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This article reports an implementation of a microsphere-based optical frequency comb (OFC) generator for substitution of individual laser arrays and simulates wavelength division multiplexed passive optical network (WDM-PON) based on this OFC generator. Our proposed generator is built based on silica microsphere, barely studied for fiber optical communication systems, and is a promising solution with photonic integration capability. Kerr OFC as a multiple light source containing more than 20 spectral carriers in the fundamental mode family in the C-band and beyond is demonstrated experimentally. Four of these OFC generator carriers with the highest peak power are studied in simulated 4-channel 393 GHz spaced WDM-PON. Additionally, we show this OFC as a source of optical carriers capable of providing data transmission over most utilized fiber types in modern optical communication systems, namely, single-mode fiber (SMF), non-zero dispersion-shifted fiber (NZ-DSF), and cut-off shifted fiber (CSF). We show through the simulations that error-free data transmission is possible, providing a total transmission capacity of 40 Gbit/s by using four OFC generated carriers.

Optical frequency combs generated in whispering gallery mode microresonators are in high demand for basic science and a large number of applications including telecommunication systems and quantum optics. Here, we study experimentally and theoretically optical frequency comb generation in a silica microsphere with a zero dispersion wavelength near $1.55~\mu \text{m}$ pumped by a continuous wave laser widely tunable in the C-band. We considered the optical frequency comb generation for a pump wavelength in a normal dispersion region, in a low anomalous dispersion region, and very close to the zero dispersion wavelength. Kerr-assisted and Raman-assisted (Stokes) combs as well as anti-Stokes combs emerging due to the four-wave mixing between the Kerr and Raman combs are attained in experiments. The mechanisms of producing individual peaks of optical frequency combs are verified in numerical simulations. A 270-nm optical frequency comb covering the telecommunication E-, S-, C-, L-, U-bands and further up to $1.7~\mu \text{m}$ is also demonstrated.

High nonlinearity optical devices are of interest for compact, low power devices. Whispering gallery mode (WGM) microresonators offer strong nonlinear optical responses due to high quality factors ...

Among the different types of photonic sensor devices, optical whispering gallery mode resonators (WGMRs) have attracted interest due to their high level of sensitivity, small size, and ability to perform real-time temperature measurements. Here we demonstrate the applicability of temperature measurements using WGMR in both air and liquid environments. We also show that WGMR allowed measurements of the refractive index variations in an evaporating glucose–water solution droplet. The thermal tuning of WGMR can be reduced by coating WGMRs with a thin layer of polymethyl methacrylate (PMMA). Dip-coating the silica microsphere multiple times significantly reduced the resonance shift, partially compensating for the positive thermo-optical coefficient of silica. The shift direction changed the sign eventually.

Optical frequency combs (OFCs) generated in microresonators with whispering gallery modes are demanded for different applications including telecommunications. Extending operating spectral ranges is an important problem for wavelength-division multiplexing systems based on microresonators. We demonstrate experimentally three spectrally separated OFCs in the C-, U-, and E-bands in silica microspheres which, in principle, can be used for telecommunication applications. For qualitative explanation of the OFC generation in the sidebands, we calculated gain coefficients and gain bandwidths for degenerate four-wave mixing (FWM) processes. We also attained a regime when the pump frequency was in the normal dispersion range and only two OFCs were generated. The first OFC was near the pump frequency and the second Raman-assisted OFC with a soliton-like spectrum was in the U-band. Numerical simulation based on the Lugiato–Lefever equation was performed to support this result and demonstrate that the Raman-assisted OFC may be a soliton.

For the quantum optomechanics research, the mechanical oscillator needs to be cooled to ground state in a cryostat or vacuum chamber, which can also improve the Q factors of the mechanical modes. However, stable 3D optical stages are required to hold the microresonator-taper coupling system to keep and adjust the air gap between them and, thus, give rise to experiment difficulties in a relatively small vacuum chamber or cryostat. To address this issue, an efficient method to package a coupled silica microsphere and tapered fiber system is proposed and demonstrated experimentally. For the purpose of optomechanical studies, high-quality-factor optical and mechanical modes are maintained after the packaging process. For the mounted microsphere, the coupling system is more stable and compact and, thus, is beneficial for future studies and applications based on optomechanical interactions. Especially, the packaged optomechanical system, which is tested in a vacuum chamber, paves the way toward quantum optomechanics research in cryostat.

Here we studied theoretically and experimentally the thermal frequency shift of whispering gallery modes (WGM) in silica and tellurite spherical microresonators. Temperature distributions and corresponding shifts of WGMs were calculated. The shift obtained in a silica microsphere generating optical frequency comb (OFC) with a width of >300 nm and independent estimates showed that thermal and Kerr effects made a comparative contribution. For a tellurite microsphere without OFC generation, the thermal effect dominated.

Two types of optical pressure sensors with silica microspheres are proposed. The size effect of optical silica microsphere pressure sensors is studied by using a single-wavelength laser beam and polarimeters. The silica microspheres with diameters of 1.0 μ m, 1.5 μ m and 2.0 μ m are prepared on garnet substrates by a self-assembly method. The pressure and the optical properties of the silica microspheres are measured by a resistance strain sensor and Thorlabs Stokes polarimeters as a function of the external direct current (DC) voltage. The optical silica microsphere sensor in transmission mode is suitable for pressure measuring. The results show that the pressure increases, while the diameter of the silica microspheres decreases. The maximum internal pressure can reach up to 7.3 × 107 Pa when the diameter of the silica microspheres is 1.0 μ m.

Optical whispering gallery mode microresonators with controllable parameters in the telecommunication range are demanded for diverse applications. Controlling group velocity dispersion (GVD) in microresonators is an important problem, as near-zero GVD in a broad wavelength range could contribute to the development of new microresonator-based light sources. We demonstrated theoretically near-zero dispersion tailoring in the SCL-band in combination with free-spectral range (FSR) optimization for FSR = 200 GHz and 300 GHz in silica glass microspheres with micron-scale germanosilicate coating. As an illustration of a possible application of such a GVD, we also performed a theoretical study of degenerate four-wave mixing (FWM) processes in the proposed microresonators for pumping in the SCL-band. We found that in some cases the generation of two or even three pairs of waves–satellites in a FWM process is possible in principle due to the specific GVD features. We also determined optimal microresonator configurations for achieving gradual change in the satellite frequency shift for the pump wavelengths in the SCL-, S-, CL-, C-, and L-bands. The maximum obtained FWM satellite tunability span was ~78 THz for a pump wavelength change of ~30 nm, which greatly exceeds the results for a regular silica microsphere without coating.

We demonstrate ultralow-threshold neodymium-doped silica microsphere lasers on a silicon chip with lasing wavelengths of ~900 nm and ~1060 nm. Neodymium-doped microsphere cavities are fabricated with a series of doping concentrations using silica sol–gel films. Experimentally, we observe single-mode lasing emissions from the high-Q microsphere cavities with a threshold of as low as 1.2 µW.

We propose and experimentally demonstrate a microwave photonic (MWP) notch filter based on a silica microsphere cavity. By using a high-Q-factor (∼1e7) cavity with a diameter of 132 um, the filter bandwidth can be easily decreased to 15 MHz in terms of simple fabrication and flexible coupling. Then we use the advanced modulation technique based on a dual parallel Mach–Zehnder modulator to further improve peak rejection (PR). The experimental results show that the MWP notch filter with its PR beyond 55 dB and frequency tunability range over 8 GHz has been achieved in combination with double-sideband modulation. To the best of our knowledge, this is a record for PR and bandwidth considered simultaneously for an MWP filter based on silica microcavities. Thus, the proposed MWP filter will be useful in the fields of microwave photonic signal processing, radar systems, etc.

Optical frequency combs (OFCs) generated in microresonators with whispering gallery modes are attractive for different applications and basic science. The effects associated with Raman nonlinearity are constantly being discovered and investigated experimentally and theoretically expanding the capabilities of microresonator OFCs. Here we obtain experimentally Raman-assisted nested OFCs in two different mode families with soliton-like (sech2-shape) spectral envelopes for each mode family in a silica microsphere. By comparing the experimental frequencies of spectral harmonics with the calculated eigenfrequencies we verified that the generated OFC with a larger bandwidth corresponds to the fundamental TE mode family, and the OFC with a smaller bandwidth to the TM mode family. We report the regime when the pump wavelength (without an OFC nearby) is in the normal dispersion region and Raman-assisted OFCs are generated in the anomalous dispersion region.

