Abstract: Optical devices and methods of fabricating thereof that include providing two different optical paths: a first optical path including a first waveguide core and a first cladding layer adjacent the first waveguide core; and a second optical path including a second waveguide core and a second cladding layer adjacent the second waveguide core. A thermo-optic coefficient (TOC) of the first waveguide core and a TOC of the first cladding layer have a same sign, for example positive, and a sign of a TOC of the second waveguide core is different than a sign of a TOC of the second cladding layer, for example, one positive and one negative. The paths may be in an Mach-Zehnder Interferometer (MZI).

Abstract: A broadband ring resonator includes a first waveguide and a second waveguide. The first waveguide is a closed loop having a first coupling section having a first width and a first curvature radius. The second waveguide includes a first section, a second coupling section, and a second section which are connected in sequence. The second coupling section has a second width and a second curvature radius. Coupling ratios of the second waveguide coupled to the first waveguide within a broadband have a similarity to each other. A coupling angle is respectively between two ends of the first coupling section and between two ends of the second coupling section, and the first and second coupling sections are separated by a coupling gap. The second curvature radius is greater than the first curvature radius. A ratio of the first width with respect to the second width ranges from 1.3 to 1.7.

Abstract: Disclosed are edge couplers having a high coupling efficiency and low polarization dependent loss, and methods of making the edge couplers. In one embodiment, a semiconductor device for optical coupling is disclosed. The semiconductor device includes: a substrate; an optical waveguide over the substrate; and a plurality of layers over the optical waveguide. The plurality of layers includes a plurality of coupling pillars disposed at an edge of the semiconductor device. The plurality of coupling pillars form an edge coupler configured for optically coupling the optical waveguide to an optical fiber placed at the edge of the semiconductor device.

Abstract: Disclosed are edge couplers having a high coupling efficiency and low polarization dependent loss, and methods of making the edge couplers. In one embodiment, a semiconductor device for optical coupling is disclosed. The semiconductor device includes: a substrate; an optical waveguide over the substrate; and a plurality of layers over the optical waveguide. The plurality of layers includes a plurality of coupling pillars disposed at an edge of the semiconductor device. The plurality of coupling pillars form an edge coupler configured for optically coupling the optical waveguide to an optical fiber placed at the edge of the semiconductor device.

Abstract: A waveguide division multiplexer and demultiplexer includes a first-stage Mach-Zehnder interferometer (MZI) and two second-stage MZIs. The first-stage MZI includes two input ends and two output ends, in which one of the inputs is configured to receive an input optical beam with a first center wavelength and a second center wavelength, and the output ends are configured to respectively transmit first-stage output optical beams respectively with the first center wavelength and the second center wavelength. One input terminals of the second-stage MZI are configured to respectively receive the first-stage output optical beams, and one output terminals of the second-stage MZI are configured to transmit second-stage output optical beams with the first and second center wavelengths, respectively. Each second-stage MZI is configured in cross-state condition.

Abstract: Disclosed are edge couplers having a high coupling efficiency and low polarization dependent loss, and methods of making the edge couplers. In one embodiment, a semiconductor device for optical coupling is disclosed. The semiconductor device includes: a substrate; an optical waveguide over the substrate; and a plurality of layers over the optical waveguide. The plurality of layers includes a plurality of coupling pillars disposed at an edge of the semiconductor device. The plurality of coupling pillars form an edge coupler configured for optically coupling the optical waveguide to an optical fiber placed at the edge of the semiconductor device.

Abstract: A silicon photonic integrated circuit is provided, which includes a first optical power splitter, a second optical power splitter, a first grating coupler and a second grating coupler. The first optical power splitter has an input, a first output and a second output, in which the input is configured to receive an inputted beam, and the first output is configured to output a returned beam. The second optical power splitter has an input, a first output and a second output, in which the input is coupled to the second output of the first optical power splitter. The first and second grating couplers are respectively coupled to the first and second outputs of the second optical power splitter, and are configured to optically couple two opposite ends of a fiber coil, respectively.

Abstract: A silicon photonic integrated circuit is provided, which includes a first optical power splitter, a second optical power splitter, a first grating coupler and a second grating coupler. The first optical power splitter has an input, a first output and a second output, in which the input is configured to receive an inputted beam, and the first output is configured to output a returned beam. The second optical power splitter has an input, a first output and a second output, in which the input is coupled to the second output of the first optical power splitter. The first and second grating couplers are respectively coupled to the first and second outputs of the second optical power splitter, and are configured to optically couple two opposite ends of a fiber coil, respectively.

