Abstract: An optical appliance includes at least one input waveguide and a first free space region connected to the input waveguide. A first plurality of waveguides is connected to the first free space region. An optical grating, which is connected to the first plurality of waveguides, includes a plurality of unequal length waveguides that are divided into at least three waveguide groups. Adjacent waveguides that belong to the same group have a substantially constant path length difference between them while adjacent waveguides belonging to different groups of waveguides have a path length difference between them that differs from the constant path length difference by an odd integer multiple of one-half a preselected wavelength. A second plurality of waveguides is connected to the optical grating and a second free space region is connected to he second plurality of waveguides. At least one output waveguide is connected to the second fee space region.

Abstract: An optical passband filter having a frequency transition that is several of orders of magnitude narrower than prior optical filters includes two frequency routing devices. The first frequency routing device has one input for receiving the input signal and at least N outputs, where N corresponds to the number of frequencies that compose the input signal. The N outputs of the first frequency routing device are each coupled to inputs of a second frequency routing device. The outputs of the second frequency device each correspond to one of the selected output frequency bands into which the input signal is to be divided. A multiplexed input signal containing several different frequency channels is divided into bands that are each directed to respective outputs of the second frequency routing device. The frequency transition between the various bands may be as small as the frequency resolution between adjacent outputs of the first frequency routing device.

Abstract: An optical device includes a semiconductor optical amplifier and a lens for receiving optical energy from the optical amplifier. The lens and the optical amplifier are monolithically integrated on a common substrate. The optical amplifier may be of the type having a tapered active region. Rather than an optical amplifier, a semiconductor laser may be integrated with the lens. The lens may be formed by changing the refractive index of the waveguide core which is formed in the semiconductor material. This refractive index change may be produced by changing the thickness of a portion of the waveguide core layer.

Abstract: A semiconductor device is provided that includes an optical cavity that is designed to provide a prescribed resonant optical wavelength. The optical cavity includes a mirror structure deposited on top of a substrate and a multi-layer region such as an electroabsorptive region, for example, deposited over the mirror structure. A partial antireflective coating is deposited over the multi-layer region. The mirror structure and the multilayer region have a thickness variation sufficient to yield a resonant optical wavelength that deviates from the prescribed resonant wavelength. The partial antireflective coating has a non-uniform thickness variation that causes the resonant optical wavelength to shift substantially toward the prescribed resonant optical wavelength.

Abstract: A method for synchronizing an etalon to a preselected set of optical frequencies includes the step of generating a transmission spectrum for an etalon having a characteristic free spectral range that is a function of its effective length. The optical frequencies for the transmission spectrum are provided by two optical reference frequencies such as produced by a first and second frequency locked laser. The effective length of the etalon is set in relation to the optical reference frequencies.

Abstract: A monolithically integrated optical filter which is rapidly tunable over a wide optical frequency range includes an input frequency router connected to an output frequency router by means of selectively activatable transceivers. The transceivers are formed from optically active sections and electronic controllers that selectively modulate, demodulate and amplify a desired one or more of a plurality of multiplexed input optical frequencies. This filter is economical to construct and is useful in high capacity, high speed optical communications networks.

Abstract: A method and apparatus for producing high quality optical pulse trains at a high repetition rate first phase modulates a cw optical signal with an external phase modulator. The central optical frequencies (i.e., the carrier frequency and at least one pair of sidebands) of the phase modulated signal are then removed from the signal. Each of the remaining side-bands that have not been removed independently form an optical pulse train of the desired transform-limited pulses.

Abstract: A tunable waveguide grating includes a plurality of N waveguides which define N optically transmissive pathways. A plurality of (N-1) electrodes are arranged in the pathways such that the kth pathway contains (k-1) electrodes, where 0<k<N. As a result of this arrangement, an optical signal propagating through the kth pathway will experience a phase shift provided by each of the (k-1) electrodes arranged in that pathway. Consequently, in contrast to prior tunable optical gratings, each electrode may contribute a phase shift to the portions of the signal propagating through several waveguides and hence as the number of waveguides increases no individual electrode is required to produce relatively large phase shifts.

Abstract: A flashlight is disclosed comprising a light source and a reflector for collimating the light emitted by the light source to form a collimated light beam. An electro-optically controlled region is disposed forwardly of the light source, the collimated light beam being incident upon and passing through the electro-optic region. The electro-optic region may be operated in at least two states. In a first embodiment, and in a first state, the electro-optic region does not substantially affect the collimation of the light beam incident thereon, and the flashlight produces a spot beam. Also in the first embodiment, and in a second state, the electro-optic region scatters forwardly the collimated beam incident thereon, and thus the flashlight produces a well-diffused flood beam.

