Abstract: This disclosure relates to the layout of optical components included in a photonics integrated circuit (PIC) and the routing of optical traces between the optical components. The optical components can include light sources, a detector array, and a combiner. The optical components can be located in different regions of a substrate of the PIC, where the regions may include one or more types of active optical components, but also may exclude other types of active optical components. The optical traces can include a first plurality of optical traces for routing signals between light sources and a detector array, where the first plurality of optical traces can be located in an outer region of the substrate. The optical traces can also include a second plurality of optical traces for routing signals between the light sources and a combiner, where the second plurality of optical traces can be located in regions between banks of the light sources.

Abstract: This disclosure relates to the layout of optical components included in a photonics integrated circuit (PIC) and the routing of optical traces between the optical components. The optical components can include light sources, a detector array, and a combiner. The optical components can be located in different regions of a substrate of the PIC, where the regions may include one or more types of active optical components, but also may exclude other types of active optical components. The optical traces can include a first plurality of optical traces for routing signals between light sources and a detector array, where the first plurality of optical traces can be located in an outer region of the substrate. The optical traces can also include a second plurality of optical traces for routing signals between the light sources and a combiner, where the second plurality of optical traces can be located in regions between banks of the light sources.

Abstract: This disclosure relates to the layout of optical components included in a photonics integrated circuit (PIC) and the routing of optical traces between the optical components. The optical components can include light sources, a detector array, and a combiner. The optical components can be located in different regions of a substrate of the PIC, where the regions may include one or more types of active optical components, but also may exclude other types of active optical components. The optical traces can include a first plurality of optical traces for routing signals between light sources and a detector array, where the first plurality of optical traces can be located in an outer region of the substrate. The optical traces can also include a second plurality of optical traces for routing signals between the light sources and a combiner, where the second plurality of optical traces can be located in regions between banks of the light sources.

Abstract: An optical sensor apparatus includes an optically transmissive structure (e.g., a prism) having two planar faces and a third planar face that connects the two planar faces, two or more light sources located outside the structure, and a photodetector array located outside the prism. The structure, light sources, and photodetector array are configured such that light from the light sources that is totally internally reflected at an optical interface between the prism and a sample outside the structure proximate one of the two planar faces is incident on a portion of the photodetector array that depends on a refractive index of the sample. The light sources are positioned with respect to the structure and photodetector array such that the totally internally reflected light from each light source corresponds to a different range of refractive index of the sample and maps to a corresponding portion of the photodetector array.

Abstract: An optical sensor apparatus includes an optically transmissive structure having planar first, second, and third faces, two or more light sources located outside the structure adjacent the first face, and a photodetector array located outside the prism adjacent the first face. The structure, light sources, and photodetector array are configured such that light from the light sources that is totally internally reflected at an optical interface between the prism and a sample outside the structure proximate the second face is reflected at the third face and incident on a portion of the photodetector array that depends on a refractive index of the sample. The light sources are positioned with respect to the structure and photodetector array such that the totally internally reflected light from each light source corresponds to a different range of refractive index of the sample and maps to a corresponding portion of the photodetector array.

Abstract: An optical sensor apparatus includes an optically transmissive structure (e.g., a prism) having two planar faces and a third planar face that connects the two planar faces, two or more light sources located outside the structure, and a photodetector array located outside the prism. The structure, light sources, and photodetector array are configured such that light from the light sources that is totally internally reflected at an optical interface between the prism and a sample outside the structure proximate one of the two planar faces is incident on a portion of the photodetector array that depends on a refractive index of the sample. The light sources are positioned with respect to the structure and photodetector array such that the totally internally reflected light from each light source corresponds to a different range of refractive index of the sample and maps to a corresponding portion of the photodetector array.

Abstract: An optical sensor apparatus includes an optically transmissive structure having planar first, second, and third faces, two or more light sources located outside the structure adjacent the first face, and a photodetector array located outside the prism adjacent the first face. The structure, light sources, and photodetector array are configured such that light from the light sources that is totally internally reflected at an optical interface between the prism and a sample outside the structure proximate the second face is reflected at the third face and incident on a portion of the photodetector array that depends on a refractive index of the sample. The light sources are positioned with respect to the structure and photodetector array such that the totally internally reflected light from each light source corresponds to a different range of refractive index of the sample and maps to a corresponding portion of the photodetector array.

