Abstract:
The present invention provides a current blocking structure for electronic devices, preferably optoelectronic devices. The current blocking structure comprises a semiconductor material arrangement comprising an n-type ruthenium doped indium phosphide (Ru-InP) layer and a first p-type semiconductor material layer wherein the n-type Ru-InP layer is less than 0.6µm thick. The semiconductor material arrangement and p-type semiconductor material layer form a current blocking p-n junction. The current blocking structure may further comprise other n-type layers and/or multiple n-type Ru-InP layers and/or intrinsic/undoped layers wherein the n-type Ru-InP layers may be thicker than 0.6µm.
Abstract:
An optical arrangement comprises a semiconductor optical amplifier; a collimator; and an optical retro-reflector; said collimator being located between said amplifier and said optical retro-reflector; wherein said retro-reflector is formed as a wedge-shaped block of optically transparent medium with a front facet and a rear facet; said front facet comprising a thin film filter; and said rear facet comprising a wide band reflector.
Abstract:
A system for generating and detecting terahertz radiation comprises a first laser (1) and a second laser (2), each having a different frequency of laser light output. The system further comprises a radiation generating stage (4, 9) arranged to generate terahertz radiation by beating the light output of the first laser (1) with the light output of the second laser (2). A radiation detecting stage (12) is arranged to modulate light output from the first laser (1) with received terahertz radiation.
Abstract:
A detector for electromagnetic radiation in the range 80 GHz to 4 THz comprises a laser light source (115) an optical modulator (13) arranged to modulate light from the laser light source (11) and a filter system (17) for selecting a defined range of frequencies of the modulated light. The optical modulator is an electroabsorption modulator (13) with an antenna (15) which is sensitive to electromagnetic radiation in the range 80 GHz to 4 THz. The signal received by the antenna (15) modulates the electric field across the electroabsorption modulator (13), whereby to modulate the light from the laser light source (11).
Abstract:
A method for generating an optical single sideband signal comprising the steps of splitting an optical field into two parts and introducing a relative phase delay of +/- π/4 radians in each direction of transmission to one of the parts, intensity reflection-modulating each part with electrical signals having a relative phase delay of +/- π/2 radians and then recombining the reflection-modulated signals.
Abstract translation:一种用于产生光学单边带信号的方法,包括以下步骤:将光场分成两部分,并将每个传输方向上的+/- p / 4弧度的相对相位延迟引入到所述部分之一,对每个部分进行强度反射调制 电信号具有+/- p / 2弧度的相对相位延迟,然后重组反射调制信号。
Abstract:
A method of fabricating a photonic device comprises the steps of providing a core pattern of waveguide core material (1) on a base layer (3) and applying a cladding layer (2) over the core material 1 and the base layer (3). The height of the surface of the cladding layer (2) over the base layer (3) varies in dependence on the pattern of core material (1). The core pattern is designed with at least two reference regions, each having a width w that is selected to provide a peak of the cladding layer (2) with a predetermined height h1 over each reference region. The core pattern is further designed such that a line between the peaks of the reference regions is higher than any intervening peaks of the cladding layer, whereby the peaks of the reference regions provide a vertical alignment reference.
Abstract:
An optical duobinary modulated signal generator comprises: • a splitter for splitting an optical field into a first part and a second part; • means for inducing a phase delay in the transmission of said first part relative said second part; and · a modulator for intensity modulating said first part and said second part, which in use, provides an optical phase shift between said first part and said second part.
Abstract:
A hybrid integrated tuneable optical laser device, suitable for tuning to different wavelengths via a piezo micromotor (6) controlled optical filter (4) in an external cavity. Once the laser is fixed at a selected wavelength, no power is required to be applied to the wavelength tuning element to maintain the wavelength stability.
Abstract:
An electroabsorption modulator comprises an absorption layer (7) between at least one layer of p-doped semiconductor (6) and at least one layer of n-doped semiconductor (8). The layers form a ridge waveguide structure. The thickness of the absorption layer is between 9 and 60 nm and the width of the ridge is between 4.5 and 12 microns.
Abstract:
A multiwavelength transmitter comprises several laser sources (1) each configured to generate light of a different wavelength and a first array waveguide grating (2) arranged to direct light from each of the laser sources (1) into a first waveguide. The transmitter further comprises several electroabsorption modulators (7) each arranged to modulate light at one of the wavelengths with a respective data signal and a second array waveguide grating (6) arranged to direct each of said different wavelengths of light from the first waveguide to a respective one of the modulators (7). The optical modulators (7) are reflective optical modulators and the second array waveguide grating (6) is arranged to direct the modulated light reflected from each of the optical modulators (7) back into the first waveguide. An optical circulator (5) is provided in the first waveguide to couple modulated light from the second array waveguide grating (6) into an output waveguide. The laser sources each comprise a respective reflective semiconductor optical amplifier (1) and share a common cavity reflector (3). The first array waveguide grating (2) is located in the optical path between the semiconductor optical amplifiers (1) and the common cavity reflector (3). The transmitter has the advantage that it can be manufactured by hybrid integration of a monolithic wavelength generation sub-module and a monolithic data modulation sub-module.