Abstract: We describe a technique for producing a flat passband in a wavelength multiplexer. We obtain this by combining two output waveguides, and by optimizing their parameters so as to produce a maximally flat passband with minimal loss. The optimum parameters are obtained, to a good approximation, by choosing each output waveguide so that its mode approximately matches the input waveguide mode (see page 9 on) and by choosing the spacing of the two waveguides so that the multiplexer transmission coefficient at the edges of the passband is approximately equal to the value at the center of the passband. We also include, in the multiplexer, additional waveguides that allow the center wavelength of the passband to be varied in steps of S/Q, where S is the channel spacing and .delta. is an integer exceeding the number of channels (multiple control input waveguides). As a result, we obtain a unique arrangement, suitable for realization in integrated form using waveguide arrays.

Abstract: A monolithically integrated laser which is rapidly tunable over a wide optical frequency range comprises a frequency router formed in a semiconductive wafer defining a tuned cavity. A control circuit applies electrical energy to predetermined controllably transmissive waveguides connecting the frequency routing device with reflective elements defined in the wafer. This tunes the laser to a desired one of a plurality of optical frequencies. Application of such electrical energy creates frequency selective pathways through the wafer able to support selected lasing frequencies. Additional optical amplifiers are formed in the frequency router to create lasing action in a preselected pathway. This laser is economical to construct and is useful in high capacity, high speed optical communications networks.

Abstract: A monolithically integrated laser which is rapidly tunable over a wide optical frequency range comprises a frequency router formed in a semiconductive wafer defining a tuned cavity. A control circuit applies electrical energy to predetermined controllably transmissive waveguides connecting the frequency routing device with reflective elements defined in the wafer. This tunes the laser to a desired one of a plurality of optical frequencies. Application of such electrical energy creates frequency selective pathways through the wafer able to support selected lasing frequencies. This laser is economical to construct and is useful in high capacity, high speed optical communications networks.

Abstract: A monolithically integrated wideband laser which is rapidly tunable over a wide optical frequency range comprises two series connected frequency routers of different resolutions formed in a semiconductive wafer defining a tuned cavity. A control circuit applies electrical energy to predetermined controllably transmissive waveguides connecting the frequency routing devices with reflective elements defined in the wafer. This tunes the laser to a desired one of a plurality of optical frequencies. Application of such electrical energy creates frequency selective pathways through the wafer able to support up to hundreds of selected lasing frequencies across the entire bandwidth of a semiconductive medium. This laser is economical to construct and is useful in high capacity, high speed optical communications networks.

Abstract: Checks used to effectuate commercial and private transactions may be cleared through the banking system by transporting images of those checks between sending institutions and receiving institutions in forward and reverse flow paths between banks of first deposit and payor banks. The check images are transported through a public switched telephone network which contains a special check imaging node which provides a network based check clearing service for customers of telephone network. The check imaging node receives images of checks from institutions which subscribe to this service and routes those images through the telephone network to intended subscriber and non-subscriber recipients. Transmission of check images through a public switched telephone network may completely replace existing check clearance procedures or may be used in conjunction with existing procedures.

Abstract: There is disclosed the architecture for an all optic network which employs a three level hierarchy using wavelength vision multiplexing. At the lowest level of the hierarchy are Level-0 all optical networks. The Level-0 networks are "local" broadcast networks each of which supports a plurality of access ports and each access port can hear all the local traffic transmitted by all other access ports in the same Level-0 network. Each Level-0 network shares wavelengths internally, but there is extensive reuse of wavelengths among different Level-0 networks. The next higher level, which is the intermediate level, Level-1, is essentially a wavelength router coupled with one or more of the Level-0 networks to provide a wavelength path to one or more directly connect Level-0 networks or, in combination with a Level-2 network, a light path to one or more Level-0 network outside itself.

Abstract: Previous efforts to measure polarization dependent loss of optical components have been limited in uncertainty to more than 0.01 dB. This is because the power meter used in a test set contains polarization dependent loss which adversely affects the final readings. It is here disclosed that an unpumped erbium doped fiber can convert a received polarized signal into unpolarized amplified spontaneous emission of a longer wavelength if the fiber is of sufficient length to absorb the received signal. By locating the inventive unpumped erbium doped fiber upstream of the power meter of a test set, the polarized signal to the power meter is coverted to an unpolarized signal and, therefore, the polarization dependent loss of the power meter can not influence the measurement obtained.

Abstract: In this invention, a semiconductor device designed for use as an optical amplifier is provided with three sections; an input section, a middle section and an output section. A continuous optical waveguide extends through the input section, the middle section and the output section and the three sections are electrically isolated from each other. More specifically, a semiconductor laser amplifier is electrically split into three separate sections by implanting ions of, for example, hydrogen, helium or fluorine into the areas of the semiconductor amplifier which are between the middle section and the two end sections. The ion implantation provides a high degree of electrical isolation between the various sections, but it does not alter the continuity of the optical waveguide which passes through the three sections.