Systems and methods for spatiotemporal control of a laser and applications of same

Patent metadata

Field	Value
Publication number	US-10897115-B2
Application number	US-201715721900-A
Country	US
Kind code	B2
Filing date	Sep 30, 2017
Priority date	Sep 30, 2017
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

Methods and systems are disclosed for using a chromatic lens system to provide a “flying focus”—i.e., an advanced focusing scheme enabling spatiotemporal control of a focal location. In a method, a photon beam is emitted from a source at a wavelength. The photon beam may have more than one wavelength. The photon beam is focused to a focal location using a chromatic lens system. The focal location is at a first longitudinal distance along an optical axis from the chromatic lens system. The wavelength of the photon beam is changed as a function of time to change the focal location as a function of time. The wavelength may be changed such that the focal location changes with a focal velocity.

First claim

What is claimed is:

1. A method of spatiotemporally changing a focal location of a photon beam as a function of time, comprising:
providing a photon beam emitted from a source wherein the photon beam has a wavelength (λ);
focusing the photon beam to a focal location using a chromatic lens system, the focal location is at a first longitudinal distance (z) along an optical axis from the chromatic lens system; and
changing the wavelength of the photon beam as a function of time to change the focal location as a function of time.

2. The method of claim 1 , wherein the photon beam has more than one wavelength and the chromatic lens system is selected to define a focal location for each wavelength which is different than the focal locations of other wavelengths.

3. The method of claim 1 , wherein the chromatic lens system is a diffractive lens.

4. The method of claim 3 , wherein the diffractive lens has a radially varying groove density

G
=

r

λ
0

⁢

f
0

,

where r is a radial distance from the optical axis, λ 0 is a central wavelength, and f 0 is a focal length at the central wavelength.

5. The method of claim 1 , wherein the wavelength is changed such that the focal location changes with a focal velocity (v).

6. The method of claim 5 , wherein the focal velocity is described by the equation:

v
⁡

(
z
)

c

=

[

1
+

(

d
⁢

⁢
λ

d
⁢

⁢
τ

)

-
1

⁢

(

dz

d
⁢

⁢
λ

)

-
1

⁢
c

]

-
1

wherein,

dz

d
⁢

⁢
λ

is a longitudinal dispersion of the chromatic lens,

d
⁢

⁢
λ

d
⁢

⁢
τ

is a rate of change of wavelength of the photon beam given by λ(τ), τ is a time-space coordinate where τ=t−z/c, t is time, and c is the speed of light.

7. The method of claim 1 , wherein the focal location (z) is changed over time (z(t))
by changing the wavelength of the photon beam according to

λ
⁡

(
τ
)

=

λ
0

⁡

[

1
-

z
⁡

(
τ
)

f
0

]

-
1

,

where the
chromatic lens system has a longitudinal dispersion given by

dz

d
⁢

⁢
λ

≅

-

f
o

λ
0

,

where λ 0 is a central wavelength and f 0 is a focal length at the central wavelength.

8. The method of claim 1 , wherein the source is a broadband laser.

9. The method of claim 8 , wherein the laser uses optical parametric chirped-pulse-amplification where

d
⁢

⁢
λ

Assignees

• Univ Rochester

Inventors

• Froula Dustin H
• Kessler Terrance

Classifications

• H05H15/00 Primary

  Methods or devices for acceleration of charged particles not otherwise provided for {, e.g. wakefield accelerators} · CPC title

• H01S3/09705

  with particular means for stabilising the discharge · CPC title

• G01J11/00

  Measuring the characteristics of individual optical pulses or of optical pulse trains · CPC title

• H01S3/2308

  Amplifier arrangements, e.g. MOPA · CPC title

• G02B5/1814

  structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings (G02B5/189 takes precedence) · CPC title