 8 -rich nanophase that decouples from the As-S glassy backbone. At medium x (22.5% < x < 28.5%) glassy backbones form an isostatically rigid phase displaying a vanishing H nr (x) term, and compacted structures with corresponding melts being superstrong (m < 20). At high x (28.5% < x < 40%) in the Stressed-Rigid phase, glasses possess an increasing H nr (x) term, and melts become increasingly fragile, with m(x)>20 as x increases. Taken together, these results underscore that superstrong melts yield isostatically rigid glasses, while fragile ones form either Flexible or Stressed-rigid glasses upon cooling. The onset of the rigidity transition near = 2.22, instead of the usual value of = 2.40, is identified with presence of QT local structures in addition to Pyramidal As(S 1/2 ) 3 local structures in the glassy backbone, and with a small but finite fraction of polymeric S n chains being decoupled from the backbone.

A silicon/organic hybrid modulator integrating photonic crystal ͑PC͒ waveguide, 75 nm slot, and electro-optic ͑EO͒ polymer is experimentally demonstrated. Slow light in PC waveguide and strong field confinement in slot waveguide enable ultraefficient EO modulation with a record-low V ϫ L of 0.56 V mm and an in-device effective r 33 of 132 pm/V. This result makes it the most efficient EO polymer modulator demonstrated to date. The modulated signal shows strong wavelength dependence and peak enhancement of 23 dB near the band edge of defect mode, which confirms the signature of the slow light effect.