1 X N dynamic optical coupler based on Dammann gratings

We present two novel 1XN dynamic optical couplers that are based on Dammann gratings to achieve dynamic optical coupled technology. One is presented by employing a specially designed Dammann grating that consists of the Dammann-grating area and the blank area. The other is developed by using two complementary even-numbered Dammann gratings. The couplers can achieve the function conversion between a beam splitter and a combiner according to the modulation of the gratings. We have experimentally demonstrated 1X8 dynamic optical couplers at the wavelength of 1550 nm. The experimental results and the analyses are reported in detail.

High efficiency fiber to waveguide optical coupler in silicon-on-insulator-based slot waveguides - art. no. 68310R

We propose a novel optical fiber-to-waveguide coupler for integrated optical circuits. The proper materials and structural parameters of the coupler, which is based on a slot waveguide, are carefully analyzed using a full-vectorial three dimensional mode solver. Because the effective refractive index of the mode in a silicon-on-insulator-based slot waveguide can be extremely close to that of the fiber, a highly efficient fiber-to-waveguide coupling application can be realized. For a TE-like mode, the calculated minimum mismatch loss is about 1.8dB at 1550nm, and the mode conversion loss can be less than 0.5dB. The discussion of the present state-of-the-art is also involved. The proposed coupler can be used in chip-to-chip communication.

Paired interference 3-dB coupler based on SOI rib waveguides with anisotropic chemical wet etching

A 3-dB paired interference (PI) optical coupler in silicon-on-insulator (SOI) based on rib waveguides with trapezoidal cross section was designed with simulation by a modified finite-difference beam propagation method (FD-BPM) and fabricated by potassium hydroxide (KOH) anisotropic chemical wet etching. Theoretically, tolerances of width, length, and port distance are more than 1, 100, and 1 mu m, respectively. Smooth interface was obtained with the propagation loss of 1.1 dB/cm at the wavelength of 1.55 mu m. The coupler has a good uniformity of 0.2 dB and low excess loss of less than 2 dB.

Multimode interference 3-dB coupler in silicon-on-insulator based on silicon rib waveguides with trapezoidal cross section

A 3-dB multimode interference optical coupler based on rib waveguides with trapezoidal cross section was designed and fabricated on silicon-on-insulator wafer. Potassium hydroxide (KOH) anisotropic chemical etching of silicon was used to fabricate the waveguides to obtain smooth interface. A modified finite-difference beam propagation method was used to simulate the multimode rib waveguide with slope interfaces. The rms roughness of etching interface is as small as 1.49 nm. The propagation loss of the waveguide is 1.3 dB/cm at wavelength of 1.55 mum. The fabricated 3-dB coupler has a good uniformity of 0.2 dB.

MMI optical couplers and switches with SOI technology

MMI (multimode interference) coupler, modulator and switch based on SOI (silicon- on-insulator) have been become more and more attractive in optical systems since they show important performances. SiO2 thin cladding layers (<1.0mum) can be used in SOI waveguide due to the large index step between Si and SiO2, making them compatible with the VLSI technology. The design and fabrication of multimode interference (MMI) optical coupler, modulator and switche in SOI technology are presented in the paper. The results demonstrated that the modulator has an extinction ratio of -11.0dB and excess loss of -2.5dB, while the optical switch has a crosstalk of -12.5dB and responding time of less than 20 mus.

Integrated MMI optical couplers and optical switches in Silicon-on-insulator technology

Integrated multimode interference coupler based on silicon-on-insulator has been become a kind of more and more attractive device in optical systems. Thin cladding layers (<1.0mum) can be used in SOI waveguide due to the large index step between Si and SiO2, making them compatible with the VLSI technology. Here we demonstrate the design and fabrication of multimode interference (MMI) optical couplers and optical switches in SOI technology.

Simulation and analysis of a collisionless optical interconnection network

This article describes the simulation and analysis of collisionless optical interconnection network, which the objective is to achieve a high performance level based on a single protocol control. The optical coupler has one shared control channel and N communication channels. Each network node two communication modules one for packet transmission/reception and another for control channel access. We show by simulation that system achieves a high performance and ensures high scalability.

