We present a novel concept of a compact, ultra fast electro-optic modulator, based on photonic crystal resonator structures that can be realized in two dimensional photonic crystal slabs of silicon as core material employing a nonlinear optical polymer as infiltration and cladding material. The novel concept is to combine a photonic crystal heterostructure cavity with a slotted defect waveguide. The photonic crystal lattice can be used as a distributed electrode for the application of a modulation signal. An electrical contact is hence provided while the optical wave is kept isolated from the lossy metal electrodes. Thereby, well known disadvantages of segmented electrode designs such as excessive scattering are avoided. The optical field enhancement in the slotted region increases the nonlinear interaction with an external electric field resulting in an envisaged switching voltage of approximately 1 V at modulation speeds up to 100 GHz.

Electro-optical modulator in a polymerinfiltrated silicon slotted photonic crystal waveguide heterostructure resonator.

A compact and high quality terahertz photonic crystal switch is proposed in silicon. The switch operates based on the self-imaging principle in multi-mode photonic crystal waveguide of triangular lattice. The finite-difference time-domain method and the plane wave expansion method are used to verify and analyze the characteristics of the proposed switch. Numerical simulation results agree well with the theoretical expectation. This kind of device is potentially important for terahertz application and might be a new breakthrough to design other kinds of photonic crystal switches.

Terahertz photonic crystal switch in silicon based on self-imaging principle

In 1987, Yablonovitch and John proposed an artificial dielectric structure known as Photonic crystals (PhCs) consisting of periodic and random variation of the refractive index to manipulate the flow of light. The photonic devices realized on PhCs can take advantage of the ability to tailor the propagation of the electromagnetic field in these structures on a microscopic scale. Besides, the devices with small footprints can be realized. In recent years, several interesting devices based on PhCs are proposed which comprises small radius bent waveguides (hereafter represented as WGs), miniaturized resonator cavities, and Y-branches, among others. These extraordinary features can lead to the development of a dense integrated circuit. However, the PhC technology is still new and there is a need to investigate this topic more extensively. In this paper, we have reviewed the most common and vital optical elements based on PhCs such as logic gates, power splitter, polarization splitter, sensors, absorbers for solar thermophotovoltaic applications and electrically pumped lasers to sum up the recent developments in this hot topic. These devices show better performance and a small footprint in comparison with conventional photonic devices.

Recent advances in photonic crystal optical devices: A review

All-optical comparators play crucial roles in all-optical data processing systems. In this paper, we proposed a novel structure for realizing an all-optical comparator, which can compare two 1-bit binary codes. For this purpose, we used three nonlinear resonant rings. The final structure has two input and three output ports. The maximum rise and fall times for the proposed structure are about 1.5 and 2 ps, respectively.

A novel proposal for all-optical 1-bit comparator using nonlinear PhCRRs

In the present paper, we study the transmission of the two-dimensional photonic crystal (PC) superellipse ring resonator. The fast growing applications of optomechanical systems lead to strong demands in new sensing mechanism in order to design the sensing elements to nanometer scale. The photonic crystal based resonator has been investigated as promising solutions because the band gap structure and resonator characteristics are extremely sensitive to the deformation and position shift of rod / cavity in PC resonators. This structure opens a single channel filter. The study is extended for tuning of channel filter’s wavelength with a temperature of this structure. The transmission of the channel filter shows a red shift with temperature linearly. This wavelength shift of the channel filter is used for the sensor application. The sensitivity for the proposed structure is found to be 65.3 pm/°C. The outstanding sensing capability renders PC resonators as a promising optomechanical sensing element to be integrated into various transducers for temperature sensing applications.

https://link.springer.com/content/pdf/10.1007%2Fs13320-017-0443-z.pdf

Novel Design of Ring Resonator Based Temperature Sensor Using Photonics Technology

We propose a new power-splitting scheme in two-dimensional photonic crystals that can be applicable to photonic integrated circuits. The proposed power-splitting mechanism is analogous to that of conventional three-waveguide directional couplers, utilizing coupling between guided modes supported by line-defect waveguides. Through the analysis of dispersion curve and field patterns of modes, the position in propagation direction, where an input field is split into a two-folded image, is determined by simple mode analysis. Based on the calculated position, a photonic crystal power-splitter is designed and verified by finite-difference time-domain computation

Photonic crystal power-splitter based on directional coupling.

We have studied the transmission characteristics of photonic crystal waveguide with two 60° bends. By moving the position of air holes, the bending section is modified. As the periodicity or the symmetry of the bending section is changed even a little, the characteristics of transmission window is modified greatly.

Filtering Characteristics of Photonic Crystal Waveguide with Bends

We present a new approach in the design of a photonic crystal bandpass filter by using waveguide bending. The bandpass filter was designed by introducing two bends with the modified geometry into the both ends of a photonic crystal waveguide. We show that such a filter exhibits step-like spectral profile in the range of 1500-1600 nm, with a maximum transmission of 100%. In contrast to the other designs proposed, the present one does not involve either insertion of small defects or control of cavity-lengths.

Use of waveguide bending as a new approach in the design of a triangular-lattice photonic crystal bandpass filter

We have designed and integrated a high density micro-ring resonator and photonic crystal waveguide array for wavelength division multiplexing (WDM) microsystem applications. First, we designed and optimized micro-ring resonators. Using the non-unitary transfer matrix method (NU-TM), we have been able to analyze the transfer characteristics of the micro-ring and micro-racetrack resonator system. The track-length dependence, which is not obvious in the unitary transfer method (U-TM) analysis, is clearly found in the NU-TM analysis. By optimizing the WDM filter characteristics such as FSR (Free Spectral Range) and cross-talk, we have found the optimal dimensions, such as length, of the racetrack resonator. And then for improving the WDM filter characteristics of microring resonator, we have designed bent photonic crystal waveguide. Integrating microring resonator with bent photonic crystal waveguide can offer additional functions such as band pass filtering function.

Integrated micro-racetrack resonator arrays and photonic crystal bandpass filter arrays for WDM application

The new power-splitting scheme is proposed in 2-dimensional photonic crystals with a triangular array of air-holes. The power splitting is due to coupling between the localized modes of line-defect waveguides. By finite-difference time-domain computation, the power-splitter is analyzed. The computed frequency spectra show up to 47% transmittance per each output.

Kyung-Mi Moon

Papers

Photonic crystal power-splitter based on directional coupling.

Filtering Characteristics of Photonic Crystal Waveguide with Bends

Use of waveguide bending as a new approach in the design of a triangular-lattice photonic crystal bandpass filter

Integrated micro-racetrack resonator arrays and photonic crystal bandpass filter arrays for WDM application

Efficient photonic crystal power-splitter