# US 7,609,915 B2 · Apparatus and method for a waveguide-based optical polarizer/isolator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,915 B2 - Document ID: US7609915B2 - Status: Granted - Kind: B2 - Application number: 11/855,149 - Filed: 2007-09-13 - Published: 2009-01-15 - Granted: 2009-10-27 - Earliest claimed: 2006-09-13 - Inventors: Gennady Shvets - Web page: https://patentgrep.com/patent/US7609915B2 ## CPC - G02B 6/126: using polarisation effects {(G02B6/1226 takes precedence)} - G02B 6/4208: {using non-reciprocal elements or birefringent plates, i.e. quasi-isolators (optical isolators per se G02F1/093, G02F1/0955)} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract The present invention provides an apparatus for a one-way waveguide and/or a circular polarizer that includes a waveguide having a height, a width, a length and a wave propagation direction. A first wall of the waveguide has a first slanted groove. A second wall opposite the first wall of the waveguide has a second slanted groove. The first and second grooves are rotated clockwise around the wave propagation direction to approximate a helical groove. The present invention may also include a third slanted groove in a third wall adjacent to the first wall and second wall, a fourth slanted groove in a fourth wall opposite the third wall, and the first, second, third and fourth grooves are rotated clockwise around the wave propagation direction to approximate the helical groove. ## Claims ### Claim 1 An apparatus comprising: a waveguide having a height (H), a width (W), a length of at least a period (λu) and a wave propagation direction (x); a first slanted groove in a first wall of the waveguide; a second slanted groove in a second wall opposite the first wall; and wherein the slanted grooves are rotated clockwise around the wave propagation direction (x) to approximate a helical groove. ### Claim 2 (depends on 1) The apparatus as recited in claim 1, wherein the wave guide is substantially rectangular. ### Claim 3 (depends on 1) The apparatus as recited in claim 1, wherein W=H=2L and L is approximately equal to a quarter of the vacuum wavelength. ### Claim 4 (depends on 3) The apparatus as recited in claim 3, wherein the period (λu) comprises an integer multiple of L. ### Claim 5 (depends on 1) The apparatus as recited in claim 1, wherein each slanted groove comprises a channel, a cut, an incision or an indentation that is substantially rectangular having a width (w) and a height (h). ### Claim 6 (depends on 5) The apparatus as recited in claim 5, wherein w=h or w≠h. ### Claim 7 (depends on 1) The apparatus as recited in claim 1, wherein the first and second slanted grooves introduce chirality which transmits one circular polarization of light and reflects the other circular polarization of light. ### Claim 8 (depends on 1) The apparatus as recited in claim 1, wherein the first and second slanted grooves produce a chiral bandgap having a lower edge (ω1) and an upper edge (ω2). ### Claim 9 (depends on 1) The apparatus as recited in claim 1, further comprising a metal coating on each wall. ### Claim 10 (depends on 1) The apparatus as recited in claim 1, wherein the waveguide comprises a silicon-based waveguide. ### Claim 11 (depends on 1) The apparatus as recited in claim 1, further comprising: a third slanted groove in a third wall adjacent to the first wall and second wall; a fourth slanted groove in a fourth wall opposite the third wall; and wherein the first, second, third and fourth grooves are rotated clockwise around the wave propagation direction (x) to approximate a helical groove and introduce chirality which transmits one circular polarization of light and reflects the other circular polarization of light. ### Claim 12 An apparatus comprising: a waveguide having a height (H), a width (W), a length of at least a period (λu) and a wave propagation direction (x), and wherein W=H=2L, the period (λu) comprises an integer multiple of L, and L is approximately equal to a quarter of the vacuum wavelength; a first slanted groove in a first wall of the waveguide; a second slanted groove in a second wall opposite the first wall; and each slanted groove comprises a channel, a cut, an incision or an indentation that is substantially rectangular having a width (w) and a height (h), and wherein the first and second grooves are rotated clockwise around the wave propagation direction (x) to approximate a helical groove. ### Claim 13 (depends on 12) The apparatus as recited in claim 12, further comprising: a third slanted groove in a third wall adjacent to the first wall and second wall; a fourth slanted groove in a fourth wall opposite the third wall; and wherein the first, second, third and fourth grooves are rotated clockwise around the wave propagation direction (x) to approximate a helical groove and introduce chirality which transmits one circular polarization of light and reflects the other circular polarization of light. ### Claim 14 (depends on 12) The apparatus as recited in claim 12, further comprising a metal coating on each wall. ### Claim 15 (depends on 12) The apparatus as recited in claim 12, wherein the waveguide comprises a silicon-based waveguide. ### Claim 16 A method for producing a one-way waveguide and/or a circular polarizer comprising the steps of: providing a waveguide having a height (H), a width (W), a length of at least a period (λu) and a wave propagation direction (x); and creating a first slanted groove in a first wall of the waveguide and a second slanted groove in a second wall opposite the first wall such that the first and second grooves are rotated clockwise around the wave propagation direction (x) to approximate a helical groove. ### Claim 17 (depends on 16) The method as recited in claim 16, wherein: W=H=2L; the period (λu) comprises an integer multiple of L; L is approximately equal to a quarter of the vacuum wavelength; and each slanted groove has a width (w), a height (h), and w=h or w≠h. ### Claim 18 (depends on 16) The method as recited in claim 16, further comprising the step of coating each wall with a metal. ### Claim 19 (depends on 16) The method as recited in claim 16, wherein the waveguide comprises a silicon-based waveguide. ### Claim 20 (depends on 16) The method as recited in claim 16, further comprising the step of creating a third slanted groove in a third wall adjacent to the first wall and second wall and a fourth slanted groove in a fourth wall opposite the third wall such that the first, second, third and fourth grooves are rotated clockwise around the wave propagation direction (x) to approximate the helical groove. ### Claim 21 (depends on 16) The method as recited in claim 16, wherein each slanted groove comprises a channel, a cut, an incision or an indentation that is substantially rectangular having a width (w) and a height (h).