Bottle Mode Research Articles

Direct single-mode lasing in polymer microbottle resonators through surface destruction

We demonstrate an effective approach of mode suppression by simply using a tungsten probe to destroy the external neck surface of polymer microbottle resonators. The higher-order bottle modes with large axial orders, spatially located around the neck surface of the microresonator, will suffer large optical losses. Thus, excitation just with an ordinary free-space light beam will ensure direct generation of single fundamental bottle mode lasers. This method is with very low cost and convenient and can obtain high side-mode suppression factors. Our work demonstrated here may have promising applications such as in lasing and sensing devices.

Degenerate four-wave mixing in a silica hollow bottle-like microresonator.

A hollow, bottle-like microresonator (BLMR) was fabricated from a microcapillary with a nearly parabolic profile. From simulations at 1.55 μm the fundamental bottle mode is shown to be in the anomalous dispersion regime, while the conventional whispering gallery mode, confined to the center of the BLMR, is in the normal dispersion regime. Therefore, we have experimentally shown that, for a BLMR with a diameter of 102 um, degenerate four-wave mixing can only be observed by judicious selection of the tapered fiber coupling position. Dispersion tuning in such a system is also briefly discussed theoretically. BLMRs are promising devices for the implementation of sparsely distributed, widely spanned frequency combs at the telecommunications C-band.

Raman lasing in a hollow, bottle-like microresonator

We report on the fabrication of an ultrahigh-quality-factor, bottle-like microresonator from a microcapillary and the realization of Raman lasing therein at pump wavelengths of 1.55 µm and 780 nm. The dependence of the Raman laser threshold on the mode volume is investigated. The mode volume of the fundamental bottle mode is calculated and compared with that of a microsphere. Third-order cascaded Raman lasing was observed under pumping at 780 nm. In principle, Raman lasing in a hollow bottle-like microresonator can be used in sensing applications. As an example, we briefly discuss the possibility of a high-dynamic-range, high-resolution aerostatic pressure sensor.

Mode-selective lasing in high-Q polymer micro bottle resonators.

Passive and active polymer micro bottle resonators (MBRs) are fabricated. Equatorial whispering gallery modes and bottle modes are clearly identified, with highest loaded quality (Q) factor above 10(5). Lasing with threshold as low as 1 nJ/pulse is realized in active MBRs. Mode selective lasing is achieved by coupling a tapered fiber to equatorial whispering gallery modes or a group of bottle modes. The bottle mode free spectral range (FSR) is found to be about one fifth of the equatorial modes.

Hollow-bottle optical microresonators

Selective excitation of whispering-gallery and bottle modes in a robust hollow-bottle optical microresonator, fabricated from a silica microcapillary by a pressure-compensated, "soften-and-compress" method, is demonstrated. Characteristic resonance spectra of bottle modes were obtained by using a tapered fiber coupled at different locations along the hollow bottle. The spectral characteristics (Q-factor, excitation efficiency) are shown to have high tolerance to angular misalignment of the tapered fiber. In addition, introduction of localized losses on the outer surface of the resonator results in selective clean-up of the transmission spectrum and superior performance. A theoretical analysis of modal turning points and associated resonant wavelengths is used to explain the mechanism of mode-suppression and the resultant spectral cleaning.

All-optical signal processing at ultra-low powers in bottle microresonators using the Kerr effect

We present experimental results on nonlinear, ultra-low power photonics applications based on a silica whispering-gallery-mode microresonator. Our bottle microresonator combines an ultrahigh quality factor of Q > 10(8) with a small mode volume V. The resulting Q(2)/V-ratio is among the highest realized for optical microresonators and allows us to observe bistable behavior at very low powers. We report single-wavelength all-optical switching via the Kerr effect at a record-low threshold of 50 microW. Moreover, an advantageous mode geometry enables the coupling of two tapered fiber waveguides to a bottle mode in an add-drop configuration. This allows us to route a CW optical signal between both fiber outputs with high efficiency by varying its power level. Finally, we demonstrate that the same set-up can also be operated as an optical memory.

Selective excitation of whispering gallery modes in a novel bottle microresonator

Selective excitation of spheroidal whispering gallery modes and bottle modes in a robust bottle microresonator fabricated straightforwardly from a short section of optical fiber is demonstrated. Characteristic resonance spectra of long-cavity bottle modes were obtained by using a tapered fiber to excite evanescently bottle microresonator at different points along its axis. Compared to bare-fiber cylindrical resonators, the bottle microresonator results in a 35x increase of the observed Q factor.

Determination of low-molecular-mass aliphatic carboxylic acids and inorganic anions from kraft black liquors by ion chromatography

An ion chromatographic (IC) method with suppressed conductivity detection (CD) was developed and validated for the quantitative determination of several low-molecular-mass aliphatic mono- and dicarboxylic acids as their carboxylate anions together with some inorganic anions (chloride, sulfate, and thiosulfate) from kraft black liquors. To confirm the identification of some carboxylate anions which lack commercial model substances, a qualitative IC method with suppressed electrospray ionization mass spectrometry (ESI-MS) was also developed. The separations were performed on an IonPac AS 11-HC anion-exchange column operated at 25 °C within 25 min by a gradient elution with aqueous potassium hydroxide (suppressed CD in the AutoRegen mode) or sodium hydroxide (suppressed ESI-MS in the pressurized bottle mode). In the validation process a mixture of carboxylic acids and inorganic anions in aqueous media and in seven different types of wood and non-wood black liquor samples were quantitatively analyzed by IC-CD. As a result, calibration lines with correlation coefficients of 1.00 for all analytes were achieved at a concentration range from 0.05 to 105 mg L −1. In black liquor samples intra-day ( n = 6) precision values ranged from 0.9 to 5%. Day-to-day ( n 1 = 3) and intermediate precision values were less than 5% for all other compounds except sulfate and thiosulfate. The variability in the thiosulfate and sulfate results is due in large part to the oxidation of sulfide and thiosulfate, respectively. Recoveries were close to 100% with standard deviations less than 8%. Depending of the analyte, the limits of detection and quantification were, respectively, between 1 and 8 μg L −1 and between 3 and 27 μg L −1 for standard compounds in aqueous media and between 6 and 106 μg L −1 and between 14 and 148 μg L −1 for black liquor samples. These validation results clearly indicated that with respect to selectivity, linearity, limits of detection and quantification, precision, and accuracy, the IC-CD method showed good applicability in the determinations described above.