US 2026/0171852 A1 · OPTICAL WIRELESS POWER TRANSMISSION USING LASER DIODES

Abstract

A system for transmitting laser power to a remote receiver, comprising a laser diode, an optical system for collimating and focusing the laser beam onto the receiver, and a scanning system for directing the beam towards the receiver. The beam has a wavelength of 1150-1550 nm, has a power of >300 mW, has an emitter width of between 15 and 250 μm, and is a spatial multimode beam, having >50% of its power in the TEM00 mode, and <15% of its power in higher order TEMnm modes having (n+m)>20. The lasing cavity has a Fresnel Number between 0.01 and 20, and a slow axis M2 of <15, and a fast axis M2 of <1.5, and a fast axis divergence of <60°. The collimated laser beam has a single lobe when imaged to a range of up to 10 meters.

Claims27

Dependent claims

A laser diode emitting a laser beam for optical wireless power transmission, the laser diode comprising:

a first cladding layer having a first refractive index, and a second cladding layer having a second refractive index, between which there lies an emitting region comprising:
a positively doped layer having a third refractive index, and a negatively doped layer having a fourth refractive index, each of the third and the fourth refractive indices being larger than either of the first and second refractive indices;
and
a gain medium layer deposited between the positively doped layer and the negatively doped layer, and having an energy bandgap of between 0.8 eV to 1.2 eV,
wherein the width w, in meters, of the emitting region is within the range:
5
*
10
-
27
E
*
n
2
>
5
*
10
-
27
E
*
n
1
>
w
>
5
*
10
-
28
E
*
n
2
>
5
*
10
-
28
E
*
n
1
where E is the bandgap of the gain layer measured in Joules, n1 is the average refractive index of the doped layers, and n2 is the average refractive index of the cladding layers, and wherein:
the upper limit of w is selected to ensure that in the slow axis, the beam has a spatial multimode form of a required quality, by having at least a first predetermined percentage of its power concentrated in the Hermitian-Gaussian TEM00 mode, and no more than a second predetermined percentage of its power in higher order TEMnm modes having (n+m) greater than a preset number, and
the lower limit of w is selected to ensure that in the slow axis, the beam has sufficient combination of higher order modes so that it produces at least a required level of laser beam output power.

46 more elements

A system for transmitting laser power from a transmitter to a remote receiver, the system comprising:

a laser diode source comprising a gain medium sandwiched between p- and n-doped layers, and supplied with current from a laser driver;
an optical system for collimating the laser beam emitted from the laser diode source, to produce a spot of illumination on the remote receiver;
and
a scanning system for directing the collimated laser beam towards the aperture of a photovoltaic cell on the remote receiver;
wherein:
the gain medium of the laser diode is selected so that the laser diode emits a beam at a wavelength λ of between 1150 nm and 1550 nm;
the current supplied by the laser driver to the gain medium is selected such that laser beam has a power of at least 300 mW;
and
the laser diode source has an emitter width w of between 15 and 250 μm, such that:
the laser beam is a spatial multimode beam, having at least 50% of its power concentrated in the Hermitian-Gaussian TEM00 mode, and less than 15% of its power in higher order TEMnm modes having (n+m) is greater than 20;
and
the laser diode gain medium length is selected such that the laser diode has a Fresnel Number in a slow axis, w2/λL, of between 0.01 and 20, where L is the length of the laser cavity, yielding a beam having:
an M2 value in the direction of the slow axis of less than 15;
an M2 value in the direction of a fast axis of less than 1.5;
a divergence of the laser beam in the direction of the fast axis of less than 60°;
a single lobed mode of the collimated laser beam, when imaged by the optical system to a distance of 10 m;
and
a consequentially focused spot of the laser beam, given by the expression:
20
⁢
h
*
tan
⁢
(
6
*
10
-
7
h
)
<
r
<
10
⁢
w
2000000
*
h
2
where h is the combined height of p- and n-doped layers and the gain medium, measured in meters,
w is the width of the gain medium, measured in meters,
r is an effective radius of the focused spot, and
the tan function is in radians.

43 more elements

Dependencies are inferred from the claim text.

Optical wireless power transmission using laser diodes

Life of this patent

Optical wireless power transmission using laser diodes

Life of this patent

Abstract

Claims27