Abstract: Spot-size conversion for interfacing a first optical element having a higher refractive index to a second optical element having a lower refractive index is achieved through the use of two optical star couplers coupled to each other through a plurality of optical paths embedded in a planar waveguide. The beam from the high refractive index element is introduced into a high numerical aperture (NA) star coupler, which directs the beam through a plurality of optical paths to a second star coupler with a lower numerical aperture than the first star coupler so that its output spot-size is larger. The output port of the second star coupler is interfaced to the lower refractive index element. Wavelength selection can be provided by making non-zero path-length differences between adjacent optical paths between the two star couplers.

Abstract: A high power multi-frequency laser includes a laser cavity defined by reflective elements, a frequency routing device in the cavity comprising a plurality of frequency selective pathways, a first set of optical amplifiers optically coupled to a first end of the frequency routing device, and a second set of optical amplifiers optically coupling a second end of the frequency routing device and a first one of the reflective elements. The high power multi-frequency laser further includes a power combiner. The power combiner is optically coupled to the first set of optical amplifiers and a second one of the reflective elements and combines the outputs of the first set of optical amplifiers such that a common output for the multi-frequency laser is provided. The common output of the present invention provides a single output from the multi-frequency laser having a high output coupling efficiency.

Abstract: A planar lightguide circuit (PLC) phase shifter is fabricated on a chip which exhibits reduced thermal crosstalk by reducing the thermal resistance between the waveguide cores and the thermal “ground” (e.g., a heat sink) compared to the thermal resistance between the waveguide cores. This is accomplished by removing some of the glass from the backside of the chip over a small area under the phase shifters, depositing metal on the backside, and soldering it to a copper block heat sink.

Abstract: Temperature compensation of a wavelength-division-multiplexed (WDM) passive optical network (PON) communication system uses power measurements from each of it remote nodes (RNs) to adjust the frequency of an associated multifrequency laser (MFL). Changes in the power level at each RN caused by frequency drift of its waveguide grating router (WGR), due to changes in the WGR temperature, is determined by monitoring the power level received at each RN and corrected by appropriate changes in the temperature of the associated MFL. The WGR uses one output port (e.g., channel 1) which is looped-back through the WGR a second time to increase the temperature sensitivity of the power measurements. A temperature-control algorithm controls the temperature of the MFL as a function of changes in the received power at the WGR.

Abstract: A hybrid integrated optical transmitter comprising a wavelength selectable laser (WSL) source coupled to an optical amplifier/modulator has been realized. Disposed between the optical combiner and the optical amplifier/modulator is an “optical isolator.” The optical isolator includes at least a Faraday rotator and, either solely or in combination with a single polarizer and/or half-wave plate is used to selectively rotate and pass polarized light egressing from the wavelength selectable laser source. Optical isolation is achieved by the egressing radiation from and back reflections incident on the laser source being at two mutually exclusive orthogonal polarization states or by the reflections being totally extinguished. Advantageously, the laser source is unresponsive to orthogonally polarized light, and hence any unwanted back reflections do not substantially affect the operating characteristics of the laser(s).

Abstract: Opto-mechanical arrangements for use in light wave paths use actuator wires of a material, such as NiTi, whose length can be shortened by flowing heating current in the wire. The arrangements include switches and attenuator assemblies.

Abstract: In accordance with the present invention, apparatus for and method of operating an optical signal monitor is disclosed for providing rapid monitoring of optical signals using a high speed optical modulator. One illustrative optical signal monitor includes (1) a Mechanical AntiReflective Switch (MARS) optical modulator (signal chopper) capable of operating at 10 MHz rates and having a detection bandwidth greater than 100 kHz and (2) a synchronous detector using lock-in detection in a 1550 nm-band WDM optical monitor to enhance detection sensitivity by greater than 30 dB compared to direction detection methods. According to another embodiment, the optical monitor can be used to control adaptive optical amplifier units or equalizer units of a wavelength division multiplexed (WDM) system.

Abstract: The specification describes lightwave systems with remotely powered photoelectric generators. Optical power transmitted through the fiber is incident on a remotely located photodiode array. High power conversion efficiency coupled with a specially designed diode array generates sufficient power to operate electromechanical or electrooptic apparatus in the remote station. Long wavelength photodiodes in a circular or polygonal circularly symmetric array are serially connected to increase the voltage to practical operating levels. The photodiodes are fabricated to allow back lighting of the array. The bottom contact layer is made transparent to the wavelength of the power signal. This arrangement allows the contact area to extend over the entire front surface of the diode to reduce contact resistance. It also gives nearly optimum fill factor. The front surface may be metallized so the incident light undergoes a double pass through the absorbing layer.

Abstract: A multifrequency laser (MFL) eliminates nonlinearities produced in the "shared" waveguide of the MFL laser (the section in which all the lightwaves from all the lasers pass) by either making the shared waveguide as short as possible to mimimize the production of mixing product signals or using a channel spacing that is unequal such that any mixing product signals formed from the multifrequency optical laser signal do not overlap in frequency with any of the signals of the multifrequency optical laser signal.