Optical frequency comb (OFC) generators based on whispering gallery mode (WGM) microresonators have a massive potential to ensure spectral and energy efficiency in wavelength-division multiplexing (WDM) telecommunication systems. The use of silica microspheres for telecommunication applications has hardly been studied but could be promising. We propose, investigate, and optimize numerically a simple design of a silica microsphere-based OFC generator in the C-band with a free spectral range of 200 GHz and simulate its implementation to provide 4-channel 200 GHz spaced WDM data transmission system. We calculate microsphere characteristics such as WGM eigenfrequencies, dispersion, nonlinear Kerr coefficient with allowance for thermo-optical effects, and simulate OFC generation in the regime of a stable dissipative Kerr soliton. We show that by employing generated OFC lines as optical carriers for WDM data transmission, it is possible to ensure error-free data transmission with a bit error rate (BER) of 4.5 &times, 10&minus, 30, providing a total of 40 Gbit/s of transmission speed on four channels.

We demonstrate experimentally a silica microresonator-based single-mode Raman laser tunable in the U-band and beyond. The Stokes wavelength is tuned in the 1631–1685 nm range when tuning a C-band pump laser in the 1520–1570 nm range. We also demonstrate switching between Raman lasing modes which corresponds to “jumps” by 2 or 3 whispering gallery modes (WGMs) while sweeping the pump laser near a certain WGM (without pump “jumps” between WGMs). In addition, four-wave mixing (FWM) leading to single mode anti-Stokes wave generation in the E-band near 1450 nm is obtained when the pump wavelength is near the microresonator zero dispersion wavelength (ZDW) and the phase matching condition for the pump, Stokes, and anti-Stokes waves is satisfied.

We demonstrate a compact in-fiber integrated microresonator based on a silica microsphere and microstructure fiber. Whispering-gallery-modes (WGMs) are effectively excited through evanescent field coupling between the silica microsphere and one of the input tube waveguides of negative curvature fiber. The WGM spectrum with the Q-factor of ∼2.56 × 103 and the extinction ratio of ∼15.2 dB is achieved. The transmission spectra evolution for 5 h reveals the long-term stability of WGM excitation. The experimental results indicate that the in-fiber integrated resonator has the advantages of high stability, high integration, robustness, alignment-free assembly structure, and low cost, motivating potential applications in the lab-in-fiber platform.

In an optomechanical resonator, the optical and mechanical excitations can be coherently converted, which induces a transparency window for a weak probe laser beam. Here, we report an experimental study of transient optomechanically induced transparency (OMIT) using the silica microsphere with the breathing modes. The transient OMIT behavior obtained are in good agreement with theoretical calculations. In addition, the coherent interconversion between optical and mechanical excitations that can be used for light storage and readout has also been studied here. Our experimental results indicate that the light storage is closely related to the process of OMIT, and the photon-phonon conversion can be further applied to optical wavelength or optical mode conversion.

Here we report an active microresonator by integrating a thin layer of all-inorganic CsPbBr 3 nanocrystals (NCs) to a silica microsphere. We also demonstrate the transition from spontaneous emission to stimulated emission (SE) of CsPbBr 3 with varying pump power. Further lasing is expected by improving the fabrication technology. Our configuration may provide a route to low threshold and compact lasers, and find applications in sensing.

In this work, we demonstrated the precise measurement and monitoring of superconductor temperature using an optical whispering-gallery mode sensor for the first time. A silica microsphere was placed into contact with a high-temperature DI-BSCCO superconductive tape (~10 cm long) to characterize superconductivity versus temperature. The electrical conductivity was measured by the 4-point probe method. The sensitivity of the WGM sensor was determined to vary from 3.6 pm K−1 to 5.5 pm K−1 when the temperature rose from 105 K to 150 K, which agrees well to analysis. The present instrument is small in size, fast in response, low in cost, and high in accuracy and resolution. The measurements were compared with factory specified results obtained from costly and bulky facility and an excellent agreement was found.

In this research, we present a packaged add–drop filter composed of a silica microsphere resonator and a strongly coupled optical microfiber coupler. A one-step fabrication process using UV curable epoxy is shown to stabilize the microsphere resonator coupled to the microfiber coupler, which is used as add and drop ports. A high Q-factor of 3×107 is obtained at around 780 nm from the packaged microspheres coupled with the microfiber coupler in the add–drop configuration.

The three-dimensional finite-difference time-domain method was used to demonstrate a novel structure for coupling whispering gallery mode (WGM) with surface plasmons (SPs). As for this structure, a micrometer-sized optical resonator composed of a silver film coated on a silica microsphere containing apertures is set on a glass substrate. The SPs couple with higher-order WGM, and their intensity is clearly enhanced by this structure.

