Real-time hybrid angular-interrogation surface plasmon resonance sensor in the near-infrared region for wide dynamic range refractive index sensing.

Herein, we integrated angle-scanning surface plasmon resonance (SPR) and angle-fixed SPR as a hybrid angular-interrogation SPR to enhance the sensing performance. Galvanometer-mirror-based beam angle scanning achieves a 100-Hz acquisition rate of both the angular SPR reflectance spectrum and the angle-fixed SPR reflectance, whereas the use of near-infrared light enhances the refractive index (RI) sensitivity, range, and precision compared with visible light. Simultaneous measurement of the angular SPR reflectance spectrum and angle-fixed SPR reflectance boosts the RI change range, RI resolution, and RI accuracy to 10-1-10-6 RIU, 2.24 × 10-6 RIU, and 5.22 × 10-6 RIU, respectively. The proposed hybrid SPR is a powerful tool for wide-dynamic-range RI sensing with various applications.

Thermal control of a Kerr microresonator soliton comb via an optical sideband.

We report the thermal control of a dissipative Kerr microresonator soliton comb via an optical sideband generated from an electro-optic modulator. Same as the previous reports using an independent auxiliary laser, our sideband-based (S-B) auxiliary light also enables access to a stable soliton comb and reduces the phase noise of the soliton comb, greatly simplifying the set-up with an auxiliary laser. More importantly, because of the intrinsically high frequency/phase correlation between the pump and S-B auxiliary light, the detuning between the pump and resonance frequency is automatically almost fixed, which allows an 18 times larger "effective" soliton existence range than the conventional method using an independent auxiliary laser, as well as a scanning of the soliton comb of more than 10 GHz without using microheaters.

Investigation of the phase noise of a microresonator soliton comb.

Optical frequency combs generated from microresonators (especially microresonator soliton combs) have been attracting significant attentions because of the potential to be fully chip-scale. Among various promising applications of soliton combs, coherent optical communications and mm/THz wireless communications require low phase noise of the comb modes and low relative phase noise between the comb modes, respectively. Here, we measure the phase noise of a soliton comb, investigating how the thermorefractive noise of a microresonator influences on the phase noise. We observe the quadratic increase of the phase noise of the comb modes, as the comb mode number, counted from the wavelength of a pump cw laser, increases. In addition, we measure the relative phase noise between the comb modes, showing less influence of the phase noise of pump cw lasers by comparing soliton combs generated from pump cw lasers with low and large phase noise.

A fluorous synthetic receptor that recognizes perfluorooctanoic acid (PFOA) via fluorous interaction obtained by molecular imprinting.

A polymeric sorbent selective for perfluorooctanoic acid (PFOA) was synthesized by a molecular imprinting technique using a fluorous monomer and cross-linker, and assessed chromatographically, suggesting that the fluorous imprinted polymer recognizes PFOA via hydrogen bonding and fluorine-fluorine interaction.

Synthetic cinchonidine receptors obtained by cross-linking linear poly(methacrylic acid) derivatives as an alternative molecular imprinting technique.

A molecular imprinting approach to construct synthetic receptors was examined, wherein a linear pre-polymer bearing functional groups for intermolecular interaction with a given molecule is cross-linked in the presence of the molecule as a template, and subsequent removal of the template from the resultant network-polymer is expected to leave a complementary binding site. Poly(methacrylic acid) (PMAA) derivatized with a vinylbenzyl group as a cross-linkable side chain was utilized as the pre-polymer for the molecular imprinting of a model template, (-)-cinchonidine. Selectivity of the imprinted polymer was evaluated by comparing the retentions of the original template, (-)-cinchonidine and its antipode (+)-cinchonine in chromatographic tests, exhibiting a selectivity factor up to 2.4. By assessment of the imprinted polymers in a batch mode, a dissociation constant at 20 degrees C for (-)-cinchonidine was estimated to be K (d) = 2.35 x 10(-6) M (the number of binding sites: 4.54 x 10(-6) mol/g-dry polymer). The displayed affinity and selectivity appeared comparable to those of an imprinted polymer prepared by a conventional monomer-based protocol, thus showing that the pre-polymer, which can be densely cross-linked, is an alternative imprinter for developing template-selective materials. (-)-Cinchonidine-imprinted polymers were prepared and assessed using the pre-polymers bearing different densities of the vinylbenzyl group and different amounts of the cross-linking agent to examine the appropriate density of the cross-linking side chain that was crucial for developing the high affinity and selectivity of the imprinted polymers.