USRE36710E - Integrated tunable optical filter - Google Patents

Integrated tunable optical filter Download PDF

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Publication number
USRE36710E
USRE36710E US09/118,474 US11847498A USRE36710E US RE36710 E USRE36710 E US RE36710E US 11847498 A US11847498 A US 11847498A US RE36710 E USRE36710 E US RE36710E
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United States
Prior art keywords
section
reflection
period
optical filter
wavelength
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Expired - Fee Related
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US09/118,474
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English (en)
Inventor
Roel Baets
Jan Willems
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Interuniversitair Microelektronica Centrum vzw IMEC
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Interuniversitair Microelektronica Centrum vzw IMEC
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Priority claimed from US08/635,057 external-priority patent/US5621828A/en
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    • G—PHYSICS
    • G02—OPTICS
    • 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
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G02F1/31—Digital deflection, i.e. optical switching
    • G02F1/313—Digital deflection, i.e. optical switching in an optical waveguide structure
    • G02F1/3132—Digital deflection, i.e. optical switching in an optical waveguide structure of directional coupler type
    • G02F1/3133—Digital deflection, i.e. optical switching in an optical waveguide structure of directional coupler type the optical waveguides being made of semiconducting materials
    • G—PHYSICS
    • G02—OPTICS
    • 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
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/30—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 grating
    • G02F2201/307—Reflective grating, i.e. Bragg grating
    • G—PHYSICS
    • G02—OPTICS
    • 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
    • G02F2203/00—Function characteristic
    • G02F2203/05—Function characteristic wavelength dependent
    • G02F2203/055—Function characteristic wavelength dependent wavelength filtering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/1028—Coupling to elements in the cavity, e.g. coupling to waveguides adjacent the active region, e.g. forward coupled [DFC] structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/1028—Coupling to elements in the cavity, e.g. coupling to waveguides adjacent the active region, e.g. forward coupled [DFC] structures
    • H01S5/1032—Coupling to elements comprising an optical axis that is not aligned with the optical axis of the active region
    • H01S5/1035—Forward coupled structures [DFC]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/12—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
    • H01S5/1206—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers having a non constant or multiplicity of periods
    • H01S5/1209—Sampled grating

Definitions

  • the invention relates to an integrated broadly tunable optical filter designed, in particular, for advanced WDM (Wavelength Division Multiplexing) applications as well as for use in spectroscopic testing of various optical components.
  • WDM Widelength Division Multiplexing
  • tunable optical filters are key components in optical communication systems. Two objectives dominate with such filters. The aims, on the one hand, are a broad tunable range and, on the other hand, high spectral selectivity. The planar integrated structures known hitherto, however, permit only one of these objectives at a time to be met.
  • a conventional filter structure known as co-directional coupler structure, is described in "Broadly tunable InGaAsP/InP buried rib waveguide vertical coupler filter" (R. C. Alferness, L. L. Buhl, U. Koren, B. I. Miller, M. G. Young, T. L. Koch, G. A. Burrus, G. Raybon), Appl. Phys. Lett. 60(8), 24 Feb. 1992.
  • This conventional structure consists of two asymmetrical waveguides having different effective refractive indices. The optical signal launched into the uppermost waveguide is launched into the lowermost waveguide and selectively reflected towards the uppermost waveguide. If the parameters of the waveguides are chosen carefully, a structure of this type can act as a selective filter.
  • a semiconductor optical structure which can provide high selectivity.
  • This conventional structure makes use of a waveguide having a grating grown thereon, that grating of which is periodically omitted.
  • a structure of this type has already been used in a tunable laser (V. Jayaraman, D. A. Cohen, L. A. Coldten, "Demonstration of broadband tunability in a semiconductor laser using sampled gratings", Appl. Phys. Lett 60(19), 11 May 1992). Nevertheless, a structure of this type has hitherto not been used in a filter structure.
  • This conventional structure provides a comb-shaped reflection spectrum.
  • the parameters thereof are the spacing between the peaks, the spectral bandwidth of the envelope of the comb spectrum, the peak maximums and the bandwidth of a reflection peak. The latter is probably the most important parameter, because it affects the selectivity of the structure. Most unfortunately, this parameter too limits the tuning range of the structure.
  • the object of the present invention is to present an optical filter structure which provides, at the same time, a large tuning range and high spectral selectivity in a compact integrated appliance.
  • the present invention makes provision for an integrated optical filter which comprises a semiconductor substrate having a common electrode on a first side thereof, the substrate comprising a first waveguide on which a grating is grown, said grating comprising a first part having a large period and a second part having a small period, from which said grating is periodically omitted.
  • a second waveguide extends in such a way that there is formed, in a first section of the substrate, a codirectional coupler section. Said second waveguide is covered by a semiconductor part whose topside carries a second electrode.
  • a third electrode Provided on the topside of the substrate at the top of the second grating section there is a third electrode.
  • the refractive indices of both waveguides in the first section are controlled by current injection along said second electrode.
  • the refractive index of the waveguide in the second section is controlled by current injection along said third electrode.
  • FIG. 1 diagrammatically represents a cross section of the structure according to the invention
  • FIGS. 2 to 6 inclusive represent curves, by way of example, which illustrate the operation of the filter structure of FIG. 1.
  • FIG. 1 shows an optical filter structure according to the invention.
  • the integrated filter structure mainly comprises substrate 1 made of semiconductor material, for example InP, in which two sections 2 and 3 are formed. On the substrate a number of layers are grown from semiconductor material, for example InGaAsP, which form the lowermost waveguide 4 having a grating 40 grown thereon.
  • Said grating 40 is grown so as to have two different geometrical structures, namely a first rib-shaped structure 41 having a long period in said first section 2, and a second periodically broken sawtooth-shaped or stripe-shaped structure 42 in said second section 3.
  • the last mentioned sawtooth-shaped structure 42 is formed so as to have short-period striped regions 43 and alternating non-striped regions 44.
  • Typical values for the period of the rib-shaped structure range between 10 and 50 ⁇ m, inclusive. Typical values for the period of the sawtooth-shaped structure are below 1 ⁇ m.
  • an uppermost waveguide 5 extends in such a way that there is formed, in the first second 2 of the substrate, a codirectional coupler section.
  • a first electrode 6 On the topside of the first section 2 there is provided a first electrode 6, by means of which current injection can be coupled in into said first section.
  • a second electrode 7 On the topside of the second section 3, too, a second electrode 7 is provided by means of which current injection can be coupled in into said second section.
  • a common back electrode 8 is provided on the underside of the substrate.
  • An appliance according to the invention works as follows.
  • An optical signal is passed into the uppermost waveguide 5, and at a certain wavelength ⁇ , 100% of the optical power is coupled across to the lowermost waveguide 4.
  • the spectral bandwidth of the codirectional coupler in section 2 is determined by the length L codir of said section 2, the period of the rib-shaped structure 41 and the effective refractive indices n 2 , and n b of the two waveguides 5 and 4, respectively, according to the following relationship: ##EQU1##
  • Said coupled wavelength can be altered by varying the refractive indices n a and n b based on current injection by applying a voltage between electrodes 6 and 8.
  • FIG. 2 represents an example of a filter response A of a codirectional coupler
  • FIG. 3 represents the same filter response A', but shifted in wavelength by current injection. It should be noted that the filter response in section 2 has a low selectivity.
  • the optical signal which was coupled to the lowermost waveguide 4 ends up in the broken sawtooth-shaped structure 42.
  • the reflection spectrum of said structure is comb-shaped as shown by B in FIG. 4, together with the filter response of the first section.
  • the reflection peaks of the comb spectrum have a high selectivity.
  • the selectivity is mainly determined by the number of periods in the broken structure 42 and the coupling strength of that structure.
  • the reflection peaks of the comb spectrum B can be changed slightly by current injection in said section when a voltage is applied between electrodes 7 and 8.
  • the Comb spectrum is slightly shifted in wavelength as shown by B' in FIG. 5.
  • the wavelength of one of the reflection peaks corresponds to the central coupling wavelength of the first section 2.
  • the parameters of the two sections 2 and 3 cannot be chosen totally independently of one another, but must satisfy at least the following condition.
  • This condition establishes a relationship between the spectral bandwidth of the codirectional coupler and the spacing between the peaks in the comb spectrum of section 3. This bandwidth must be smaller than the spacing between the peaks: ##EQU2## where ⁇ 3db is the spectral bandwidth of the codirectional coupler: ##EQU3## where: ⁇ is the wavelength
  • ⁇ is the period of the rib-shaped structure in the first section
  • L codir is the length of the first section
  • n a , n b are the effective refractive indices of the two waveguides in the first section
  • L 1 is the length of the sawtooth-shaped structure grating in one period of the second section
  • L 2 is the length of the non-striped portion of the grating structure in one period of the second section
  • n is the effective refractive index of the waveguide in the second section.
  • the tuning range is determined by both sections and is no greater than the maximum of two variables, namely ⁇ 1 , the tuning range of the codirectional structure, and ⁇ 2 , the spectral bandwidth of the envelope of the comb spectrum at the second section 3. ##EQU4##

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Integrated Circuits (AREA)
  • Semiconductor Lasers (AREA)
  • Lasers (AREA)
US09/118,474 1992-09-14 1998-07-17 Integrated tunable optical filter Expired - Fee Related USRE36710E (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US09/118,474 USRE36710E (en) 1992-09-14 1998-07-17 Integrated tunable optical filter

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
BE09200838 1992-09-24
BE9200838A BE1006207A3 (nl) 1992-09-24 1992-09-24 Geintegreerd afstembaar optisch filter.
US08/635,057 US5621828A (en) 1992-09-24 1996-04-19 Integrated tunable optical filter
US09/118,474 USRE36710E (en) 1992-09-14 1998-07-17 Integrated tunable optical filter

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US08/635,057 Reissue US5621828A (en) 1992-09-14 1996-04-19 Integrated tunable optical filter

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USRE36710E true USRE36710E (en) 2000-05-23

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Country Status (7)

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US (1) USRE36710E (de)
EP (1) EP0613571B1 (de)
JP (1) JP3185930B2 (de)
AT (1) ATE169127T1 (de)
BE (1) BE1006207A3 (de)
DE (1) DE69320022T2 (de)
WO (1) WO1994007178A1 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030128724A1 (en) * 2001-09-10 2003-07-10 Imec Vzw Widely tunable twin guide laser structure
US6665474B2 (en) 2001-02-22 2003-12-16 Altitun Ab Method of improving selectivity in a tunable waveguide filter
US6904065B2 (en) 2001-02-22 2005-06-07 Adc Telecommunications, Inc. Method and apparatus for compensating losses in a tunable laser filter
US7023886B2 (en) 2001-11-08 2006-04-04 Intel Corporation Wavelength tunable optical components

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6674929B2 (en) * 2001-06-01 2004-01-06 Lightcross, Inc. Tunable optical filter
US6810168B1 (en) 2002-05-30 2004-10-26 Kotura, Inc. Tunable add/drop node
US20220171105A1 (en) * 2020-09-11 2022-06-02 Board Of Regents, The University Of Texas System Resonant filters having simultaneously tuned central wavelengths and sidebands

Citations (9)

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US4743087A (en) * 1984-06-07 1988-05-10 Kokusai Denshin Denwa Kabushiki Kaisha Optical external modulation semiconductor element
US4976513A (en) * 1987-11-11 1990-12-11 Nec Corporation Tunable wavelength filter
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US5220573A (en) * 1989-03-10 1993-06-15 Canon Kabushiki Kaisha Optical apparatus using wavelength selective photocoupler
US5253314A (en) * 1992-01-31 1993-10-12 At&T Bell Laboratories Tunable optical waveguide coupler
US5325392A (en) * 1992-03-06 1994-06-28 Nippon Telegraph And Telephone Corporation Distributed reflector and wavelength-tunable semiconductor laser
US5416866A (en) * 1992-08-26 1995-05-16 Telefonaktiebolaget L M Ericsson Optical waveguide/grating device for filtering optical wavelengths

Patent Citations (9)

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US4743087A (en) * 1984-06-07 1988-05-10 Kokusai Denshin Denwa Kabushiki Kaisha Optical external modulation semiconductor element
US4976513A (en) * 1987-11-11 1990-12-11 Nec Corporation Tunable wavelength filter
US5147825A (en) * 1988-08-26 1992-09-15 Bell Telephone Laboratories, Inc. Photonic-integrated-circuit fabrication process
US5220573A (en) * 1989-03-10 1993-06-15 Canon Kabushiki Kaisha Optical apparatus using wavelength selective photocoupler
JPH0479287A (ja) * 1990-07-20 1992-03-12 Canon Inc 波長可変半導体レーザ
US5189714A (en) * 1990-09-28 1993-02-23 Oki Electric Industry Co., Ltd. Optical wavelength filter device
US5253314A (en) * 1992-01-31 1993-10-12 At&T Bell Laboratories Tunable optical waveguide coupler
US5325392A (en) * 1992-03-06 1994-06-28 Nippon Telegraph And Telephone Corporation Distributed reflector and wavelength-tunable semiconductor laser
US5416866A (en) * 1992-08-26 1995-05-16 Telefonaktiebolaget L M Ericsson Optical waveguide/grating device for filtering optical wavelengths

Non-Patent Citations (15)

* Cited by examiner, † Cited by third party
Title
Alferness et al, "Broadly tunable InGaAsP/InP buried rib waveguide vertical coupler filter", Appl. Phys. Lett. 60(8), pp. 980-982, Feb. 1992.
Alferness et al, Broadly tunable InGaAsP/InP buried rib waveguide vertical coupler filter , Appl. Phys. Lett. 60(8), pp. 980 982, Feb. 1992. *
Hirata et al, "Monolithic resonant optical reflector laser diodes", Electronics Letters, vol. 27, No. 22, pp. 2050-2051, Oct. 1991.
Hirata et al, Monolithic resonant optical reflector laser diodes , Electronics Letters, vol. 27, No. 22, pp. 2050 2051, Oct. 1991. *
IEEE Photonics Technology Letters, vol. 5, No. 7, Jul. 1993, M. Oberg et al, "74 mm wavelength tuning range of an InGaAsP/InP vertical grating assisted codirectionsl coupler laser . . . " (p. 735).
IEEE Photonics Technology Letters, vol. 5, No. 7, Jul. 1993, M. Oberg et al, 74 mm wavelength tuning range of an InGaAsP/InP vertical grating assisted codirectionsl coupler laser . . . (p. 735). *
Jayarman et al. "Demonstration of broadband tunability in a semiconductor laser using sampled gratings", Appl. Phys. Lett. 60(19), pp.2321-2323 May 1992.
Jayarman et al. Demonstration of broadband tunability in a semiconductor laser using sampled gratings , Appl. Phys. Lett. 60(19), pp.2321 2323 May 1992. *
Olsson et al, "Performance characteristics of a 1.5 um single frequency semiconductor laser with an external waveguide Bragg reflector", IEEE J. of Quantum Elec., vol. 24, No. 2, pp. 143-147, Feb. 1988.
Olsson et al, Performance characteristics of a 1.5 um single frequency semiconductor laser with an external waveguide Bragg reflector , IEEE J. of Quantum Elec., vol. 24, No. 2, pp. 143 147, Feb. 1988. *
Willems et al, "Novel widely tunable integrated optical filter with high spectral selectivity", 18th European Conference on Optical Communication Oct. 1992.
Willems et al, Novel widely tunable integrated optical filter with high spectral selectivity , 18th European Conference on Optical Communication Oct. 1992. *
Willens et al, Novel widley tunable integrated optical filter with high spectral selectivity, 18th European Conference on Optical Communication, Oct. 1992. *
Yayaraman et al, "Demonstration of broadband tunability in a semiconductor laser using sampled gratings", Appl. Phys. Lett. 60(19), pp. 2321-2323, May 1992.
Yayaraman et al, Demonstration of broadband tunability in a semiconductor laser using sampled gratings , Appl. Phys. Lett. 60(19), pp. 2321 2323, May 1992. *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6665474B2 (en) 2001-02-22 2003-12-16 Altitun Ab Method of improving selectivity in a tunable waveguide filter
US6904065B2 (en) 2001-02-22 2005-06-07 Adc Telecommunications, Inc. Method and apparatus for compensating losses in a tunable laser filter
US20030128724A1 (en) * 2001-09-10 2003-07-10 Imec Vzw Widely tunable twin guide laser structure
US7653093B2 (en) * 2001-09-10 2010-01-26 Imec Widely tunable twin guide laser structure
US7023886B2 (en) 2001-11-08 2006-04-04 Intel Corporation Wavelength tunable optical components

Also Published As

Publication number Publication date
BE1006207A3 (nl) 1994-06-07
DE69320022T2 (de) 1999-03-25
JPH07501628A (ja) 1995-02-16
ATE169127T1 (de) 1998-08-15
EP0613571B1 (de) 1998-07-29
WO1994007178A1 (en) 1994-03-31
JP3185930B2 (ja) 2001-07-11
EP0613571A1 (de) 1994-09-07
DE69320022D1 (de) 1998-09-03

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