# US 8,542,425 B2 · Wavelength tunable light source > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,425 B2 - Document ID: US8542425B2 - Status: Granted - Kind: B2 - Application number: 12/971,233 - Filed: 2010-12-17 - Published: 2011-06-23 - Granted: 2013-09-24 - Earliest claimed: 2009-12-18 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Seung-Hyun Cho; Jong Hoon Lee; Eun Gu Lee; Jie Hyun Lee; Han-Hyub Lee; Eui Suk Jung; Sang Soo Lee - Inventors: Seung-Hyun Cho; Jong Hoon Lee; Eun Gu Lee; Jie Hyun Lee; Han-Hyub Lee; Eui Suk Jung; Sang Soo Lee - Web page: https://patentgrep.com/patent/US8542425B2 ## CPC - G02B 6/4215: {the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers (G02B6/4246 takes precedence)} - G02F 1/133608: {including particular frames or supporting means} - H01S 5/02438: {Characterized by cooling of elements other than the laser chip, e.g. an optical element being part of an external cavity or a collimating lens} - H01S 5/141: {using a wavelength selective device, e.g. a grating or etalon (H01S5/146 takes precedence)} - H01S 5/0071: {for beam steering, e.g. using a mirror outside the cavity to change the beam direction} - H01S 5/0085: {for modulating the output, i.e. the laser beam is modulated outside the laser cavity} - H01S 5/02212: Can-type, e.g. TO-CAN housings with emission along or parallel to symmetry axis - H01S 5/02251: using optical fibres - H01S 5/02325: Mechanically integrated components on mount members or optical micro-benches - H01S 5/02415: {by using a thermo-electric cooler [TEC], e.g. Peltier element} - H01S 5/0265: {Intensity modulators (intra-cavity modulators H01S5/0625)} - H01S 5/0287: {Facet reflectivity} - H01S 5/06226: {Modulation at ultra-high frequencies} - H01S 5/06251: {Amplitude modulation} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL ## Abstract A wavelength tunable light source includes: an optical gain medium generating light; a wavelength tunable filter positioned on a optical path and transmitting or reflecting only a predetermined wavelength generated from and injected into the optical gain medium; a first housing where the optical gain medium and the wavelength tunable filter are mounted; and an optical fiber block providing the optical wave having the predetermined wavelength come from the wavelength tunable filter, wherein the wavelength tunable filter comprised of a dielectric thin-film filter formed by alternately stacking a first dielectric thin film layer and a second dielectric thin film layer having different refractive index. ## Claims ### Claim 1 A wavelength tunable light source, comprising: an optical gain medium for generating broadband light, the optical gain medium being made of a gain material, such that no resonance of light is created therein when the broadband light is generated; a wavelength tunable filter positioned on an optical path of the broadband light and transmitting or reflecting a portion of the broadband light injected thereinto that has only a predetermined wavelength; a first housing where the optical gain medium and the wavelength tunable filter are mounted; and an optical fiber for outputting the portion of the broadband light having the predetermined wavelength from the wavelength tunable filter, wherein the wavelength tunable filter includes a dielectric thin-film filter formed by alternately stacking a first dielectric thin film layer and a second dielectric thin film layer that have different refractive indices. ### Claim 2 (depends on 1) The wavelength tunable light source of claim 1, wherein: the first dielectric thin film layer and the second dielectric thin film layer have different thermooptic coefficients. ### Claim 3 (depends on 1) The wavelength tunable light source of claim 1, wherein: the first dielectric thin film is made of an amorphous silicon based material which is hydrogenated and the second dielectric thin film is made of a silicon nitroxide based material or a silicon nitride based material. ### Claim 4 (depends on 1) The wavelength tunable light source of claim 1, wherein: the wavelength tunable filter further includes a reflection plate, and the reflection plate reflects the optical wave transmitted through the dielectric thin-film filter from the optical gain medium. ### Claim 5 (depends on 4) The wavelength tunable light source of claim 4, wherein the dielectric thin-film filter is placed with a typical angle along the incident direction of the broadband light injected into the wavelength tunable filter. ### Claim 6 (depends on 4) The wavelength tunable light source of claim 4, wherein the reflection plate is a reflective thin film layer. ### Claim 7 (depends on 1) The wavelength tunable light source of claim 1, further comprising a lens for optical coupling that is supported by the first housing, wherein the lens is positioned on an optical path of the portion of the broadband light that is transmitted through the wavelength tunable filter or reflected from the wavelength tunable filter to the optical fiber. ### Claim 8 (depends on 1) The wavelength tunable light source of claim 1, further comprising: a thermistor and a thermo-electric cooler that are mounted on the first housing coincidently, wherein the optical gain medium, the wavelength tunable filter, and the thermistor are placed on the thermo-electric cooler. ### Claim 9 (depends on 1) The wavelength tunable light source of claim 1, further comprising: an optical wave distributor with a mirror mounted in the first housing and changing an direction of the portion of the broadband light having a predetermined wavelength transmitted through the wavelength tunable filter or reflected from the wavelength tunable filter; and an optical detector mounted in the first housing and monitoring performance of the wavelength tunable light source by detecting partial optical light refracted by the optical wave distributor with the mirror. ### Claim 10 (depends on 1) The wavelength tunable light source of claim 1, further comprising an external modulator disposed between the first housing and the optical fiber. ### Claim 11 (depends on 10) The wavelength tunable light source of claim 10, wherein: the external modulator includes an electroabsorption modulator. ### Claim 12 (depends on 11) The wavelength tunable light source of claim 11, wherein: the external modulator is formed by integrating the electroabsorption modulator and a reflective semiconductor optical amplifier. ### Claim 13 (depends on 10) The wavelength tunable light source of claim 10, further comprising: a second housing where the external modulator is mounted; and an optical fiber ferrule where the optical fiber is mounted. ### Claim 14 (depends on 13) The wavelength tunable light source of claim 13, wherein: the first housing is formed by a transistor outlined package and the second housing is formed by a box-type package. ### Claim 15 (depends on 10) The wavelength tunable light source of claim 10, further comprising: a first lens for coupling the optical gain mediumn and the wavelength tunable filter and the external modulator; and a second optical coupling lens for optically coupling the external modulator and the optical fiber. ### Claim 16 A wavelength tunable light source, comprising: an optical gain medium generating broadband light; a wavelength tunable filter positioned on an optical path of the broadband light and transmitting or reflecting a portion of the broadband light injected thereinto that has only a predetermined wavelength; a first housing, the optical gain medium and the wavelength tunable filter being mounted therein; and an optical fiber for outputting, from the wavelength tunable filter, the portion of the broadband light having the predetermined wavelength, wherein the wavelength tunable filter includes a dielectric thin-film filter that has alternately stacked first and second dielectric thin film layers of different refractive indices, and the optical gain medium is comprised of a reflective semiconductor optical amplifier or a semiconductor laser diode, and the reflectance of a front emission surface is 0.1% or less and the reflectance of a rear emission surface is 90% or more. ### Claim 17 (depends on 16) The wavelength tunable light source of claim 16, further comprising an electroabsorption modulator for high speed modulation that is integrated with the reflective semiconductor optical amplifier or the semiconductor laser diode.