We have studied the Kerr effect in silica microspheres and demonstrated compensation of the Kerr effect for transient optomechanically induced transparency (OMIT). Due to the Kerr effect of the temporal strong driving pulse, an asymmetric transparency dip is observed during the transient OMIT experiment when the laser frequency is locked at one mechanical frequency, ω(m), below the whispering gallery mode resonance using a weak locking pulse. For compensation of the Kerr effect, we lock the laser at a lower frequency and show the symmetric transparency window. These results are important for studying photon-phonon interconversion, especially in systems with strong driving power.

We report the enhancement of light extraction efficiency of InGaN-based blue light emitting diodes by using a surface light-scattering layer. A number of SiO2 microspheres embedded into a ZrO2 thin layer played a role of a light-scattering medium. Coating the light-scattering layer on device surface, the inter- ference fringes of electroluminescence (EL) spectra were eliminated and the EL intensity around 440–450 nm was increased by a factor of 1.3. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We have reported an experimental demonstration of Brillouin-scattering-induced transparency (BSIT) in a silica microsphere. Because of the phase-matching requirement, the non-reciprocal light storage based on the BSIT process is also observed in our experiment.

Whispering Gallery Modes (WGMs) microresonators continue to receive an even greater interest for investigation in many fundamental processes (e.g.: quantum electrodynamics or non–linear optics) and in more applied fields of photonics (e.g.: filters, microlasers and chemical/biological sensing), due to their high Q—factors, small mode volumes and long photon storage times. Here we present an overview on the main results obtained in our Labs about the implementation of these optical microcavities as suitable platform for sensing and biosensing applications.

We demonstrate the tuning of high- Q optical whispering-gallery modes in a fused silica microsphere by applying mechanical strain. The measured total tunability is over 0.3 nm in the near-infrared band, with the undercoupled quality-factor being Q >1×10 8 . The tunability of mode frequencies in this high- Q solid-state microcavity expands its applicability in quantum optics and photonics.

In this paper, we investigate theoretically and experimentally a silica micro-sphere resonator with the diameter of 225 μm. We undertake the detailed comparisons of the free spectral range (FSR) values obtained from both the experimental results and numerical simulations.

We observed optomechanical oscillations at 384-kHz by immersing a silica microsphere in an aqueous environment. Despite of high dissipation, the device displays a laser threshold power of 0.98-mW and a mechanical Q of 1,648.

We have fabricated an active add-drop filter (ADF) using an erbium-ytterbium co-doped microsphere resonator and have achieved 25-fold Q-enhancement, 4-fold increase in efficiency and crosstalk of 2%. This ADF provides equal add and drop efficiencies.

Self-stimulated Raman lasers have attracted more and more interest, because they have no need of additional Raman device, and they are compact in structure and also economical in cost. Self-stimulated Raman lasers are always emitted from crystalline mediums such as Nd3+:KGd(WO4)2, Nd3+:PbWO4 that are commonly used as laser host materials and proved to be available Raman-active mediums. The Nd3+ doped crystals possess high stimulated emission cross-section for laser emission and high Raman gain coefficients for Raman transitions, but the required pump powers (typically hundreds of milliwatts) are large in those experiments.The whispering-gallery mode (WGM) of silica microsphere cavity has achieved the highest Q factor (8×109) to date. The high Q factor and small mode volume make it possible to realize a resonant buildup of high circulating optical intensities, thereby drastically reducing the threshold powers for laser oscillation and stimulated nonlinear process. The coupler with optical fiber taper allows the excitation of WGMs with ultralow coupling loss, which significantly improves the overall efficiency to produce stimulated Raman laser. In this paper, we report the observation of ultralow threshold self-stimulated Raman laser operating in an Nd3+ doped silica microsphere, and the wavelength range can be extended to O-waveband 1143 nm.A high Q microsphere is fabricated with a thin Nd3+ doped silica layer covered by sol-gel method, in which smooth surface is formed by electrical arc-heating. An optical taper fiber is employed to couple the 808 nm laser into Nd3+ doped microsphere (NDSM) to form whispering gallery mode, which acts as the pump light. Based on 4f electron of neodymium ion transmission and optical oscillation in microsphere, the stimulated laser with a wavelength band of 1080 nm-1097 nm is excited. Due to high power density of the excited laser near the surface of orbit in microsphere, the first order self-stimulated Raman laser with a wavelength range of 1120-1143 nm is stimulated in the high Q microsphere. In a theoretical model, the formulas for calculating the output power and the threshold power of the oscillation laser and the self-stimulated Raman scattering are derived. In experiment, we succeed in getting single-mode and multi-mode laser oscillation due to the 4f layer electron transitions of Nd3+ ions, pumped by 808 nm laser. The results show that the NDSM emits a typical single-mode output laser at 1116.8 nm with a pump power of 8.33 dBm, also the relationship between the 1116.8 nm output power and the pump power with a threshold pump power of 3.5 mW. The multi-mode laser spectrum dependent on the microsphere morphology characteristics is observed, which varies by changing the couple position of the optical fiber taper with microsphere. The characteristics of the laser are discussed including the output power, threshold power, spectral line width, side-mode suppression ratio, etc. The NDSM will have many potential applications in new compact lasers. It is beneficial to wavelength converter and optical amplifier in O band.

