Abstract:
A method and apparatus to analyze the aerial image of an optical system using a subwavelength slit. A slit configuration yields a higher signal-to-noise ratio than that achievable with a round aperture. The slit also allows the polarization of the aerial image to be analyzed. In an alternative embodiment a tunneling slit is used. The tunneling slit comprises an optically transparent ridge-like structure mounted to a substrate, the combined structure covered by a thin, planar metal film.
Abstract:
PROBLEM TO BE SOLVED: To measure birefringence in a short time using a simple constitution. SOLUTION: The apparatus for measuring birefringence includes an incident unit for making an approximately circularly polarized light be incident on a sample, a Stokes meter for detecting the polarization state of the light from the sample, and an arithmetic part for calculating the birefringence of the sample on the basis of the Stokes parameter outputted from the Stokes meter. COPYRIGHT: (C)2004,JPO&NCIPI
Abstract:
Embodiments include a method and apparatus used for automatic bias stabilization of a DP IQM based on MZM for transmitting DP-QPSK optical data and/or DP-16QAM optical data. The apparatus simultaneously dithers DC-bias voltages of in-phase child, quadrature-phase child, and parent MZMs with three different dither patterns in time-domain which are mutually orthogonal to each other in the frequency-domain for X and Y polarization IQ modulators. Tap monitor photodiodes detect an interference term between these three dither patterns for each polarization. The interference term is sampled using an ADC in the time domain. The time-synchronous detection method may solve a set of three simultaneous linear partial differential equations with three unknowns to compute controlled DC-bias voltages to set on the respective MZM with a solution set which may iteratively converge to a unique solution, thereby biasing the child MZM in dual-polarization IQM to transmission minimum and parent MZM in quadrature transmission.
Abstract:
A stabilisation system for stabilising an output of a controllable light or laser source comprises a randomizer for randomizing light from the controllable light or laser source to generate a speckle pattern; a detector for detecting the speckle pattern to determine one or more properties of the light and/or changes in one or more properties of the light; and a controller for controlling the controllable light or laser source based on the determined one or more properties of the light and/or changes in one or more properties of the light.