摘要:
A semiconductor optical amplifier (SOA) has an overall gain that is substantially polarization independent, i.e., less than 1 dB difference between transverse electric (TE) and transverse magnetic (TM) gain. The SOA includes a residual cladding layer having different thicknesses over different portions of the gain section. Over a first portion of the gain section, the residual cladding layer is thinner than over a second portion of the gain section. This results in the first portion providing more gain to optical energy having a TE polarization state than optical energy having a TM polarization state. In the second portion of the gain section, however, more gain is provided to optical energy having a TM polarization state than energy having a TE polarization state. The resulting gain differences can be designed to offset one another so that the output has a gain that is substantially polarization independent.
摘要:
A method of selectively oxidizing III-V semiconductor material is provided. There is provided a III-V semiconductor system comprising a short-period super lattice (SSL) of N periods of alternating layers of an aluminum-bearing III-V compound semiconductor material and a second III-V semiconductor material where N≧2, at least one phosphorous-rich III-V semiconductor layer, and at least one substantially phosphorous-free III-V semiconductor layer between each of the at least one phosphorous-rich layers and the SSL. The III-V semiconductor system is exposed to oxidizing atmosphere to selectively oxidize at least a portion of the SSL.
摘要:
The invention describes a real-time in situ ellipsometric monitoring and control system using an ellipsometer to control the averaged refractive index of the deposited film during the AR coating of semiconductor laser diode facets for laser amplifiers and superluminescent LED. The input and output window birefringences are taken into account and calibrated the windows mounted on the vacuum chamber to include the effects of the pressure and mounting stress. In addition to the conventional four-medium model which gives an averaged refractive index, an adaptive multilayer model which takes into account an increasing number of layers as the evaporation proceeded is developed to monitor the instantaneous changes of the refractive index. Each ellipsometric measurement lasts only 0.5s and provides two sets of refractive index and thickness data as derived by the two multilayer models. Both measured data are used for the refractive index control to achieve a good feedback response. This fast and sensitive measurement technique makes possible the feedback control of the refractive index in real time which in turn allows for better control of the deposition condition and also improves the reproducibility of the AR coating process. By combining the two measured refractive indices and using the weighted average as the control factor, precise control of the average refractive index within .+-.0.01 can be achieved and traveling-wave semiconductor laser amplifiers and superluminescent LEDs with facet reflectivities of order 10.sup.--5 or less are obtained reproducibly for a single layer coating. Multilayer AR coatings can also be fabricated by using the invention technique with different combination of materials. The coatings can further be fine tuned by using wet etching or an ion gun mounted in the same deposition chamber for film thinning.
摘要:
A nanophotolithography mask includes a layer of an electrically conductive optically opaque material deposited on a mask substrate in which regular arrays of sub-wavelength apertures are formed. The plasmonic excitation in the layer perforated with the sub-wavelength apertures arrays under the light incident on the mask produces high resolution far-field radiation patterns of sufficient intensity to expose a photoresist on a wafer when propagated to the same. The fill-factor of the mask, i.e., the ratio of the total apertures area to the total mask area, may lead to a significant increase in mask manufacturing throughput by FIB or electron beam “writing”. The mask demonstrates the defect resiliency and ability to imprint coherent clear features of nano dimensions and shapes on the wafers for integrated circuits design.
摘要:
The output optical beam from an angled-facet semiconductor laser diode is made to propagate parallel to the optical axis of the laser package with low optical back-reflection. In this way, the angled-facet devices are made compatible with conventional semiconductor laser packages enabling them to be economically incorporated in a wide-range of external semiconductor lasers and amplified spontaneous emission sources. The parallel beam is achieved by tilting the laser diode with respect to the front and back surfaces of the package.
摘要:
A method and a resulting device for mounting a semiconductor to a submount by depositing a first layer of a first metal solder having a selected first melting point and corresponding thickness onto a surface of the semiconductor. Depositing a second layer of a second metal solder having a selected second melting point higher than the first melting point and a corresponding selected thickness onto a surface of the submount. Disposing the semiconductor surface and submount surface in confronting intimate contact and heating the submount and semiconductor to a temperature greater than the first temperature and lower that the second temperature for initiating and promoting liquid interdiffusion between the first and second solders.
摘要:
The I.sub.2 bound exciton in cadmium sulfide (bound to a neutral donor) is a very efficient radiator, providing low switching energy and fast switching times for an ON and OFF optical bistable device, desirable for all-optical signal processing applications. The optical bistable device for light at a given wavelength includes a Fabry-Perot cavity having a pair of opposed mirrored surfaces. A direct bandgap semiconductor, such as CuCl, CdSe, CdS, and GaAs having a bound exciton, is located within the cavity. The cavity is tuned near resonance of the light. The bound exciton has a coefficient of absorption tuned near resonance. A light beam of varying intensity is applied from without the cavity to one of the surfaces. The semiconductor has both an index of refraction and a coefficient of absorption that vary with the magnitude of applied light. Thus, light applied thereto passes through the device either substantially unimpeded or impeded, dependent upon its magnitude.
摘要:
A method for enhancing stability of a three wheel vehicle having a pair of front wheels and a single rear wheel, each of the wheels having a tire with a tire grip threshold. The method including deploying an electronic stability system (ESS) on the vehicle, providing the ESS with input from various vehicle sensors related to the longitudinal and lateral acceleration of the vehicle, causing the ESS to determine whether (i) a precursory condition indicative of a wheel lift exists and (ii) the tire grip threshold of any of the tires has been exceeded; and when a precursory condition indicative of a wheel lift exists and the tire grip threshold of none of the tires has been exceeded, causing the ESS to reduce the longitudinal acceleration of the vehicle by a first amount less than that which would cause the tire grip threshold of any of the tires to be exceeded.
摘要:
A vehicle comprising a seat defining a driver seat portion and a passenger seat portion, an electronic stability system, adapted to receive inputs from a load sensor, a wheel rotation sensor and a lateral acceleration sensor, the electronic stability system adapted to provide outputs to at least one of the brake system for braking the vehicle, and the engine control unit to change the power output transmitted to the wheels by the engine, the electronic stability system using a first calibration to determine the outputs when the load sensor is in a non-loaded state and a second calibration to determine the outputs when the load sensor is in a loaded state.
摘要:
A method for enhancing stability of a three wheel vehicle having a pair of front wheels and a single rear wheel, each of the wheels having a tire with a tire grip threshold. The method including deploying an electronic stability system (ESS) on the vehicle, providing the ESS with input from various vehicle sensors related to the longitudinal and lateral acceleration of the vehicle, causing the ESS to determine whether (i) a precursory condition indicative of a wheel lift exists and (ii) the tire grip threshold of any of the tires has been exceeded; and when a precursory condition indicative of a wheel lift exists and the tire grip threshold of none of the tires has been exceeded, causing the ESS to reduce the longitudinal acceleration of the vehicle by a first amount less than that which would cause the tire grip threshold of any of the tires to be exceeded.