We propose and experimentally demonstrate a tunable microwave photonic notch filter with a megahertz order bandwidth based on a silica microsphere cavity coupled by an optical microfiber. The silica microsphere with a quality factor of hundreds of millions offers a full width at half-maximum bandwidth down to the order of megahertz in the transmission spectrum. Due to the coupling flexibility between the microcavity and the optical microfiber, the bandwidth and suppression ratio can be tuned and optimized to get a rejection ratio beyond 30 dB. The tunability of over 15 GHz is also achieved. To the best of our knowledge, this single-stopband microwave photonic filter has the narrowest bandwidth filter that has ever been experimentally demonstrated. This microwave photonic notch filter shows distinct advantages of high selectivity, compactness, flexibility, and low insertion loss.

Optical microcavities provide an intriguing platform for the development of low threshold microlasers based on nonlinear effects. Long photon lifetimes within the cavity translate to high circulating optical intensities, thereby reducing the lasing threshold. It is therefore possible to create lasers that can operate in complex environments. In the present work, we use a silica microsphere to demonstrate a cascaded Raman microlaser that operates in air and buffer with the first emission peak around 800 nm in both environments. As expected, the threshold in air is significantly lower than in buffer.

We report an experimental demonstration of storing an optical pulse as a mechanical excitation in a silica microsphere. The storage lifetime is determined by the relatively long damping time of the mechanical excitation.

We experimentally characterize the Q-factor (>108) in silica microsphere by the PMMA coating. The Q-factor of microsphere with deposited QDs is increased after the coating which draws the maximal field outside and increases the interaction.

We have achieved low threshold lasing of self-assembled InAs/GaAs quantum dots coupled to the evanescent wave of the high-$Q$ whispering gallery modes of a silica microsphere. In spite of high temperature and $Q$-spoiling of whispering gallery modes due to diffusion and refraction on the high index semiconductor sample, room temperature lasing is obtained with less than 100 quantum dots. This result highlights the feasibility and interest of combining self-assembled quantum dots and microspheres in view of cavity-quantum electrodynamics experiments., Comment: To be published in Optics Express

We experimentally demonstrate controlled polarization-selective phenomena in a whispering gallery mode resonator. We observed efficient ($\approx 75 %$) polarization conversion of light in a silica microsphere coupled to a tapered optical fiber with proper optimization of the polarization of the propagating light. A simple model treating the microsphere as a ring resonator provides a good fit to the observed behavior., RevTeX4, 7 pages, 4 figures. Revised version, added 1 figure

We introduce a definition of group velocity for a system with a discreet spectrum and apply it to a linear resonator. We show that a positive, negative, or zero group velocity can be obtained for light propagating in the whispering gallery modes of a microspherical resonator. The associated group delay is practically independent of the ring-down time of the resonator. We demonstrate "stopped light" in an experiment with a fused silica microsphere.

By combining bio-recognition using bio-nano-sensors with the transduction capability of resonant dielectric micro-cavities, we demonstrate the specific identification of protein and DNA. This is accomplished through the spectroscopy of a microcavity as molecular adsorption takes place on its functionalized surface. A surprising aspect is that this sensing paradigm is not only ultra-sensitive but also provides a measure of molecular weight and the thickness of molecular monolayers on the microcavity surface. *In New Developments in Optics and Related Fields: Modern Techniques, Materials and Applications, (Kluwer Publishers, 2006, in press).

