A tunable wavelength-selective filter includes a glass substrate, a transparent electrode layer, a highly reflective mirror, an alignment layer, a liquid crystal layer, another alignment layer, a transparent material layer whose refractivity index is substantially equal to that of the liquid crystal layer, another highly reflective mirror, another transparent electrode layer, and another glass substrate, which are stacked in this order. An etalon cavity of the filter includes two layers, the liq...

A pendulum-like member is formed in a silicon substrate. Optical fiber portions which include endface mirrors are disposed on the substrate proper and on the pendulum member. The position of the pendulum member is adjusted by applying a voltage across the member and an adjacent section(s) of the substrate thus enabling the optical length of the device to be adjusted.

A system and method for absolute, high resolution and accurate strain measurement includes a low-coherence light source (12) transmitting light through a strain sensor (18) and into an interferometer (26). The interferometer (26) has a high-coherence light source (48) that parallels the light from the low-coherence light source (12). The output of the interferometer is detected by a photodetector (46). The photodetector (46) is connected to a phase measuring circuit (30), that is in communicatio...

A compact wavelength monitoring and control assembly for a narrow band (i.e., laser) source is provided, comprising two narrow bandpass, wavelength selective transmission filter elements of Fabry-Perot structure through which two separate collimated beams from a laser source are directed onto two photodetectors. The spacing of the multiple transmission maxima for one etalon is chosen to match that of the desired set of frequencies to be used for locking purposes. The spacing of the transmission ...

A thermally stable etalon filter includes a pair of spaced apart mirrors defining a Fabry-Perot cavity and an optical medium disposed in the cavity. The optical medium is comprised two optically transparent materials, one having a coefficient of thermal expansion that is countervailing to the coefficient of thermal change of refractive index of the other. The thicknesses of the two materials are selected so that the thermal expansion of the optical medium offsets the thermal change in the refrac...

Apparatus and methods for compensation of asymmetric mode pulling in external cavity lasers and the like. An apparatus includes a wavelength locker or etalon device to provide an asymmetric power transfer function and generate a transmission peak or peaks of asymmetric shape. The asymmetry of the transmission peak may be in the form of a steeper slope on the long wavelength side of the peak than on the short wavelength side. The asymmetry of the transmission peak or peaks may be structured to co...

A compressive force is applied to a conventional air-spaced etalon filter to fine tune the thickness of the spacers to a precise and uniform optical length. The etalon is coupled to a housing device capable of adjusting the thickness of each spacer, thereby tuning the etalon to the desired filter wavelength. The resulting assembly is permanently set to the desired parameters for direct use in optical applications.

A method and apparatus are disclosed for measuring a characteristic, e.g. spectral bandwidth, of a light beam. The apparatus may comprise an etalon for generating an interference pattern having at least one light cone, an arrangement of detector elements, the arrangement receiving a portion of the light cone and producing a signal indicative of the characteristic; and an auxiliary detector positioned to receive a portion of the light cone and produce a signal indicative of an alignment between t...

A high-precision etalon and novel method of construction thereof is presented. The etalon comprises a pair of plane-parallel flat mirrors spaced a first distance apart, a pair of plane-parallel spacers transversely attached to the pair of mirrors which operate to fix the first distance between the pair of mirrors, and a thin film mirror layer deposited on at least one of the pair of plane-parallel flat mirrors to form a laser cavity therein of a precise second distance apart. The method of const...

A semiconductor tunable laser system includes a tunable Fabry-Perot cavity and a cavity length modulator, which controls an optical length of the cavity at least over a distance corresponding to the spacings between the longitudinal modes of the laser cavity. Thus, the tunable Fabry-Perot cavity allows the laser cavity to have gain at the desired wavelength of operation while the cavity length modulator tunes the cavity length such that a longitudinal cavity mode exists at the desired wavelength...