Showing papers on "Silicon photonics published in 1992"

Theory of Dielectric Optical Waveguides. 2nd Edition

Abstract: (1992). Theory of Dielectric Optical Waveguides. 2nd Edition. Journal of Modern Optics: Vol. 39, No. 4, pp. 901-901.

Low-loss planar optical waveguides fabricated in SIMOX material

Abstract: Planar optical waveguides have been formed in SIMOX structures, and the effect of the thickness of the buried oxide layer on propagation loss hs been studied. Waveguides with a guiding layer thickness of approximately 6 mu m have been measured, and the lowest loss, which is on the order of that of pure silicon, was observed for a buried oxide thickness of 0.4 mu m, at a measurement wavelength of 1.523 mu m. >

Method to reduce the optical Kerr-effect-induced bias in an optical passive ring-resonator gyro

Abstract: The optical passive ring-resonator gyro (OPRG) utilizes a high-finesse fiber ring resonator. A novel method to reduce the optical Kerr-effect-induced bias is proposed. The bias is monitored by modulating the light-source intensity, and fed back into one lightwave intensity traveling in the resonator to make it zero. The experiment to verify the basic operation of this method is successfully carried out. >

Semiconductor diode optical switching arrays utilizing low-loss, passive waveguides

Abstract: Arrays of blocking optical switches formed from optically amplifying waveguides are used to transmit or block one or more input beams to one or more selected optical channels. Passive optical waveguides couple the optical input to the amplifying waveguides. Optical splitters monolithically formed with passive optical waveguides are used to route the optical signal from a single fiber to the array of amplifying waveguides.

Method of producing optical integrated circuit

Abstract: There is provided a method of producing efficiently custom IC optical integrated circuits with convenient connections between the optical devices with less loss of light and with different connections but similar configuration. The optical integrated circuit comprises a plurality of ridge-type active optical devices formed of a variable wavelength laser section (1), a light modulator (2) and a ridge-type passive Y-branching optical waveguide (4) for connecting the ridge-type active optical devices with each other or with output waveguides. The ridge sections of the ridge-type active optical device and the ridge-type passive optical waveguide are formed by the selective crystal growth.

Sensor application of SiON integrated optical waveguides on silicon

Abstract: Integrated optical waveguides are especially suitable for use as optical sensors, e.g., for measuring pressure, temperature or gases, due to their specific physical and technical properties. Silicon oxinitride (SiON) thin films are deposited by thermal oxidation and LPCVD, respectively, and structured by means of lithography and plasma etching. The refractive index of the silicon oxinitride waveguide layer, sandwiched between two silicon dioxide layers, is adjustable. The relation of the propagation properties to elongation and temperature has been studied to determine if integrated optical interferometer structures may be used as sensors. A desired specific interdependence of these properties can be achieved by a proper choice of the layered structure of the waveguide. An integrated optical Mach-Zehnder interferometer crossing a silicon membrane micromachined into the silicon substrate is presented as an example for pressure sensing. One arm is placed on the silicon membrane to which pressure is applied; the other arm is used as a reference. The optical pathlength is varied by elongation of the membrane, which has a direct effect on the index of the waveguide layers. The elongation of the membrane causes a change of the propagation properties in the interferometer arms, and thus a change in the interferogram. This resulting interferogram, which is a function of the elongation, may be detected, for example, by an integrated photodiode at the interferometer junction.

A novel integrated-twin-guide (ITG) optical switch with a built-in TIR region

Abstract: The authors propose a novel integrated-twin-guide (ITG) optical switch with a built-in TIR region to enlarge the spatial separation of output lights, which is suitable for a compact optical switching matrix array. A switching operation was observed in a GaInAsP/InP MQW ITG optical switch utilizing electric-field induced refractive index variation. >

Germanium-diffused waveguides in silicon for lambda =1.3 mu m and lambda =1.55 mu m with losses below 0.5 dB/cm

Abstract: The authors present a simple technique for the fabrication of integrated optical channel waveguides that are prepared by indiffusion of an E-beam evaporated amorphous alloy of germanium and silicon into commercially available silicon with low dopant concentration, using only simple technological processes such as standard lithography, PVD, and diffusion. The waveguides are polarization independent and have waveguide losses as low as 0.3 dB/cm at wavelengths of lambda =1.3 mu m and lambda =1.55 mu m. The spot sizes are well suited for low-loss single-mode fiber device coupling, being on the order of a few microns in both horizontal and vertical directions. >

Buried optical waveguide polarizer by titanium indiffusion and proton-exchange in LiNbO/sub 3/

