摘要:
A method allowing reliable routing of individual optical carriers through an optical network is disclosed. Routing information is impressed on individual carriers by a method known as subband quadrature coding (SQC). The optical carrier is modulated at a first frequency, and at a first intensity to impress application data on the carrier. The carrier is additionally modulated at a second frequency, preferably two orders of magnitude less than the first frequency, and at a second intensity less than the first intensity to impress management data on the carrier for routing the carrier through an optical communications network, from a source to a destination. According to the method, the management data is continuously impressed upon the carrier during transmission of the application data. The optical carrier is multiplexed onto the fiber optic communications line, and upon reaching a first node, the carrier is demultiplexed and an intensity sample of the carrier is detected. The management data is then separated out with a low pass filter, whereupon in response the method directs the carrier signal according to the management data.
摘要:
An iris imaging and illumination system is used to resolve and record the fine musculature features of an iris. The system can improve the quality of an iris image and facilitate the image capturing process by focusing illumination on an ocular area of a subject. By limiting illumination of other parts of a face, reflections from the face are reduced. The system has a compact physical arrangement by placing the illumination sources proximate to one another and splaying them in order to focus illumination on the ocular areas of a subject.
摘要:
An intracavity doubled single longitudinal mode laser is disclosed which provides stable (i.e., low amplitude variation in its output beam intensity), efficient operation. An associated method is also disclosed. The laser includes an input mirror and an output mirror defining a resonant cavity and a light path within the resonant cavity and between the mirrors. The output mirror is configured to be substantially transparent to an output wavelength produced within the cavity. A lasant material is positioned in the light path for producing light at a desired fundamental wavelength and possibly other, unwanted wavelengths. Polarizing element and a type I doubling material are also positioned in the light path. During operation of the laser, the polarizing element polarizes the desired fundamental wavelength as well as the unwanted wavelengths of light produced by the lasant material. The type I doubling material then produces output wavelengths at twice the frequency of any wavelengths passing therethrough. The type I doubling material and the polarizing element are arranged such that they cooperate in a way which causes the unwanted wavelengths to be subjected to losses which result in the unwanted wavelengths being extinguished while the desired fundamental wavelength is subjected to a level of loss above a lasing threshold so that the desired fundamental wavelength lases, thereby producing the desired output wavelength. In one aspect of the invention, blue light may be produced as the output wavelength with an efficiency which has not been seen previously.
摘要:
A method and system are disclosed for synthesizing an electric field. In accordance with exemplary embodiments of the present invention, an electric field that changes across a distance in space is synthesized by applying voltage levels at several locations independently of one another. The independence in voltage levels allows the electric field that is synthesized to be made periodic or aperiodic. Such a synthesized electric field can be changed at any time for use in, for example, a tunable laser. According to an exemplary embodiment, the electric field is used to change the refractive index of an electro-optic substance in an optical filter. Such an optical filter can be used as part of, for example, a wavelength agile laser, an optical add drop multiplexer, an optical switch, or the like. Such an optical filter can also be used for dynamic power balancing, dynamic gain equalization, or the like.
摘要:
An electric field that changes across space is synthesized, by applying voltage levels independent of one another at several locations. The independence in voltage levels allows the electric field that is synthesized to be made periodic or aperiodic. Such a synthesized electric field may be changed at any time for use in, for example, a tunable laser. In one embodiment, the voltage levels are oversampled, although in other embodiments the voltage levels need not be oversampled, e.g. if the to-be-synthesized electric field is aperiodic. Also, in one embodiment, the electric field is used to change the refractive index of an electro-optic substance (such as lithium niobate) in an optical filter. Such an optical filter can be used as part of a wavelength agile laser or in an optical add drop multiplexer or in an optical switch. Such a filter can also be used for dynamic power balancing and/or for dynamic gain equalization.
摘要:
As will be described in more detail hereinafter, an intracavity doubled single longitudinal mode laser is disclosed which provides stable (i.e., low amplitude variation in its output beam intensity), efficient operation in conjunction with a highly advantageous decoupled alignment configuration. An associated method is also disclosed. A lasant material is positioned in the light path of the laser for producing light at a desired fundamental wavelength and possibly other, unwanted wavelengths. Polarizing means is also positioned in the light path for polarizing the desired fundamental wavelength and the unwanted wavelengths of light. In addition to the polarizing means, birefringent means is positioned in the light path on one side of the polarizing means for selectively subjecting the unwanted wavelengths to losses in cooperation with the polarizing means such that the unwanted wavelengths are extinguished while the desired fundamental wavelength is subjected to a level of loss above a lasing threshold so that the desired fundamental wavelength lases. A type I doubling material is adjustably arranged in the light path for producing the doubled frequency light at twice the frequency of the desired fundamental frequency passing therethrough and for adjustment of phase matching which establishes an efficiency at which the doubled light frequency is produced. The birefringent means and the type I doubling material are arranged on opposite sides of the polarizing means along the light path so as to substantially decouple wavelength selection performed by adjusting the birefringent means from the phase matching adjustment performed by adjusting the type I doubling material.
摘要:
An iris imaging and illumination system is used to resolve and record the fine musculature features of an iris. The system can improve the quality of an iris image and facilitate the image capturing process by focusing illumination on an ocular area of a subject. By limiting illumination of other parts of a face, reflections from the face are reduced. The system has a compact physical arrangement by placing the illumination sources proximate to one another and splaying them in order to focus illumination on the ocular areas of a subject.
摘要:
A single mode laser is described including a gain swept configuration. The laser includes an input mirror and an output mirror defining a resonant cavity and a light path within the resonant cavity and between the mirrors. A laser gain material is positioned at a predetermined location along the light path and arranged with a predetermined gain length along the light path for producing light at the desired output wavelength such that a standing wave pattern at the desired output wavelength is formed within the cavity between the mirrors. The gain material is capable of producing light at other, unwanted wavelengths which can potentially form other standing wave patterns. All of the wavelengths are produced with some gain. Oscillation means is provided for varying the length of the light path which, by varying the length of the light path a sufficient amount, causes the standing wave pattern of the desired output wavelength to oscillate as a traveling wave along the light path such that the standing wave pattern moves through at least substantially the entire gain length of the gain material along the light path for extracting substantially all of the available gain from the gain material, whereby only the desired output wavelength lasers.
摘要:
A laser comprising a laser cavity (13) having reflectors at each end of an optical path, a first layer of gain material (15) and a second layer of a second material (14, 16) disposed along the optical path, wherein the first and second layer are directly optically contacted to one another at associated faces. Also, a laser comprising a laser cavity having a layer of gain material (15), and second and third crystals (14,16) having anisotropic refractive indices disposed along an optical path, the laser being oscillatory in a preferred mode having a particular orientation of polarization, the second crystal (16) being oriented with respect to the path to cause no appreciable net depolarisation of the preferred mode, and the third crystal (14) being arranged such that the preferred mode is transmittable therethrough with minimal refraction.
摘要:
A laser 10 comprises a pump source 11, a resonator 13 including an etalon of gain material 15, and means 12 to focus the pump source 11 output onto one end 14 of the resonator 13 as a spot having a diameter in the range 50-150 .mu.m. The resonator 13 includes substantially parallel end faces 14,19 having a relative taper better than 0.25 milliradians, and the end faces 14,19 are substantially free of scratches greater than 10 .mu.m in size and pits greater than 5 .mu.m in size. A thermally induced microlens 22 is formed at the surface 14 of the gain material 15.