Wavelength Demultiplexing Devices Research Articles

16-Channel Wavelength Division Multiplexers Based on Subwavelength Grating

Wavelength Division Multiplexing (WDM) plays an important role in optical interconnection. In this paper, a 16-channel WDM device is designed on a Silicon-On-Insulator (SOI) substrate by using a sub-wavelength grating (SWG) structure, which can cover O-band and C-band at the same time, and the output channel is reversely coupled from the main waveguide to realize wavelength demultiplexing. The simulation results show that the loss of our 16-channel wavelength demultiplexing device is less than 0.5 dB and the crosstalk is less than 17 dB. When WDM is performed in O-band, the transmission loss of the C-band in the bus waveguide is less than 0.05 dB and is insensitive to the grating duty cycle, with good process tolerance. The footprint of the device is 200 μm × 150 μm, and the size of the single-channel filter is 200 μm × 2 μm, which can realize WDM with large bandwidth in a compact structure.

Polarization-tunable compact plasmonic wavelength demultiplexers based on Fano nanoantennas

A compact plasmonic wavelength demultiplexer is an essential prerequisite for practical applications, including the next-generation on-chip devices, near-field optical trapping, and micromanipulation. However, alleviating the polarization dependence of the wavelength demultiplexers remains one of the most challenging issues in realizing such a plasmonic device. Here we propose a gold disk-slit-based compact Fano-type nanoantenna capable of launching surface plasmon polaritons (SPPs) directionally when irradiated under different wavelengths of light, realizing a wavelength demultiplexing function. More importantly, our simulation results show that the shortage of requirement of specific light polarization direction excitation in such wavelength demultiplexers can be circumvented. Furthermore, it is found that the output channel of the SPP can be switched in multiple directions under different polarization excitations. In addition, the results show that the applicable wave band of the wavelength demultiplexing device can be flexibly adjusted by changing the size of the nanoantenna. The technique of introducing the polarization-tunable function into the wavelength demultiplexers in the plasmonic interconnect application enhances the freedom of information transmission and offers a promising building block for future high-speed and high-bandwidth on-chip optical communication.

A Four Green TM/Red TE Demultiplexer Based on Multi Slot-Waveguide Structures.

A four green transverse magnetic (TM)/red transverse electric (TE) light wavelength demultiplexer device, based on multi slot-waveguide (SW) structures is demonstrated. The device aims to demultiplex wavelengths in the green/red light range with wavelengths of 530, 540, 550, and 560 nm; 630, 640, 650, and 660 nm. This means that the device functions as a 1 × 4 demultiplexer for each polarization mode (TE/TM). The controlling of the light switching between two closer segment SWs under the TM/TE polarization mode was studied by designing a suitable SW structure and setting the right segment length to fit the coupling lengths of the operating wavelengths. The device is composed of six-segment SW units and six S-bends (SB) SW. The key SW and SB parameters were optimized and determined by a full vectorial beam propagation method (FV-BPM). Results show power losses better than 0.138 dB, crosstalk better than −21.14 dB, and an optical spectrum smaller than 9.39 nm, with an overall compact size of 104.5 µm. The device can be integrated in wavelength division multiplexing (WDM) for increasing data bit rate in a visible light communication (VLC) system.

Spin‐Selective and Wavelength‐Selective Demultiplexing Based on Waveguide‐Integrated All‐Dielectric Metasurfaces

AbstractA novel approach for the design of a spin‐selective directional coupler and spin‐selective wavelength demultiplexing device by integrating an all‐dielectric metasurface into a silicon nitride waveguide is proposed and demonstrated. Taking advantage of the intrinsic chirality of the electromagnetic field inside the waveguide, the propagation direction of the excited waveguide mode can be easily controlled by the spin and wavelength of the incident light. The coupling efficiency of the spin‐selective directional coupler toward one side can reach ≈51.6% at 1836 nm. In addition, the working wavelengths, coupling efficiency, peak width, and mode type can be easily tailored by adjusting the geometric parameters of the waveguide and the antenna arrays. This study may provide a further step in the development of photonic integrated circuits, integrated quantum optics, chiral optics, and high‐bit‐rate telecommunication applications.

A wavelength demultiplexing structure based on graphene nanoribbon resonators

A wavelength demultiplexing (WDM) structure based on graphene nanoribbon resonators is proposed and numerically investigated by the finite-difference time-domain (FDTD) method. The demultiplexing wavelength can be easily derived by adjusting the length of the resonator, which is accurately explained by the Fabry–Perot (F–P) resonant theory. Meanwhile, the transmission characteristics of the WDM structure are influenced by the coupling distance between the resonator and drop/bus waveguides, and the performance of the WDM device is analyzed at different nanoribbon width and chemical potential. In addition, in order to improve the transmission efficiency from the drop waveguide, a reflection structure is introduced at the end of the bus waveguide. The exact mechanism for the WDM structure is analyzed in detail using the temporal coupled-mode theory. The proposed structure will have potential applications in the field of ultra-compact WDM systems in highly integrated optical circuits.

