Abstract: There is herein described light generating electronic components with improved light extraction and a method of manufacturing said electronic components. More particularly, there is described LEDs having improved light extraction and a method of manufacturing said LEDs.

Abstract: There is herein described light generating electronic components with improved light extraction and a method of manufacturing said electronic components. More particularly, there is described LEDs having improved light extraction and a method of manufacturing said LEDs.

Abstract: There is herein described light generating electronic components with improved light extraction and a method of manufacturing said electronic components. More particularly, there is described LEDs having improved light extraction and a method of manufacturing said LEDs.

Abstract: There is herein described light generating electronic components with improved light extraction and a method of manufacturing said electronic components. More particularly, there is described LEDs having improved light extraction and a method of manufacturing said LEDs.

Abstract: There is herein described light generating electronic components with improved light extraction and a method of manufacturing said electronic components. More particularly, there is described LEDs having improved light extraction and a method of manufacturing said LEDs.

Abstract: There is herein described light generating electronic components with improved light extraction and a method of manufacturing said electronic components. More particularly, there is described LEDs having improved light extraction and a method of manufacturing said LEDs.

Abstract: A MEMS device comprising a flexible membrane that is free to move in response to pressure differences generated by sound waves. A first electrode mechanically coupled to the flexible membrane, and together form a first capacitive plate. A second electrode mechanically coupled to a generally rigid structural layer or back-plate, which together form a second capacitive plate. A back-volume is provided below the membrane. A first cavity located directly below the membrane. Interposed between the first and second electrodes is a second cavity. A plurality of bleed holes connected the first cavity and the second cavity. Acoustic holes are arranged in the back-plate so as to allow free movement of air molecules, such that the sound waves can enter the second cavity. The first and second cavities in association with the back-volume allow the membrane to move in response to the sound waves entering via the acoustic holes in the back-plate.

Abstract: A MEMS device comprising a flexible membrane that is free to move in response to pressure differences generated by sound waves. A first electrode mechanically coupled to the flexible membrane, and together form a first capacitive plate. A second electrode mechanically coupled to a generally rigid structural layer or back-plate, which together form a second capacitive plate. A back-volume is provided below the membrane. A first cavity located directly below the membrane. Interposed between the first and second electrodes is a second cavity. A plurality of bleed holes connect the first cavity and the second cavity. Acoustic holes are arranged in the back-plate so as to allow free movement of air molecules, such that the sound waves can enter the second cavity. The first and second cavities in association with the back-volume allow the membrane to move in response to the sound waves entering via the acoustic holes in the back-plate.

Abstract: A MEMS device, for example a capacitive microphone, comprises a flexible membrane 11 that is free to move in response to pressure differences generated by sound waves. A first electrode 13 is mechanically coupled to the flexible membrane 11, and together form a first capacitive plate of the capacitive microphone device. A second electrode 23 is mechanically coupled to a generally rigid structural layer or back-plate 14, which together form a second capacitive plate of the capacitive microphone device. The capacitive microphone is formed on a substrate 1, for example a silicon wafer. A back-volume 33 is provided below the membrane 11, and is formed using a “back-etch” through the substrate 1. A first cavity 9 is located directly below the membrane 11, and is formed using a first sacrificial layer during the fabrication process. Interposed between the first and second electrodes 13 and 23 is a second cavity 17, which is formed using a second sacrificial layer during the fabrication process.

Abstract: Passive, self-adjusting and tracking optical wavelength filters are described. The filters are absorptive and can be of either transmissive or reflective type. The filters comprise an unpumped doped optical waveguide configured so that signals of different wavelength are spatially decoupled to some extent. The self-adjustment of the filter centre wavelength is achieved by the combined effects of the power-dependent saturable absorption, provided by an appropriate dopant, and partial longitudinal hole burning provided by the spatial decoupling of the different wavelengths. External cavity lasers using this type of filter in the external cavity are also described. This external cavity configuration can provide stable single frequency operation of, for example, a semiconductor laser. By using a saturable absorber for the external cavity (e.g. an erbium doped fibre), longitudinal mode-hopping can be suppressed, ensuring single frequency operation.

Abstract: In an optical amplifier, comprising a rare earth doped optical waveguide, in which signals at signal wavelength and pump power at pump wavelength are coupled together, a differential loss inducing means is located in a predetermined position along the length of the waveguide, causing a loss for the signal greater by a predetermined loss amount than the loss for the pump wavelength, said predetermined loss amount and said predetermined loss position being chosen in a mutual relationship to cause an amplification of lower power input signals, in said signal input power range, greater than the amplification of higher power input signals in said range, by an amount causing a substantially constant output power in a dynamic range of input signals greater than 15 dB.

Abstract: An optical amplifier for amplifying signals of different wavelengths throughout a spectral window modifies the amplification of each signal such that the output levels of the signals are more equal than the input levels thereof when the input levels differ by more than a predetermined amount. In one embodiment this is achieved by providing a dichroic reflector at one end of an amplifying fibre so that standing wave patterns are set up in the amplifying fibre by interference of the forward and reflected signal lights, at the different wavelengths, the signal at each wavelength preferentially decreasing its own gain with increasing signal level.

Abstract: An optical amplifier comprises first (22) and second (24) lengths of erbium-doped fibre connected in series via an isolator 20 which reduces the transmission of backward-travelling ASE from the second length to the first length when pump power in inputted in to the first length.

Abstract: An Ar.sup.+ ion laser pumped optical fibre amplifier is provided with an optical fibre having a core which has been solution doped using a solution of an aluminum and an erbium salt.

Abstract: The spectral-gain characteristics of an erbium-doped fibre amplifier have been tailored by incorporating a gain-shaping-filter within the amplifier. The filter is chosen to modify the natural gain spectrum of the amplifier so as to suppress the gain peak and thus flatten the overall spectral-gain profile. Because the amplifier is distributed, it is possible to insert one or more filters along the length of the fibre. It is shown that there are considerable advantages to locating the filter within the length of the amplifier, rather than at the end, which is the more obvious choice. Advantages are that the amplifier pump efficiency is almost unaffected and the output saturation power is similar to that of the unshaped amplifier. In addition, the flat spectral gain provides an amplifier ideally-suited for use at a number of signal wavelengths, as required for wavelength-division multiplexing (WDM).