Irradiating silica microspheres, on a silica or glass surface, with single, high-energy, laser pulses from a KrF excimer laser, has generated a wealth of different micron and sub-micron, topological patterns in the substrate. Optical surface profilometry has been used as the experimental technique to study the patterns formed. Comparison of the experimental results with theoretical results from sophisticated models developed by Lukyanchuk and co-workers, and Arnold and co-workers is presented.

Cavity Q of silica microsphere with nanocrystal silicon active layer is investigated. Q factor of up to 8/spl times/10/sup 5/ is observed, and loss due to nc-Si is identified as not dominating the loss mechanism.

We report the observation of optomechanical oscillation by immersing a silica microsphere in liquid. Due to the ultra high quality factor of the microsphere in the aqueous environment, sufficient optical force was established to quiver the microsphere at a pump laser power around 1 mW.

Optical microsphere-resonator based wavelength-dropping and acceleration sensing devices are presented. Both components are integrated on SPARROW waveguide coupler chips.

We demonstrate a low-threshold microsphere laser on a silicon chip, fabricated from erbium-doped silica sol–gel film. Single-longitudinal mode lasing emission is observed from a 37 μm diameter microsphere cavity with an erbium ion concentration of 2 × 1019 cm−3. The measured lasing threshold of the silica microsphere laser is as low as 4.8 μW.

In this letter, we show how organic molecular waveguides of 1,5-diaminoanthraquinone molecules can be grown on a silica microsphere to obtain microsphere-coupled organic waveguides (MOWs). Using such MOWs, we remotely excite and detect whispering gallery modes (WGMs) of the attached microsphere. Interestingly, these WGMs showed mode-splitting and mode-mixing due to broken azimuthal symmetry of the microsphere. Furthermore, the waveguiding characteristics of MOWs showed a quadrupole intensity pattern as a function of input polarization. The presented geometry can be an excellent test-bed to study fundamental aspects of coupled resonant systems, and their properties can be harnessed in nano- and bio-photonics.

An evanescently coupled optomechanical system is developed, in which a SiN nanomechanical oscillator couples to the evanescent field of whispering gallery optical modes in a slightly deformed silica microsphere. The evanescent optomechanical coupling length varies strongly along the whispering gallery optical path, with the maximum coupling length nearly three times that of a regular optical resonator. The deformed resonator also allows efficient free-space evanescent excitation of whispering gallery optical modes. These unique features enable a relatively simple and robust implementation of evanescently coupled optomechanical systems.

High-quality-factor microspheres with smooth surface are fabricated through surface tension by heating and fusing a single tapered fiber using arc of electrodes discharge. Stimulated Raman scattering of the third order nonlinear phenomena of microspheres with high power density whispering gallery modes was studied by coupling 976 nm laser into microspheres through tapered fiber as evanescent wave. The total six cascaded Raman lasers were observed in the experiment. At each order, single longitudinal mode and multi longitudinal mode Raman lasers were observed. The Raman laser at around 1200 nm was measured with pump power less than 582.6 μW. The sixth-order Raman laser at around 1287.04 nm was observed when pump power is 3.014 mW.

We report on the realization of high-quality silica optical microcavities on a chip. We show that a precise control of radii of both silica disk and silicon pillar defines the shape of molten microresonators from microtoroids to microspheres. These last ones advantageously combine small mode volumes in structures of very small radii (5

We show how a controlled phase gate, induced by adiabatic passage of dark states, can be implemented with the nitrogen-vacancy defects in nanocrystal coupled to the optical whispering gallery mode in a silica microsphere cavity. The gate presented is robust to the fluctuations of the experimental parameters compared to the dynamical and geometric phases gates. The feasibility of this scheme is characterized by exact numerical simulations that incorporate various sources of experiment noise. The results demonstrate the practicality by way of current experimental technologies.

This Erratum corrects an error from an earlier Letter [Opt. Lett. 34, 3740 (2009)] in the calculation of the mode frequencies of a silica microsphere for angular mode number l=0.

We analyze the process of cascaded four-wave mixing in a high-Q microcavity and show that under conditions of suitable cavity-mode dispersion, broadband frequency combs can be generated. We experimentally demonstrate broadband, cascaded four-wave mixing parametric oscillation in the anomalous group-velocity dispersion regime of a high-Q silica microsphere with an overall bandwidth greater than 200 nm.