Wavelength demultiplexing structure based on arrayed plasmonic slot cavities

A compact wavelength demultiplexing structure based on arrayed metal-insulator-metal (MIM) slot cavities is proposed and demonstrated numerically. The structure consists of a bus waveguide perpendicularly coupled with a series of slot cavities, each of which captures SPPs at the resonance frequency from the bus waveguide and tunes the transmission wavelength by changing its geometrical parameters. A cavity theory model is used to design the operating wavelengths of the structure. Moreover, single band transmission of each channel and the adjustable transmission bandwidth can be obtained by altering the drop waveguide positions and the coupling distance. The proposed arrayed slot cavity-based structure could be utilized to develop ultracompact optical wavelength demultiplexing device for large-scale photonic integration.

Phononic crystals and manipulation of sound

AbstractThe acoustic properties of phononic crystals are presented, using numerical simulations. In a first part we study some possible applications of these composite materials. In particular, we show that defect modes (cavities, wave guides, stubs...) inserted inside the 2D periodic structure may lead to the possibility of manipulating the propagation of sound and realizing selective frequency filters and efficient devices for wavelength demultiplexing. We also report on the vibration modes of a 2D plate, i.e. a phononic crystal of finite thickness along the axis of the inclusions. We investigate the existence of absolute band gaps in the band structure of the plate, either free or deposited on a substrate. This should open new perspectives in the field of high‐frequency radiofrequency devices. Finally, we present the possibility of devicing sonic insulators for frequencies of the order of kHz with relatively small thicknesses of the phononic crystal sample as compared to the wavelength. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Wavelength demultiplexers based on multimode interference effect in photonic crystals

We present a compact photonic crystal wavelength demultiplexing device based on multimode interference effect. The finite-difference time-domain method is used to verify and analyze the characteristics of the device. Results show the demultiplexing function of the device can be obtained with greater than 20 dB isolation ratio and about 20 nm bandwidth at both wavelength bands.

Fabrication of Near-Infrared Volume Phase Holographic Grism with High Efficiency and High Dispersion, and Its Application to a Wavelength De-multiplexing Device

We designed and developed a volume phase holographic (VPH) grism with high resolution and high efficiency in the near-infrared light domain (1550 nm) to be applied as a wavelength de-multiplexing device of a photonic network. In order to achieve both diffraction efficiency of over 80% and wavelength resolution of 0.08 nm, we newly designed and fabricated a VPH grism with high efficiency and high wavelength resolution in near-infrared wavelength region by sandwiching a VPH grating between prisms. An active feedback control technique was introduced to a two-beam interference exposure system, and we also applied it to a wavelength de-multiplexing device for a photonic network. Consequently, a VPH grism was successfully fabricated with diffraction efficiency of over 80% by employing the Bragg condition of 1550 nm at the incident wavelength from 1530 to 1570 nm, and high refractive index modulation of 0.047 was confirmed.

Compact demultiplexers and spectrometers for integrated photonics

Wavelength demultiplexing devices (WDD) disperse an input beam into a plurality of sub-beams, and are commonly used to separate optical channels at different wavelengths. Compact WDDs are of great interest for several integrated photonic applications including optical information processing, optical communications and networking, as well as integrated optical sensing such as ‘lab-on-a-chip’ biosensing systems. The compactness of these devices and their compatibility with integrated photonic and electronic platforms are among their main advantages when compared to other wavelength demultiplexing solutions. These advantages are the result of the wide range of controllable dispersive properties in a very compact structure enabled by the use of photonic crystals (PCs). Such dispersive properties are not available in conventional devices that usually rely on bulk or grating-based materials. For efficient WDD implementation, we use PCs. These structures, which consist of sub-wavelength periodic features, can be used to control the optical properties of materials: they have unique dispersive properties that are not present in naturally occurring optical materials. In particular, properly designed PCs can angularly separate optical beams of different wavelengths in widely different directions. By analogy with conventional prisms, this phenomenon is called the superprism effect and represents the primary physical effect used for the separation of wavelength channels of an optical signal as shown in Figure 1(a). Ideally, the compact spatial separation of different wavelengths would require a large angular difference between the directions of propagation of the different wavelengths. This would translate into a strong superprism effect for the selected PC. However, rapid variation of the angle withwavelength naturally Figure 1. Schematic representation of the three dispersive properties of photonic crystals used for wavelength demultiplexing: (a) the superprism effect, (b) negative diffraction, and (c) negative refraction.

Compact wavelength demultiplexing using focusing negative index photonic crystal superprisms

Here, we demonstrate a compact photonic crystal wavelength demultiplexing device based on a diffraction compensation scheme with two orders of magnitude performance improvement over the conventional superprism structures reported to date. We show that the main problems of the conventional superprism-based wavelength demultiplexing devices can be overcome by combining the superprism effect with two other main properties of photonic crystals, i.e., negative diffraction and negative refraction. Here, a 4-channel optical demultiplexer with a channel spacing of 8 nm and cross-talk level of better than -6.5 dB is experimentally demonstrated using a 4500 microm(2) photonic crystal region.

Wavelength demultiplexer using a multi-reflection-mirror waveguide

A new design scheme of a wavelength demultiplexer device structure using waveguide mirrors to generate a series of reflected light beams with wavelength dependent phases is proposed. The light propagated in the waveguide is reflected into a planar waveguide at multiple, partially reflecting mirrors, in which positions and a geometry of the waveguide are optimized to lower the filter response difference between the output ports. Methods to reduce the sidelobe level in the filter response are demonstrated.