Signal beam

About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.

Ghost Imaging Using Orbital Angular Momentum

Abstract: We present a novel encoding scheme in a ghost-imaging system using orbital angular momentum. In the signal arm, object spatial information is encoded as a phase matrix. For an N-grey-scale object, different phase matrices, varying from 0 to π with increment π/N, are used for different greyscales, and then they are modulated to a signal beam by a spatial light modulator. According to the conservation of the orbital angular momentum in the ghost imaging system, these changes will give different coincidence rates in measurement, and hence the object information can be extracted in the idler arm. By simulations and experiments, the results show that our scheme can improve the resolution of the image effectively. Compared with another encoding method using orbital angular momentum, our scheme has a better performance for both characters and the image object.

Single-mode KTiOPO4 optical parametric oscillator.

Abstract: A tunable KTiOPO4 optical parametric oscillator (OPO) operating in a single longitudinal mode of its resonator is described. Single-mode operation has been achieved by use of an intracavity Fabry–Perot etalon in a short-length OPO resonator. The crystal is pumped by the second harmonic of an injection-seeded Nd:YAG laser. The tuning range observed with a crystal cut at 60° is 0.75–0.87 μm for the signal beam and 1.83–1.37 μm for the idler beam. The linewidth of the OPO is approximately 200 MHz (0.0066 cm−1), which is close to the Fourier-transform limit. The total output energy was measured to be as much as 0.6 mJ per pulse.

Tunable Dual-Wavelength, Continuous-Wave, Mid-Infrared Generation Using Intracavity Difference Frequency Mixing in PPLN-Based Optical Parametric Oscillator

Abstract: We report on a widely tunable, dual-wavelength, continuous-wave, mid-infrared optical parametric oscillator (OPO), pumped by a dual-wavelength fiber source that was realized by combining two fiber lasers in series. The OPO was designed as a four-mirror singly resonant cavity, in which a periodically poled lithium niobate (PPLN) crystal was used as nonlinear crystal. Two idler emissions with different wavelengths were observed, one being basically fixed at 3140 nm and the other being tunable from 3227 to 3413 nm. Under the maximum pump power, the total idler power was over 6 W and the corresponding pump-to-idler slope efficiency reached 11.4%. The generated signal beam had just one central wavelength around 1600 nm. Through theoretical analysis and experimental verification, it was analyzed that two nonlinear processes, OPO and intracavity difference frequency generation (DFG), simultaneously occurred in the resonant cavity. The experimental phenomena revealed large widened DFG gain spectrum, which was in absolute contrast to simulation results based on classical DFG theory. It indicated great potential in practical application such ultra-wide nonlinear frequency conversion.

Optical transmission device

Abstract: An optical transmission device capable of preventing deterioration in the transmission quality of a signal beam A wavelength-multiplexed signal beam from a transmission path is split by a splitter, and the split signal beams are input to first and second optical paths, respectively An add/drop unit for adding/dropping a wavelength-multiplexed signal beam is removably insertable in the second optical path A switch outputs the wavelength-multiplexed signal beam, received from one of the first and second optical paths, to an optical amplifier The optical amplifier amplifies the wavelength-multiplexed signal beam output from the switch and outputs the amplified signal beam to a subsequent circuit A supervisory controller collects alarm information from the optical transmission device as well as from other optical transmission devices, and controls the switch in accordance with the collected alarm information such that the wavelength-multiplexed signal beam from the second optical path is input to the optical amplifier

Furnace control apparatus using polarizing interferometer

Abstract: A system for non-destructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading.