A nonlinear dielectric material is incorporated within a photonic crystal as a means of changing the refractive index of a defect In this way, the resonant frequency can be easily adjusted, after fabrication, by external mechanisms (either optical or electronic) The ability to tune the frequency of a resonant mode is useful for constructing photonic integrated devices, thus the invention enables the use of a photonic-crystal microcavity for such purposes In one embodiment there is provided a photonic crystal having a periodic dielectric structure, and a defect positioned within the structure to define a microcavity The defect includes a nonlinear material and being adapted to have an induced variation in index of refraction so as to tune the resonant mode of the microcavity

Tunable microcavity and method of using nonlinear materials in a photonic crystal

The invention relates to an optical device ( 50 ) for manipulating a light wave (λ) using a diffractive grating structure (G). According to the basic idea behind the invention a prior art type diffractive grating structure having a permanently shaped surface relief is substituted with an electrically deformable diffractive grating structure (G), where a preformed, basic surface relief of the grating is composed of dielectric and deformable viscoelastic material, which can be electrically and sequentially fine tuned in shape to adjust the diffraction properties of said grating individually for different wavelengths. The invention permits manufacture of virtual display devices with a significantly larger exit pupil diameter than prior art solutions without degrading the color uniformity of the display device.

Electrically tunable diffractive grating element

A communication network has a flexible bi-directional bus architecture (FBDNA) and is arranged as a ring structure. Each node of the network has at least one on/off node switch, i.e., a switch that permits or blocks transmission around what would otherwise be a ring. If the network has one node switch per node, one node switch is set initially off to avoid problems with circulating amplified spontaneous emission (ASE) normally associated with a ring structure. If a fiber break occurs, the node switch (or node switches) in the node (or nodes) next to the break and on the same side of the node as the break switches off, and the node switch that was off before the break switches on, permitting the network to operate largely as before. If the network has two node switches per node, two node switches next to each other in neighboring nodes are initially set off, and if a cable break occurs, both node switches around a break switch off, and the node switches that were initially off switch on. The network provides protective switching of traffic and solves the problem of circulating ASE in a simple and economical way. The network also permits wavelength reconfiguration to reduce the number of required wavelengths.

Optical multichannel system

An arrayed wavelength grating device has a series of waveguiding channels (3) interconnecting two free space regions (2, 4) across which light inputting and outputting the device passes. There are differences in optical path length between any two of said channels (3) lying adjacent to one other in said series, which differences are defined by respective optical path length increments. The optical path length progression across said channels (3) is non-linear, not being defined by any one value of the path length increments, nor by a plural number of values of the path length increments each defining a linear optical path length progression of a subset of at least three of said channels (3).

Wavelength division multiplexing

A fast interferometric tunable optical filter consists of a variable delay line, with a fast phase modulator (10) inserted into the line, which acts as a resonator loop (8, 43) and is connected between the ports of an optical coupler (6, 14). The filter provides tuning speeds of the order of one nanosecond, making the filter suitable for use in selecting a desired wavelength division multiplexed signal as used in optical communications systems. The filter can be implemented in single resonator form, or, to provide improved performance, in a compound resonator form. It can also be constructed in fiber optical form (24, 25), or in a monolithic form on a chip of gallium arsenide in an integrated optics configuration, thereby providing lower production costs and improved performance.

Ultra-fast tunable optical filters

A tunable optical filter for use in wavelength division multiplexing systems. The optical filter contains a plurality of tunable reflection gratings which block all of the channels in the incoming lightwave. An electrode or a heating element is provided for each reflection grating to tune the reflection gratings so that their reflection bands do not coincide with a desired channel or channels thereby allowing the desired channel or channels to pass through the filter.

Tunable optical filter

A modified DBR laser having at least one extended tuning range is disclosed. A plurality of gratings are arranged on opposing sides of a gain section which can be selectively tuned to provide one or more continuous wavelength ranges of laser light.

Alternating grating tunable DBR laser

An interferometric tunable optical filter selects a predetermined wavelength or wavelengths from a wavelength division multiplexed signal. The optical filter splits an input signal into a plurality of waveguide branches. In each branch, the amplitude and phase of the signal can be individually controlled. The signals are then recombined. The resulting interference gives a wavelength dependent transmission spectrum that can be adjusted as desired.

Interferometric tunable optical filter

The present invention relates to an arrangement (10) and a method respectively for wavelength dependent routing of optical signals including a number of wavelengths. The arrangement comprises an optical Add-Drop multiplexing arrangement with input and output waveguides which comprises a routing device (5) with in- and outputs. The routing device (5) includes splitting means (11) with a number of inputs and combining means (12) with a number of outputs. One of said inputs (13N) and outputs (14N) respectively are used for a multi wavelength input whereas another input (13N-1) and another output (14N-1) respectively are used for an add/drop wavelength respectively whereas the other inputs and outputs (131-13N-2; 141-14N-2) are used for looping back of the remaining wavelengths. Between the splitting and combining means a number of branch waveguides are arranged and both wavelength demultiplexing/multiplexing and switching is provided for by the routing device (5).

Arrangement and method relating to optical transmission

In a tunable laser device a plurality of basically identical lasers (3, 3') are arranged adjacent to each other in a line or row on a common substrate (1). The lasers (3, 3') can be DFB-type and they have different emission wavelengths, obtained from e.g. different pitches of gratings (5) which define the wavelengths of the respective lasers. The lasers can be activated to emit light independently of each other by supplying electrical current to contacts (11) located on the top sides of the lasers. When a laser is activated, the other lasers are biased, so that lasers located at one side of the active laser will be transparent to the emitted light, which can then travel from the lasers through an electrooptic modulator (17), and the lasers located at the other side will absorb the light. By controlling the temperature, the wavelength of emitted light can be finely adjusted. Such a laser device has a compact structure, is fairly insensitive to variations of the used drive currents and can in a simple way be adjusted to different operating conditions and be compensated for aging effects.

Jean-Pierre Weber

Papers

Tunable optical filter

Alternating grating tunable DBR laser

Interferometric tunable optical filter

Arrangement and method relating to optical transmission

Producing laser light of different wavelengths