Analytical Treatment of Parametric Effects in a Ring Resonator

A novel system of a simultaneous short-wave and millimeter-wave generation using a soliton pulse within a nano-waveguide is proposed, whereas the broad spectrum of optical output can be generated. By using the suitable parameters, for instance, input soliton power, coupling coefficients, and ring radii, the short-wave and millimeter-wave output signals can be simultaneously generated and filtered in a single system. Such a system consists of two microring resonators and a nanoring resonator that can be integrated to be a single system. Initially, the large bandwidth signal is generated by using a soliton pulse within a Kerr-type nonlinear medium, whereas the signals with broad bandwidth or wavelength can be generated. Results obtained have shown the potential of using the technique for a broad light spectra generation, where the required filtering signals are allowed to form the simultaneous up-link and down-link conversion using two different frequency (wavelength) carriers within a single system.

We propose a new optical system that can be used to form the multi soliton pulses within the micro ring resonators. The system consists of two micro ring resonators and an add/drop multiplexer that can be integrated into a single system. The large bandwidth signal is generated by using a soliton pulse propagating in a Kerr type nonlinear medium. The tuned soliton pulses in either spatial or temporal modes are obtained by using the add/drop multiplexer. Results obtained have shown that the multi soliton pulses can be localized coherently within the micro ring waveguide. This is shown that the generation of the multi soliton pulses within the micro ring resonator is achieved, which is available for long distance communication with dense wavelength division multiplexing (DWDM). A significant increase in channel number and spacing is obtained, and the large free spectrum range (FSR) of 600 pm is achieved. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1374–1377, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24299

The authors present a silicon-on-insulator single ring resonator with a free spectral range equal to 47nm, which is the widest known value for this type of resonators. The ring radius is 2μm and is the smallest ring resonator ever reported, achieving experimentally such a wide spectral range. For this ring resonator, the authors demonstrate the quality factor to be equal to 6730±60. They thermally tune the resonant wavelength with 0.11nm∕°C, thus showing the ring resonator as an attractive component for on-chip ultracompact photonic add/drop filters and switches.

Super DWDM light source generation for personnel health data and security camera

We deduce equations to calculate coupling coefficients of diamond micro-ring resonators. The equations can be used universally at any wavelength but not limited to the transmission peaks/valleys, and can be adapted with triangular cross-sections and tapered waveguides. Consequently, we build three models in accordance to different diamond processing technologies. These models deal with ring resonators with either rectangular cross sections, or triangular cross sections, or with tapered bus for triangular cross sections. The calculated coupling coefficients can be well fitted by exponential decay functions of gap d. Due to geometrical limitations, triangular-cross-sectional diamond resonators are shown to have much smaller (factor 20) coupling coefficients than those of rectangular-cross-sectional resonators. A tapered bus is shown to be beneficial to increase the coupling coefficient. Besides the calculation of coupling coefficients, the method presented in the paper can also be used to calculate the bending loss of micro-ring resonators, as a complement to the existing methods.

Characteristics optimization in single and dual coupled silicon-on-insulator ring (disk) photonic biosensors

A new concept of white light generation using a nano-waveguide for the solar radiation collection use

Optical ring or disk resonators can trap traveling optical waves in a closed path, for example, in a waveguide loop or silicon disk cavity. Energy can be added to or extracted from the cavity with the help of waveguide directional couplers. Ring/disk resonators can be fabricated with high quality factor (Q) in diverse material platforms. The high Q of these devices makes them very sensitive to small variations in (i) optical path length (phase), (ii) optical path loss (attenuation), and (iii) coupling coefficient. Any change in the optical path length can cause a shift in the resonance frequency of the ring. Whereas, the change in path loss and coupling coefficient can lead to a change in the Q of the resonator. The micro or nano opto-electro-mechanical systems (MOEMS/NOEMS) provide unique flexibility with a wide change in the tuning parameters. The tuning is obtained by either (i) displacement of the detached parts or (ii) strain in the waveguide/disk. Displacement of a structure detached from the ring/disk closer to the evanescent field can increase the effective refractive index or attenuation. The displacement of a waveguide in the directional coupler altering the gap can change the coupling coefficient. Strain from various sources can lead to refractive index (phase) and absorption changes, in addition to changing the dimensions. Mechanical, electrothermal, piezoelectric, electrostatic, and magnetic actuators have been demonstrated with MOEMS. Mechanical latching has been used to achieve nonvolatile tuning. Multi-beam supported, freestanding, and diaphragm supported structures have shown applications in sensing, optical switching, and energy conversion. MOEMS/NOEMS has recently been shown to provide the desired properties of modern sensors and photonic integrated circuits (PICs) such as low optical power consumption, high resolution, wide tuning range, low complexity, small footprint, low actuator power consumption, and compatibility with standard fabrication technologies. This chapter will start by briefly covering the basics of MOEM tuned ring/disk resonators. Then, the current technology aspects such as tuning mechanism, actuator types, and the fabrication technology will be discussed along with recent innovations. Furthermore, the evolution into NOEMS with specialized applications and materials will be emphasized along with emerging trends.

We firstly propose the simple system of an attosecond light pulse generation by using a soliton pulse circulating in the integrated micro ring devices. The ultra short pulse in the atto scale regime and its beyond can be easily generated. Simulation results obtained have shown that the generation of a very narrow pulse and sharp tip is achieved. In principle, light pulse known as soliton pulse is input into a three stage micro ring resonators, where the ring radii are within the range from 5-15 microns. With some selected parameters such as ring radius, coupling ratio and nonlinear refractive index, the attosecond pulse is generated and achieved. The potential applications of using such a narrow pulse for new generation optical lithography, high density CD writing, high resolution interferometer, surface roughness and high speed optical computing, quantum computing are discussed.