Abstract: Buried optical waveguide polarizers on LiNbO/sub 3/ have been realized by titanium indiffusion, followed by proton-exchange and annealing. The proton-exchange process decreases the ordinary refractive index and so modifies the index profile of the titanium indiffused waveguide. The measured intensity profile is in good agreement with calculation. An aluminum film absorbs the surface TM mode on z-cut LiNbO/sub 3/, leaving a buried nearly symmetric TE mode with lower optical loss than surface-guided TE modes. The extinction ratio obtained is estimated to be greater than 50 dB/cm at 0.633 mu m. >

Results of Monolithic Integration of Optical Waveguides, Photodiodes and CMOS Circuits on Silicon

Abstract: Optical devices like waveguides, beam splitters and Mach-Zehnder interferometers are integrated on silicon substrate. To reduce the silicon area necessary for waveguide curvatures integrated mirrors are applied. The optical components are coupled to CMOS amplifiers and digital circuits via photodetectors in a monolithic integration technique on a single silicon chip. Measurement results of the optical structures, the coupling characteristics of waveguides to photodiodes and of complete system operation are given.

Optical functional device by vertical and direct integration of heterojunction phototransistor and laser diode

Abstract: An optical device with various functions is actualized by integrating vertically and directly heterojunction phototransistors and a laser diode and by adjusting the internal optical feedback. The optical amplification with a good linearity between input and output lights is realized by suppressing the internal optical feedback. The large gain of over 100 is achieved in the wide wavelength range from 0.75 to 1.25 mu m. The optical thresholding function is achieved by changing the load line in the case of the optical amplification. The optical switching function with large gain and high sensitivity is obtained by utilizing the internal optical feedback most effectively. The optical bistable function is obtained when the amount of the optical feedback becomes moderate. The optical feedback inside the device is theoretically investigated to explain these functions systematically. >

Semiconductor laser apparatus with curved waveguide

Abstract: A semiconductor laser apparatus having an optical waveguide made of a semiconductor crystal, an optical cavity made of a mirror facet for reflecting light into the optical waveguide, and an optical gain region occupying at least part of the optical waveguide for generating an optical gain when powered. The optical gain region exists over a linear portion of the optical waveguide. The remaining portion of the optical waveguide is at least partially bent in structure.

Optical waveguide theory by the finite element method

Abstract: 1. Finite Element Method. 2. Planar Optical Waveguides. 3. Optical Channel Waveguides. 4. Optical Fibres. 5. Polarization-Maintaining Optical Fibres. 6. Optical Gratings. 7. Optical Waveguide Discontinuities. 8. Nonlinear Optical Waveguide. 9. Optical Solitons. 10. Quantum Well Structures.

Limits of long-distance soliton transmission in optical fibers with laser diodes as pulse sources

Abstract: To employ soliton transmission in practical optical fiber communication systems, it is desired that semiconductor laser diodes (LDs) can be used as the optical soliton sources. The authors show that, when pulses generated by LDs are used for soliton transmission, the large frequency noise of LDs causes jitter in soliton arrival times, and makes a limit on the bit-rate distance product of the soliton transmission system. This limit is shown to be proportional to the square root of the output peak power of the pulses generated by LDs, and has a value of 12800 GHz-km for pulses with an output peak power of 10 mW and a duration of 20 ps. >

Optical amplification system

Abstract: An optical amplification system capable of operating without being affected by the waveform of the incoming optical signal is provided for amplifying the optical signal in its optical waveguide by the effect of stimulated emission of a fluorescent substance induced by pumped light. According to a first aspect of the invention, an optical amplification system turns on its pumping source 8 when there is an optical signal s1 in the optical waveguide 5 whereas the pumping source 8 is kept off as long as no optical signal s1 is found in the optical waveguide 5 so that, when the pumping source 8 is turned on, pumped light from the pumping source 8 is fed to the optical waveguide 5 with a delay of time relative to the incoming optical signal s1. According to a second aspect of the invention, the inside of the optical wave-guide 5 is constantly kept under an excited condition so that, when no optical signal s1 is found in the optical waveguide 5, dummy light s3 is fed to the optical wave-guide 5, whereas no dummy light s3 is fed to the optical waveguide 5 once an optical signal s1 is introduced to the optical waveguide 5. With such an arrangement, since no optical amplification takes place at the rising edge of an incoming optical signal and hence the operation of optical amplification is not dependent on the waveform of the incoming optical signal, a safe and stable optical amplification system can be established.

Optical waveguide analysis

Abstract: Types of Optical Waveguide and Optical Techniques. Basics of Wave Guide Analysis. Waveguiding Mode of Optical Waveguides. Analytical Approximation Solutions for Waveguides. Finite Element Analysis of Waveguides.

Silica-based Finesse-variable Ring Resonator

Abstract: A finesse-variable ring resonator with a free spectral range of 2.5 GHz is demonstrated using silica-based optical waveguides. The finesse is controlled with a coupling-ratio-variable coupler, which is composed of a symmetrical Mach-Zehnder interferometer and thermooptic phase shifters. The finesse of the resonator is changed continuously from 6 to 27. >

Photonic memory switch: monolithic integration of a voltage-controlled bistable laser diode and an optical gate

Abstract: An electrically controlled photonic memory switch which monolithically integrates a voltage-controlled bistable laser diode and an optical gate on an InP substrate is fabricated. Time-division optical signal processing such as pulsewidth conversion and a pulse delay control is successfully demonstrated. >

Experiments on Optoelectronic Bistability in Distributed AIAs/GaAs-Bragg Reflectors

Abstract: We present measurements of optoelectronic bistability in hybrid distributed AlAs/GaAs Bragg reflectors. A threshold optical input power of 40 ?uW is observed leading to an estimated switching energy of 0.1 fJ?m?2 Using voltage shift of 60 V and an optical input power of 100 nW. an electroptical modulation of 40 % is obtained.

Method to reduce the optical kerr-effect induced bias in an optical passive ring-resonator gyro

Abstract: A novel method to reduce the optical Kerr-effect induced bias in the resonator-type gyro is presented. The bias is monitored by modulating light-source intensity, and fed back into one lightwave-intensity traveling in resonator to make it zero.

Optical constants of thin silicon films near the silicon L(2,3) absorption edge.

Abstract: Using synchrotron radiation, we determined the optical constants of thin silicon films in the wavelength region near the silicon L2,3 absorption edge. The extinction coefficient was determined from the transmittance of a thin, unbacked silicon film. The refractive index was determined from the reflectance of a sample consisting of an evaporated silicon film on gold. The thickness of the evaporated silicon film was chosen so that an interference feature appeared in the wavelength region above the edge where the silicon is transmissive. The shape of the interference feature is sensitive to the optical constants of silicon near the edge.

Method to reduce the optical Kerr-effect induced bias in an optical passive ring-resonator gyro

Abstract: The optical passive ring-resonator gyro (OPRG) utilizes a high-finesse fiber ring resonator. A novel method to reduce the optical Kerr-effect-induced bias is proposed. The bias is monitored by modulating the light-source intensity, and fed back into one lightwave intensity traveling in the resonator to make it zero. The experiment to verify the basic operation of this method is successfully carried out. >

Detection of localised polarization mode coupling using the optical kerr effect

Abstract: The optical Kerr effect is used to determine the locations of discrete mode coupling points in a polarization maintaining fibre. Differentiation of the received signal is demonstrated to reduce confusion from interactions between coupling points.

Ge-diffused passive optical waveguide structures in silicon

Abstract: For the fabrication of complex integrated optical devices such as a coherent optical receiver the separate investigation of its components like directional couplers, S-bends and Y-branches is a necessity A promising material for its realization is silicon since it exhibits an optical absorption of below 01cm−1 in the infrared regime (λ > 12μm) provided that waveguides with equally low losses can be produced The goal is achieved by indiffusing Ge from a stripe containing an alloy of germanium and silicon as proposed in /1,2/ thus minimizing losses due to free carriers Silicon also offers the potential of being the most developed material for electronic applications making it suitable for an opto-electronic integration

Optical waveguide device with reduced DC drift

Abstract: This invention aims at providing an optical waveguide device capable of reducing the dc drift and stably operating for an extended period of time. The optical waveguide device comprises an optical waveguide path (2) formed inside a surface of an electro-optical substrate (1), a buffer layer (3) formed on the optical waveguide path, and a driving electrode (4,5) for impressing an electric field so as to change a refractive index of the optical waveguide path, wherein the buffer layer is made of a transparent dielectric or insulator of a mixture between silicon dioxide and an oxide of at least one element selected from the group consisting of the metal elements of the Groups III to VIII, Ib and IIb of the Periodic Table and semiconductor elements other than silicon, or a transparent dielectric or insulator of an oxide between silicon and at least one of the metal elements and semiconductor elements described above.

Highly efficient coupling between two planar waveguides with different refractive index profiles by using nonlinear cladding

Abstract: An efficient butt-joined coupling scheme between single-mode planar waveguides with different refractive index profiles is proposed. The configuration consists of a tapered waveguide with nonlinear cladding. Power dependent coupling efficiency of the configuration is analyzed by the beam propagation method. The numerical results show that this configuration has high-coupling efficiency and is less sensitive to the offset between coupled waveguides if the input power is properly selected. >

Optical soliton transmission

Abstract: This paper discusses the basic properties and advantages of optical solitons which are under investigation in many countries for the purpose of their application in realizing ultrahigh-speed communications. Especially, the recent developments in erbium optical amplifiers, which are epochal in optical soliton transmission, have made soliton communication actually realizable. Here, the techniques of the so-called dynamic soliton communication are considered and recent research is reported.