Signal beam

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

Optical signal amplification at 1.3 μm by two-wave mixing in InP:Fe

Abstract: Two-wave mixing experiments demonstrate amplification of optical signals using the photorefractive effect in InP:Fe. Signal beam amplification was obtained at both 1.06 mu m and 1.32 mu m with gains of 13 dB/cm and 11 dB/cm, using alternating electric fields of up to +or-10/sup 4/ V/cm. Differential amplification at data rates exceeding the material response time is demonstrated.

System for transmitting a beam in the air

Abstract: A system for transmitting information with a coherent beam being propagatable in the air is arranged to include a transmitting device having a modulator and an emitting circuit and a receiving device having a generator, a mixer, a frequency discriminating circuit, and reproducing circuit. The modulator modulates a reference light frequency (wavelength) or phase of a coherent beam to be emitted from a light source according to the signal. The emitting circuit emits the modulated beam as a divergent beam having such a power density as being safe to human eyes. The generator generates a coherent locally oscillated beam. The mixer mixes the signal beam with the locally oscillated beam and photoelectric-converts the mixed beam. The frequency discriminating circuit frequency-discriminates the a.c. component of the photoelectric-converted output. The reproducing circuit reproduces a signal from the output of frequency discriminating circuit. Any one of the transmitting device and the receiving device has a function of keeping a relative light frequency difference (wavelength difference) between the signal beam and the locally oscillated beam constant.

Rubidium titanyl arsenate difference-frequency generation and validation of new Sellmeier coefficients

Abstract: Rubidium titanyl arsenate (RTA), a crystallographic isomorph of potassium titanyl phosphate, shows promise for nonlinear-frequency generation throughout the 1–5-µm spectral region. Difference-frequency generation in an RTA crystal produced tunable output in the 3.2–4.2-µm wavelength range. A single 1.064-µm Nd:YAG laser pumped both a LiNbO3 optical parametric oscillator used to generate a tunable signal beam and the RTA crystal used for difference-frequency generation. Conversion efficiencies were limited to 4% primarily by the large beam divergence of the signal beam. Phase-matching measurements were in excellent agreement with new IR-corrected RTA Sellmeier equations based on refractive-index measurements.

Complete switching in a three-terminal Sagnac switch

Abstract: A three-terminal all-optical fiber switch based on a fiber Sagnac interferometer is described The use of polarization components allows the construction of a switch in which the control beam and signal beam are isolated (ie the device is three terminal) and which is cascadable (the device output can drive its inputs) The interaction length need not be limited by the walkoff length in the fiber, as cross-splices can be made in the birefringent fiber to permit multiple passes Contrast ratios as high as 40:1 have been demonstrated in a switch driven by an amplified laser diode >

Method and device for measuring the thickness of thin films near a sample's edge and in a damascene-type structure

Abstract: A method for measuring a structure that contains overlying and underlying films in a region where the overlying film's thickness rapidly decreases until the underlying film is exposed (e.g., an edge-exclusion structure). The method includes the steps of: (1) exciting acoustic modes in a first portion of the region with at least one excitation laser beam; (2) detecting the acoustic modes with a probe laser beam that is either reflected or diffracted to generate a signal beam; (3) analyzing the signal beam to determine a property of the structure (e.g., the thickness of the overlying layer) in the first portion of the region; (4) translating the structure or the excitation and probe laser beams; and (5) repeating the exciting, detecting, and analyzing steps to determine a property of the structure in a second portion of the region.