In this paper, a class of dual-band ring-resonator bandpass filters is proposed based on a single ring resonator. As its most distinctive feature, two pairs of first- and second-order degenerate resonant modes in a ring resonator are simultaneously excited, resulting in a compact dual-mode dual-band bandpass filter with two transmission poles in both passbands. Firstly, two capacitors or parallel-coupled lines are placed at two nonorthogonally excited positions along a ring resonator in order to excite the two first-order degenerate modes and create multiple transmission zeros. Next, a set of perturbations is introduced on the ring to excite the two second-order degenerate modes. In our design, two excitation positions are first placed with between 45°- and 135°-separation on a ring. Simulations show that, with a proper arrangement of the excitation angle, two transmission poles in the first passband can be excited and more transmission zeros can be generated. Four and eight open-circuited stubs are loaded symmetrically along the ring, resulting in synchronous excitation of two poles in the second passband. Of the two designed filters with 135°- and 45°-separation, the one with 45° exhibits much better out-of-band performance with three additional transmission zeros at frequencies lower than the first passband, between the two passbands and higher than the second passband. Finally, two filter prototypes are fabricated and their measured results are found to be in good agreement with theory.

A detailed analysis of fundamental tradeoffs between ring radius and coupling gap size is presented to draw realistic borders of the possible design space for microring resonators (MRRs). The coupling coefficient for the ring-waveguide structure is estimated based on an integration of the nonuniform gap between the ring and the waveguide. Combined with the supermode analysis of two coupled waveguides, this approach is further expanded into a closed-form equation that describes the coupling strength. This equation permits to evaluate how the distance separating a waveguide from a ring resonator, and the ring radius, affect coupling. The effect of ring radius on the bending loss of the ring is furthermore modeled based on the measurements for silicon MRRs with different radii. These compact models for coupling and loss are subsequently used to derive the main optical properties of MRRs, such as 3-dB optical bandwidth, extinction ratio of resonance, and insertion loss, hence identifying the design space. Our results indicate that the design space for add-drop filters in a wavelength division multiplexed link is currently limited to 5–10 $\mu$ m in radius and gap sizes ranging from 120 to 210 nm. The good agreement between the results from the proposed compact model for coupling and the numerical FDTD and experimental measurements indicate the application of our approach in realizing fast and efficient design space exploration of MRRs in silicon photonic interconnects.

We propose a novel system of a broadband source generation using a common soliton pulse (i.e. with center wavelength at 1.55 ?m) propagating within a nonlinear microring and nanoring resonators system. A system consists of a micro ring resonator system incorporating an add/drop filter, whereas the large bandwidth signals can be generated, stored and regenerated within the system. By using the appropriate parameters relating to the practical device such as micro ring radii, coupling coefficients, linear and nonlinear refractive index, we found that the obtained multi soliton pulses have shown the potential of application for dense wavelength division application, whereas the different center wavelengths of the soliton bands can be obtained via the add/drop filter, which can be used to increase the channel capacity in communication network.

In this paper, we proposed high speed 8PSK optical modulator using silicon/electro-optic polymer hybrid coupled ring resonators (Si/EO-PHCRR). The design comprises of two coupled ring resonator (CRRs) that has a primary and secondary rings and a single ring resonator (SRR), which acts as a delay line. The two CRRs are arranged in parallel within the two branches of the Mach–Zehnder interferometer (MZI), collectively producing a quadrature phase shift keying (QPSK) at the output terminal of MZI. The SRR is also configured in series with MZI and functions as an angle modulator, essentially serving as a π/4 phase shift modulator that operates based on the bit pattern applied to it. The CRR ensures a high energy storing capability that enhances the modulation efficiency and enables relatively high extinction ratio with better design flexibility and negligible losses. Thus, in this system, a 3 dB modulation bandwidth f 3dB = 51.14 GHz is realized with the moderate quality factor of Q = 3,839 and tunability of the modulator is found to be 723.65 pm/V with an extinction ratio of 29 dB. Also, the performance analysis of the modulator have be done at the bit rate of 150 Gbps and resulted in a high optical signal to noise ratio (OSNR) of 17.98 dB with a BER of 10−9 at the span of 100 Km dispersion shifted fiber.

Astronomical instrumentation is traditionally costly, large, and alignment-sensitive owing to the use of bulk optics. The use of integrated photonic devices in astronomical instrumentation can mitigate such drawbacks in certain applications where high light throughput and spectral bandwidth are less crucial. In this work, we present an ultra-compact carbon dioxide detection scheme using a single silicon waveguide ring resonator. The comb-like absorption line spectrum of CO2 around 1580 nm wavelength can closely match the comb spectrum of an appropriately designed ring resonator. By actively correlating such a ring spectrum with the CO2 absorption lines, a specific detection signal can be generated. We design the free spectral range of a ring resonator to match the absorption line spacing of carbon dioxide lines in the range from 1575 to 1585 nm. Using thermo-optic modulation, the ring resonator drop or through port transmission spectrum can be shifted back and forth across the incoming CO2 light spectrum, resulting in a modulated signal with an amplitude proportional to the CO2 absorption line strength. Furthermore, high frequency modulation and lock-in detection can result in a significant improvement in the signal to noise ratio. We demonstrate that such a device can provide real-time carbon dioxide detection for applications in ground- and satellite-based astronomy, as well as remote atmospheric sensing, in a compact package. In future work, such a sensor can be adapted to a range of gases and used to determine radial velocities and compositional maps of astronomical objects.

Effect of photoconductivity and dielectric constant of the photorefractive materials on two-beam coupling gain and phase-shifts for a single unidirectional photorefractive ring resonator