# US 7,612,935 B2 · Third-order optical autocorrelator for time-domain operation at the telecommunication wavelengths

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- Number: US 7,612,935 B2
- Document ID: US7612935B2
- Status: Granted
- Kind: B2
- Application number: 10/557,809
- Filed: 2003-12-19
- Published: 2007-09-27
- Granted: 2009-11-03
- Earliest claimed: 2003-05-30
- Assignees: Arizona Board of Regents on Behalf of the University of Arizona
- Inventors: Gabriel Ramos-Ortiz; Myoungsik Cha; Seth R. Marder; Bernard Kippelen
- Web page: https://patentgrep.com/patent/US7612935B2

## CPC

- G02F 1/3532: {Arrangements of plural nonlinear devices for generating multi-colour light beams, e.g. arrangements of SHG, SFG, OPO devices for generating RGB light beams}
- G02F 1/353: {Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams}
- G02F 1/3614: {Heterocycles having S as heteroatom}
- G02F 1/3615: {containing polymers}
- G02F 1/354: {Third or higher harmonic generation}
- 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

## Abstract

A device and method for producing a third harmonic signal from an optical pulse of wavelength k. In the device and method, an optical pulse at a wavelength k is incident on a material including at least one molecule having a formula D—U—A, where D is an electron donor group, A is an electron acceptor group, and Π is a conjugated structure having it bonds that connect D to A. The molecule exhibits a strong absorption band centered at a wavelengthko and a weakly absorbing region centered at a wavelength k, which is less than Xo. A wavelength k/2 has a value of about Xo, and a wavelength k/3 has a value of about X1. A third harmonic signal at k/3 is generated. From a measured third harmonic signal as a function of a time delay for separate optical pulses entering the material, at least one of a pulse width and a pulse shape of the optical pulse can be extracted. From a spectrally resolved third harmonic signal, a phase of the optical pulse can be extracted.

## Claims

### Claim 1

A method for producing a third harmonic signal from a laser light of wavelength λ, comprising:
irradiating said laser light on a material including a molecule having a formula D-Π-A, where D is an electron donor group, A is an electron acceptor group, and Π is a conjugated structure having π bonds that connect the D donor group to the A acceptor group, said molecule exhibiting an absorption band at a wavelength λ0 and exhibiting a weakly absorbing region as compared to the absorption band at λ0 at a wavelength λ1, such that λ1<λ0;
adjusting the wavelength λ of said laser light such that λ/2 has a value of about λ0 and λ/3 has a value of about λ1, thereby generating said third harmonic signal.

### Claim 2 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
interacting two time delayed optical pulses of the laser light in the material to thereby generate said third harmonic signal.

### Claim 3 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
dividing the laser light into a first part and a second part;
time delaying the first part relative to the second part;
recombining the first and second parts; and
focusing the time-delayed and recombined parts into the material to thereby generate said third harmonic signal.

### Claim 4 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material having a molecule defined by the formula:

### Claim 5 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material having a molecule defined by the formula:

### Claim 6 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating a polymer of said molecule.

### Claim 7 (depends on 6)

The method of claim 6, wherein said irradiating comprises:
irradiating an amorphous glass of said polymer.

### Claim 8 (depends on 6)

The method of claim 6, wherein said irradiating comprises:
irradiating said material in which said molecule is attached as a side-chain to said polymer.

### Claim 9 (depends on 6)

The method of claim 6, wherein said irradiating comprises:
irradiating said material in which said molecule is in a main chain of said polymer.

### Claim 10 (depends on 6)

The method of claim 6, wherein said irradiating comprises:
irradiating said material in which said molecule is incorporated in a dendrimer.

### Claim 11 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating an optically transparent polymer at the wavelength λ of the laser.

### Claim 12 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material in which said molecule includes a chromophore.

### Claim 13 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material in which said weakly absorbing region has an absorption coefficient less than 10,000 cm−1.

### Claim 14 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material in which a polymer of said molecule is transparent at 1550 nm, absorbing at 775 nm, and weakly absorbing at 517 nm as compared to 775 mn.

### Claim 15 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material having said donor group comprising at least one of atoms or molecular groups having a low ionization potential.

### Claim 16 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material having said donor group comprising at least one of I, Br, Cl, F, OC(O)R, SH, OH, SR, OR, NHC(O)R, NH2, NHR, NR2, S−, and O−,
where R is any one of an alkyl, aryl, and carbazole group.

### Claim 17 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material having said acceptor group comprising at least one of atoms or molecular groups having a high electron affinity.

### Claim 18 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material having said acceptor group comprising at least one of:
C(O)NR2, C(O)NHR, C(O)NH2, C(O)OR, C(O)OH, C(O)R, C(O)H, CN, S(O2)R, and NO2,
where R is any one of an alkyl, aryl, and carbazole group.

### Claim 19 (depends on 1)

The method of claim 1, wherein said irradiating comprises:
irradiating said material having said acceptor group comprising at least one of:
where * indicates the point of attachment of the accept to a π bridge via a single bond.

### Claim 20

A method for measuring an optical pulse, comprising:
receiving the optical pulse of a wavelength of λ from a source;
dividing the optical pulse into two parts to produce a time delay between each part;
combining the two parts of the optical pulse in a material including a molecule having a formula D-Π-A, where D is an electron donor group, A is an electron acceptor group, and Π is a conjugated structure having π bonds that connect the D donor group to the A acceptor group, said molecule exhibiting an absorption band at a wavelength λ0 and exhibiting a weakly absorbing region as compared to the absorption band at λ0 at a wavelength λ1, such that λ1<λ0 that λ/2 has a value of about λ0 and that λ/3 has a value of about λ1;
measuring a third harmonic signal at λ/3 as a function of the time delay between the two parts of the optical pulse;
extracting from said third harmonic signal as a function of the time delay at least one of a pulse width and a pulse shape correlated with the optical pulse.

### Claim 21 (depends on 20)

The method of claim 20, wherein said combining comprises:
propagating the two parts of the optical pulse linearly in said material.

### Claim 22 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating said material having a molecule defined by the formula:

### Claim 23 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating said material having a molecule defined by the formula:

### Claim 24 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating a polymer of said molecule.

### Claim 25 (depends on 24)

The method of claim 24, wherein said irradiating comprises:
irradiating an amorphous glass of said polymer.

### Claim 26 (depends on 24)

The method of claim 24, wherein said irradiating comprises:
irradiating said material in which said molecule is attached as a side-chain to said polymer.

### Claim 27 (depends on 24)

The method of claim 24, wherein said irradiating comprises:
irradiating said material in which said molecule is in a main chain of said polymer.

### Claim 28 (depends on 24)

The method of claim 24, wherein said irradiating comprises:
irradiating said material in which said molecule is incorporated in a dendrimer.

### Claim 29 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating an optically transparent polymer at the wavelength λ of the optical pulse.

### Claim 30 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating said material in which said molecule includes a chromophore.

### Claim 31 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating said material in which said weakly absorbing region has an absorption coefficient less than 10,000 cm−1.

### Claim 32 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating said material in which a polymer of said molecule is transparent at 1550 nm, absorbing at 775 nm, and weakly absorbing at 517 nm as compared to 775 nm.

### Claim 33 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating said material having said donor group comprising at least one of atoms or molecular groups having a low ionization potential.

### Claim 34 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating said material having said donor group comprising at least one of I, Br, Cl, F, OC(O)R, SH, OH, SR, OR, NHC(O)R, NH2, NHR, NR2, S−, and O−,
where R is any one of an alkyl, aryl, and carbazole group.

### Claim 35 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating said material having said acceptor group comprising at least one of atoms or molecular groups having a high electron affinity.

### Claim 36 (depends on 20)

The method of claim 20, wherein said combining comprises:
irradiating said material having said acceptor group comprising at least one of C(O)NR2, C(O)NHR, C(O)NH2, C(O)OR, C(O)H, C(O)R, C(O)H, CN, S(O2)R, and NO2,
where R is any one of an alkyl, aryl, and carbazole group.

### Claim 37 (depends on 20)

The method of claim 20, wherein said irradiating comprises:
irradiating said material having said acceptor group comprising at least one of:
where * indicates the point of attachment of the accept to a π bridge via a single bond.

### Claim 38 (depends on 20)

The method of claim 20, wherein said combining comprises:
combining the two parts of the optical pulse such that said two parts have equal intensities.

### Claim 39 (depends on 20)

The method of claim 20, wherein said extracting comprises:
extracting a temporal waveform from a laser pulse.

### Claim 40 (depends on 39)

The method of claim 39, wherein said extracting comprises:
extracting said temporal waveform from a pulsed telecommunications laser.

### Claim 41 (depends on 39)

The method of claim 39, wherein said extracting comprises:
extracting said temporal waveform from ultra-fast lasers having a pulse width of less than 100 picoseconds.

### Claim 42 (depends on 20)

The method of claim 20, wherein said combining comprises:
combining the two parts of the optical pulse non-collinearly and such that said two parts are phase matched.

### Claim 43 (depends on 42)

The method of claim 42, wherein said combining comprises:
generating a plurality of third harmonic signals propagating in different directions from an incident direction of said two parts of the optical pulse;
measuring a spectrum of one of the third hannonie signals generated in said different directions as a function of the delay between the two parts of the optical pulse;
extracting from the measured spectrum as a function of the time delay a phase of the optical pulse.

### Claim 44 (depends on 20)

The device of claim 20, wherein said extracting comprises:
determining a phase of said optical pulse from a spectrally resolved third harmonic signal as a function of the time delay.

### Claim 45

A device for producing a third harmonic signal from an optical pulse of wavelength λ, comprising:
a material including a molecule, having a formula D-Π-A, where D is an electron donor group, A is an electron acceptor group, and Π is a conjugated structure having π bonds that connect the D donor group to the A acceptor group, said molecule exhibiting a strong absorption band centered at a wavelength λ0 and exhibiting a weakly absorbing region as compared to the absorption band at λ0 at a wavelength λ1 such that λ1<λ0;
a divider configured to receive the optical pulse from a source and divide the pulse into two parts to produce a time delay between each part;
a combiner configured to combine the two parts of the optical pulse having said time delay; and
an optical element configured to couple the time-delayed and combined two parts into the material to thereby generate the third harmonic signal.

### Claim 46 (depends on 45)

The device of claim 45, wherein the molecule is defined by the formula:

### Claim 47 (depends on 45)

The device of claim 45, wherein the molecule is defined by the formula

### Claim 48 (depends on 45)

The device of claim 45, wherein said material is an optically transparent polymer.

### Claim 49 (depends on 48)

The device of claim 48, wherein said polymer is in an amorphous glass.

### Claim 50 (depends on 48)

The device of claim 48, wherein said molecule is attached as a side-chain to said polymer.

### Claim 51 (depends on 48)

The device of claim 48, wherein said molecule is in a main chain of said polymer.

### Claim 52 (depends on 48)

The device of claim 48, wherein said molecule is incorporated in a dendrimer.

### Claim 53 (depends on 48)

The device of claim 48, wherein said molecule includes a chromophore.

### Claim 54 (depends on 45)

The device of claim 45, wherein said material in said weakly absorbing region has an absorption co-efficient less than 10,000 cm−1.

### Claim 55 (depends on 45)

The device of claim 45, wherein said molecule is transparent at 1550 nm, absorbing at 775 mn, and weakly absorbing at 517 nm as compared to 775 nm.

### Claim 56 (depends on 45)

The device of claim 45, wherein said material having said donor group comprises:
at least one of atoms or molecular groups having a low ionization potential.

### Claim 57 (depends on 45)

The device of claim 45, wherein said material having said donor group comprises:
at least one of I, Br, Cl, F, OC(O)R, SH, OH, SR, OR, NHC(O)R, NH2, NHR, NR2, S+, and O+, where R is any one of an alkyl, aryl, and carbazole group.

### Claim 58 (depends on 45)

The device of claim 45, wherein said material having said acceptor group comprises:
at least one of atoms or molecular groups having a high electron affinity.

### Claim 59 (depends on 45)

The device of claim 45, wherein said material having said acceptor group comprises:
at least one of C(O)NR2, C(O)NHR, C(O)NH2, C(O)OR, C(O)OH, C(O)R, C(O)H, CN, S(O2)R, and NO2, where R is any one of an alkyl, aryl, and carbazole group.

### Claim 60 (depends on 45)

The device of claim 45, wherein said irradiating comprises:
irradiating said material having said acceptor group comprising at least one of:
where * indicates the point of attachment of the accept to a π bridge via a single bond.

### Claim 61

A device for measuring an optical pulse at a wavelength λ, comprising:
a divider configured to receive the optical pulse from a source and divide the pulse into two parts to produce a time delay between each part;
a combiner configured to combine the two parts of the optical pulse having said time delay;
a material receiving said two parts of the optical pulse, said material comprising at least one molecule having a formula D-Π-A, where D is an electron donor group, A is an electron acceptor group, and Π is a conjugated structure having π bonds that connect D to A, said molecule exhibiting a strong absorption band centered at a wavelength λ0 and exhibiting a weakly absorbing region as compared to the absorption band at λ0 at a wavelength λ1, such that λ1<λ0, that λ/2 has a value of about λ0, and that λ/3 has a value of about λ1;
a detector configured to measure a third harmonic signal at λ/3 as a function of the time delay between the two parts of the optical pulse; and
an extractor configured to extract, from said third harmonic signal as a function of the time delay, at least one of a pulse width and a pulse shape correlated with the optical pulse.

### Claim 62 (depends on 61)

The device of claim 61, wherein the combiner is configured to combine said two parts of the optical pulse linearly in the material.

### Claim 63 (depends on 61)

The device of claim 61, wherein the molecule is defied by the formula:

### Claim 64 (depends on 61)

The device of claim 61, wherein the molecule is defined by the formula

### Claim 65 (depends on 61)

The device of claim 61, wherein the material comprises a polymer.

### Claim 66 (depends on 65)

The device of claim 65, wherein said polymer comprises an amorphous glass.

### Claim 67 (depends on 65)

The device of claim 65, wherein said molecule is attached as a side-chain to said polymer.

### Claim 68 (depends on 65)

The device of claim 65, wherein said molecule is in a main chain of said polymer.

### Claim 69 (depends on 65)

The device of claim 65, wherein said molecule is incorporated in a dendrimer.

### Claim 70 (depends on 61)

The device of claim 61, wherein said material comprises:
an optically transparent polymer at the wavelength λ.

### Claim 71 (depends on 61)

The device of claim 61, wherein said molecule includes a chromophore.

### Claim 72 (depends on 61)

The device of claim 61, wherein said molecule in said weakly absorbing region has an absorption coefficient less than 10,000 cm−1.

### Claim 73 (depends on 61)

The device of claim 61, wherein said molecule is transparent at 1550 nm, absorbing at 775 nm, and weakly absorbing at 517 nm as compared to 775 nm.

### Claim 74 (depends on 61)

The device of claim 61, wherein said material having said donor group comprises:
at least one of atoms or molecular groups having a low ionization potential.

### Claim 75 (depends on 61)

The device of claim 61, wherein said material having said donor group comprises:
at least one of I, Br, Cl, F, OC(O)R, SH, OH, SR, OR, NHC(O)R, NH2, NHR, NR2, S−, and O−, where R is any one of an aryl group and a carbazole group.

### Claim 76 (depends on 61)

The device of claim 61, wherein said material having said acceptor group comprises:
at least one of atoms or molecular groups having a high electron affinity.

### Claim 77 (depends on 61)

The device of claim 61, wherein said material having said acceptor group comprises:
at least one of C(O)NR2, C(O)NHR, C(O)NH2, C(O)OR, C(O)OR, C(O)OH, C(O)OH, C(O)R, C(O)H, CN, S(O2)R, and NO2,
where R is any one of an aryl group and a carbazole group.

### Claim 78 (depends on 61)

The device of claim 61, wherein said irradiating comprises:
irradiating said material having said acceptor group comprising at least one of:
where * indicates the point of attachment of the accept to a π bridge via a single bond.

### Claim 79 (depends on 61)

The device of claim 61, wherein said combiner is configured to combine the two parts of the optical pulse non-collinearly.

### Claim 80 (depends on 79)

The device of claim 79, wherein said detector is configured to measure a spectrum of one of a plurality of third harmonic signals generated in directions that are different from directions of the two parts of the optical pulse as a function of the time delay between the two parts of the optical pulse.

### Claim 81 (depends on 80)

The device of claim 80, wherein the extractor is configured to extract a phase of the optical pulse from the measured spectrum as a function of the time delay of said one of a plurality of third harmonic signals.

### Claim 82 (depends on 61)

The device of claim 61, wherein said extractor is configured to determine, from a spectrally resolved third harmonic signal as a function of the time delay, a phase of said optical pulse.

### Claim 83 (depends on 61)

The device of claim 61, wherein said optical pump is configured to generate a telecommunications laser pulse in a range from 1.4 to 1.6 microns.

### Claim 84 (depends on 83)

The device of claim 83, wherein said extractor is configured to determine a pulse duration for said telecommunications laser pulse.

### Claim 85 (depends on 84)

The device of claim 84, wherein said extractor is configured to determine at least one of a pulse width, a pulse shape, and a phase of said telecommunications laser pulse.

### Claim 86 (depends on 84)

The device of claim 84, wherein said extractor is configured to determine at least one of a pulse width and a pulse shape of ultra-fast lasers having a pulse width of less than 100 picoseconds.

### Claim 87 (depends on 45)

The device of claim 45, further comprising:
an optical divider and combiner configured to interact two time delayed optical pulses of the laser light in the material to thereby generate said third harmonic signal.