Abstract: Switchable power combining is provided using a tunable arrayed waveguide grating (AWG) as the combining element. The AWG has two or more inputs and two or more outputs. Each AWG input is bi-directionally coupled to a corresponding laser source, and each laser source has substantially the same gain spectrum. All sources are coupled to a selected one of the AWG outputs, without substantial coupling of the sources to any other AWG output. The AWG is tunable, such that any one of its outputs can be thus selected. The selected output provides optical feedback, thereby feedback stabilizing the emission wavelengths of the sources to values suitable for single-mode combining. According to a further aspect of the invention, a piezo-electrically tunable AWG is provided. The AWG has a piezo-electric transducer bonded to the waveguide array section of the AWG. Strain induced in the waveguide array by the transducer can alter optical path lengths of the waveguide, thereby tuning the AWG.

Abstract: Optical waveguide devices characterized by low loss for a fundamental mode and high loss for higher order modes are disclosed. The high loss is sufficiently high that the waveguide is effectively single-moded.

Abstract: Quasi-phasematching design to provide an approximation to a desired spectral amplitude response A(f) is provided. An initial phase response ?(f) corresponding to A(f) is generated. Preferably, d2?(f)/df2 is proportional to A2(f). Alternatively, ?(f) can be a polynomial in f. A function h(x) is computed such that h(x) and H(f)=A(f)exp(i?(f)) are a Fourier transform pair. A domain pattern function d(x) can be computed by binarizing h(x) (i.e., approximating h(x) with a constant-amplitude approximation). In some cases, the response provided by this d(x) is sufficiently close to A(f) that no further design work is necessary. In some embodiments of the invention, the need for binarization can be reduced or eliminated by providing amplitude modulation of the effective nonlinearity.

Abstract: A frequency-converted laser may be made with a non-linear material having a surface coated with an anti-reflection coating by measuring an absorbance of the anti-refection coating, and using the non-linear crystal for frequency conversion in the laser if the absorbance measured is less than a rejection threshold of about 100 parts-per-million or less.

Abstract: Methods and apparatus for managing thermal loads on a laser gain medium and for boosting the output power of a diode pumped laser are disclosed. The short-term average pumping power to the gain medium is increased, to provide a burst of pumping energy to the laser gain medium. A subsequent short-term reduction in the average pumping power then allows the gain medium to cool to a desired state steady level. The average pumping power is then increased to maintain this steady state level until the next burst is desired. For example, a pulse of current may be applied to a laser diode at a first current level I1 for a first time interval ?t1, where I1 exceeds a nominal current value Inom by an amount ?I1. The current to the laser diode is reduced to a second current level I2 for a second time interval ?t2, where Inom exceeds I2 by an amount ?I2. To balance the thermal load on the diode an integral of ?I1 over the time ?t1 is approximately equal in magnitude to an integral of ?I2 over the time ?t2.

Abstract: The use of <100>-oriented crystals as gain media in lasers and optical amplifiers is disclosed. In a laser, a substantially <100>-oriented crystal, such as <100> YAG can be disposed within an optical cavity as a gain medium. The crystal is orientated such that a <100> plane is substantially perpendicular to a direction of beam propagation within the crystal. A pump source provides pumping energy to a pumped region of the crystal. The use of a substantially <100>-oriented crystal can reduce depolarization loss and thermal lens effects if an absorbed power of the pumping energy is less than or equal to about 1000 watts of pumping radiation and/or a cross-sectional overlap between a beam of radiation propagating through the crystal and the pumped region is greater than about 20% of a cross-sectional area of the pumped region.

Abstract: An optical resonator has a piezoelectric element attached to a quasi-monolithic structure. The quasi-monolithic structure defines an optical path. Mirrors attached to the structure deflect light along the optical path. The piezoelectric element controllably strains the quasi-monolithic structure to change a length of the optical path by about 1 micron. A first feedback loop coupled to the piezoelectric element provides fine control over the cavity length. The resonator may include a thermally actuated spacer attached to the cavity and a mirror attached to the spacer. The thermally actuated spacer adjusts the cavity length by up to about 20 microns. A second feedback loop coupled to the sensor and heater provides a “coarse” control over the cavity length. An alternative embodiment provides a quasi-monolithic optical parametric oscillator (OPO). This embodiment includes a non-linear optical element within the resonator cavity along the optical path.