Abstract: A distributed feedback (DFB) semiconductor laser device includes an active layer, a first grating layer and a second grating. The first grating layer has a first grating structure with a first grating period. The second grating layer has a second grating structure with a second grating period substantially different from the first grating period. The active layer, the first grating layer and the second grating layer are vertically stacked, and the equivalent grating period of the DFB semiconductor laser device is (2×P1×P2)/(P1+P2), where P1 and P2 respectively represent the first grating period and the second grating period.

Abstract: A distributed feedback (DFB) semiconductor laser device includes an active layer, a first grating layer and a second grating. The first grating layer has a first grating structure with a first grating period. The second grating layer has a second grating structure with a second grating period substantially different from the first grating period. The active layer, the first grating layer and the second grating layer are vertically stacked, and the equivalent grating period of the DFB semiconductor laser device is (2×P1×P2)/(P1+P2), where P1 and P2 respectively represent the first grating period and the second grating period.

Abstract: A laser interference lithography system with flat-top intensity profile comprises a laser source for emitting a coherent laser beam, a first beam expander for adjusting the coherent laser beam size, a refractive beam shaper for converting a Gaussian intensity profile inherent to the coherent laser beam into a flat-top one and outputting a first collimated laser beam, a second beam expander for receiving the first collimated laser beam and outputting a second collimated laser beam, a sample holder for holding a substrate, and at least one reflector for reflecting the second collimated laser beam to generate a third collimated laser beam. The second and third collimated laser beams are transmitted to the substrate at a predetermined angle to create an interference pattern exposed onto the substrate.

Abstract: An interference lithography device is provided with a laser source for providing a laser beam; a base thereon having a beam splitter for dividing the laser beam into a first beam portion and a second beam portion, a beam expander, a first set of reflectors, and a second set of reflectors; a set of lower reflectors; and a sample carrying stage for holding a substrate. The first beam portion and the second beam portion are respectively reflected from the second set of reflectors and then respectively reflected by the set of lower reflectors to form an interference pattern on the substrate.

Abstract: A laser interference lithography system with flat-top intensity profile comprises a laser source for emitting a coherent laser beam, a first beam expander for adjusting the coherent laser beam size, a refractive beam shaper for converting a Gaussian intensity profile inherent to the coherent laser beam into a flat-top one and outputting a first collimated laser beam, a second beam expander for receiving the first collimated laser beam and outputting a second collimated laser beam, a sample holder for holding a substrate, and at least one reflector for reflecting the second collimated laser beam to generate a third collimated laser beam. The second and third collimated laser beams are transmitted to the substrate at a predetermined angle to create an interference pattern exposed onto the substrate.

Abstract: An interference lithography device is provided with a laser source for providing a laser beam; a base thereon having a beam splitter for dividing the laser beam into a first beam portion and a second beam portion, a beam expander, a first set of reflectors, and a second set of reflectors; a set of lower reflectors; and a sample carrying stage for holding a substrate. The first beam portion and the second beam portion are respectively reflected from the second set of reflectors and then respectively reflected by the set of lower reflectors to form an interference pattern on the substrate.

Abstract: A method for larger-area fabrication of uniform silicon nanowire arrays is disclosed. The method includes forming a metal layer with a predetermined thickness on a substrate whose surface has a silicon material by a coating process, the metal layer selected from the group consisting of Ag, Au and Pt; and performing a metal-induced chemical etching for the silicon material by using an etching solution. Accordingly, a drawback that Ag nanoparticles are utilized to perform the metal-induced chemical etching in prior art is solved.

Abstract: A method for etching high-aspect-ratio features is disclosed. The method is applicable in forming a nanoscale deep trench having a smooth and angle-adjustable sidewall. The method includes: forming a patterned photoresist layer on a surface of a silicon substrate for exposing a part of the silicon substrate; and supplying a process gas simultaneously containing sulfur hexafluoride (SF6) and fluorinated carbon composition into a chamber in which the substrate in positioned for carrying out a deep reactive ion etching operation to etch the part of the silicon substrate for forming the deep trench. The method forms a nanoscale deep trench with a high silicon-to-photoresist etching selectivity.