基于达曼光栅的动态光耦合器

提出了一种基于达曼光栅的动态光耦合器,通过控制装置中达曼光栅位移参量,可实现入射光束的分束或合束以及两者之间的动态转换。适当选择达曼光栅类型可实现任意N×M的动态光耦合。实验中以1550 nm光波长为例,对1×8达曼动态光耦合器进行测量,测得其实现光开关功能时插入损耗为0.43 dB,实现光分束功能时均匀性达到0.03,单路插入损耗均值为10.5 dB。该实验装置易于调节、体积小、能耗低,且关键元件达曼光栅制作工艺成熟,易于批量化生产。特别是在实现中大规模光交换阵列时,该方案就具有更明显的优越性,有实用意

FREQUENCY RESPONSE OF FIBER RING RESONATOR AND ITS APPLICATION IN DFB LASER WAVELENGTH VARIATION MEASUREMENT

Frequency response of a fiber ring resonator (FRR) composed of an ordinary optical coupler and a segment of optical fiber is theoretically and experimentally investigated. The frequency response equation based oil small-signal modulation is derived and studied in detail. It is shown that the shape of the frequency response curve is very sensitive to the wavelength; as a result, the FRR can be applied to measure the wavelength of a lightwave source with high resolution. With this method, we demonstrate the measurement of tiny changes of wavelength of a DFB laser. (C) 2009 Wiley Periodicals. Inc. Microwave Opt Technol Lett 51 2444-2448, 2009 Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24608

Signal bandwidth of general N x N multimode interference couplers

Analytical expression of signal bandwidth of general straight and tapered N x N multimode interference (MMI) couplers is presented. The signal bandwidth is characterized as a function of mode relative energy, mode propagation delay time, and mode pulse broadening in the multimode section of MMI coupler. The model is used to evaluate the signal bandwidth of specific couplers. Results indicate that the signal bandwidth decreases seriously with the increase of channel number and channel guide space. Compared with the straight MMI coupler, the tapered MMI coupler has an improved signal bandwidth.

Designing a coupler for the intersatellite optical communication system

Coupling a single-mode laser diode with 200 mW to a single-mode fiber (SMF) through an orthonormal aspherical cylindrical lens and a GRIN lens for the intersatellite optical communication system is proposed and demonstrated. We experimentally studied how the coupling efficiency changes with the SMF's position displacement and axial angle variation, and obtained 80 mW output power at the end of the SMF, which shows that the coupling units have satisfied the designed request. (c) 2007 Elsevier GmbH. All rights reserved.

All-optical switching in a vertical coupler space switch employing photocarrier-induced nonlinearity

A novel compact integrated nonlinear optical switch is demonstrated. Using a high-power picosecond pulse of 5-ps pulsewidth and 250-MHz repetition rate, all-optical switching with a contrast ratio of 23 dB has been achieved using an in-fiber input power < 14 dBm (100 pJ/pulse). The switch speed depends on the carrier sweep-out time, which can be reduced to the 10 ps range by either applying a reverse bias or by introduction of carrier recombination centers in the active layer.

Optical microwave generation using two parallel DFB lasers integrated with Y-branch waveguide coupler

A new device of two parallel distributed feedback (DFB) lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in the Y-branch waveguide coupler through frequency beating of the two laser modes coming from two DFB laser in parallel, which had a small difference in frequency. Continuous rapid tuning of optical microwave signal from 13 to 42 GHz were realized by adjusting independently the driving currents injected into the two DFB lasers.

Directional-coupler-based Mach-Zehnder interferometer in silicon-on-insulator technology for optical intensity modulation

Based on silicon-on-insulator (SOI) technology, a Mach-Zehnder interferometer (MZI) is fabricated, in which two directional couplers serve as power splitter and combiner. The free carrier plasma dispersion effect of Si is adopted to achieve the phase modulation and the consequent intensity modulation of optical fields. The device presents an insertion loss of 2.61 dB and an extinction ratio of 19.6 dB. The rise time and fall time are 676 ns and 552 ns, respectively. Detailed analysis and explanation of the performance behaviors are also presented. (c) 2007 Society of Photo-Optical Instrumentation Engineers.