About photonic Using Compute Engine with An Optical Phased Array

[Alexander Morozov]

1. In the patent "Photonic Ising Compute Engine with An Optical Phased Array" (https://patents.google.com/patent/U...g+Compute+Engine+with+An+Optical+Phased+Array) dated 2023-05-11 and the article "Scalable and ultralow power silicon photonic two-dimensional phased array" (https://pubs.aip.org/aip/app/articl...lable-and-ultralow-power-silicon-photonic-two) dated January 2023, the authors, led by James Leatham from the Raytheon Intelligence & Space laboratory, study the construction of a computer from an optical phased array, and for better control of the electromagnetic field, they propose to use attenuators\amplifiers.

2. In “On the control of the electromagnetic field in a space. Continuation” (https://www.eng-tips.com/viewthread.cfm?qid=505072) it is assumed that a periodic array of radio components with wireless distributed communication allows you to control and transform the spatial spectrum of the electromagnetic field only by phase shifters. In the radio range, these can be varicaps, and what's the best thing about optics?

Is it useful to combine these two observations when building high-speed optical calculators with vector-matrix control?

 

[BradtheRad]

Optical computing provides an advantage because it generates no heat. It needs no return path for electrons.

From what I know about phased arrays it's a technique to beam a pulse in any direction, by turning on rows of emitters in rapid succession. Timing is precise so their individual emissions combine into a united wavefront.

In optical computing a technique of writing to memory... construct a grid of cells (resembling a movie screen), and a phased array projector placed at a distance so it can access all cells. The projector sends a beam toward one cell, changing its state.
I'm not sure how the cell can be read.

The the patent mentions amplifiers and implies electronic circuits are needed to supplement the optical computing sections.

Patent documents often give incomplete descriptions. I believe authors frequently omit crucial details. After all, with a full explanation someone else might succeed at building a working model and make profit.

 

[dick_freebird]

I think it's going to be "interesting" trying to manipulate
optical phase-front inthe same ways that people have
done RF phased arrays. Just temperature variation alone
(from end to end) would seem a problem, when the
emitter alone often must be temperature controlled to
keep laser on point. So what about the harness and the
panel, their contribution to the final emitted phase of any
given element?

 

[Alexander Morozov]

Thank you.
Objectives of the optical computer:
- “Optical computing provides an advantage because it generates no heat. It needs no return path for electrons”,
- increasing the speed of computing (the clock frequency can be much higher than the units of GHZ of modern electronic computers),
- size reduction,
- during calculations, the ability to control the electromagnetic field in space as in phased arrays (for frequencies units of GHZ, the dimensions of radio arrays are measured in meters, in optics – in microns),

I assume that the classical control of the field by phase shifters\attenuators\amplifiers does not provide control with the greatest benefit for calculations. For example, it is impossible to create a radiation pattern as in FIG. 4 without large energy losses of controlled light using a phased array with FIG. 1. But the diagram with FIG. 2 has such an opportunity, if in the optical range it is possible to make a phase shifter with the diagram of FIG. 3. In this case, the energy is not absorbed \amplified, but redistributed in the control channels. This creates additional opportunities for transmitting binary information.

I studied such method of controlling the microwave field in the USSR, but now only technologies are available to me https://www.eng-tips.com/viewthread.cfm?qid=460973 . For example, JAMES G. LATHAM, head of the RAYTHEON TECHNOLOGIES laboratory, has such technologies and he can make the phased array with diagram FIG. 2. I wrote to them in vain, so I'm trying to find out the opinion of engineers about the usefulness of such field management. Some details are described in the links from the first message.

FIG. 1 from the https://www.semanticscholar.org/pap...iasl/5541dd9450564fdd60fdf8fc622246025700a4ba (Fig. 6).
FIG. 2, FIG. 3 from the https://www.eng-tips.com/viewthread.cfm?qid=505072 (Fig. 1)

 

[Alexander Morozov]

But it wasn't my idea, it was JAMES G. LATHAM, head of the RAYTHEON TECHNOLOGIES laboratory, deeply respected Cherokee Indian. I only propose to improve the quality of control of the electromagnetic field, including light.

 

[Alexander Morozov]

I assume that a more complex field control is useful for solving the JAMES G. LATHAM problem than in radar and wireless communications.

 

[BradtheRad]

Lenses and prisms are commonly used to bend light rays. Is that the sort of control of electromagnetic fields needed to refine and develop optical computing?

I think we need to develop a means to change the shape of glass or clear plastic (or other substance) in order to aim light beams in any direction. That could make it possible to develop optical computing and random memory storage, etc.

 

[Alexander Morozov]

That's right, but there are nuances.
1. The dielectric lens controls the electromagnetic field in space. Its properties are constant in time.
In FIG. 5 from the message of July 7, 2020 in https://www.eng-tips.com/viewthread.cfm?qid=461144 the focusing lens is shown. Pay attention to its sizes. I assume that it is possible to calculate and make such a lens so that at a fixed frequency the diffraction losses will be record low at such sizes. This is useful for transmitting energy over long distances. Micro-CAP12 suggests that if a wide frequency band is needed, for example, for an electromagnetic field with pulse modulation, then it is possible to increase the thickness of the lens and complicate its dielectric structure. At the same time, the thermal losses in the dielectric will increase. I read that there are tasks when the customer agrees to large thermal and diffraction losses for the sake of working in a certain frequency band. Where is the limit of acceptable losses? I don't know.

2. On the control of electromagnetic field in time.
It was assumed In Soviet textbooks that the controlled power splitter should only to share the energy of the microwave field without phase control, and the phase shifter – on the contrary.
FIG. 3 is the simplest device that simultaneously control both the coupling factors and the phases in the coupled channels. This is an imitation of the dielectric medium. The refractive index in it changes at the request of the engineer. FIG. 6 shows a possible array of phase shifters from coupled resonators. Such resonators are well studied. Their refractive index is changed by heating, changing voltage or current. A circle on the picture may mean a complex structure that provides control of the phase\amplitude of the field and the smallest diffraction scattering. Now such a structures is well simulated in various ways.

 

[Alexander Morozov]

И еще.
На FIG. 4 изображена диаграмма направленности (распределение поля в дальней зоне) по желанию JAMES G. LATHAM. Но такой двоичный (бинарный) образ можно создать на любой(?) поверхности между дальней зоной и раскрывом\апертурой решетки излучателей. Micro-CAP12 это разрешает.
А как на самом деле?
Это полезно?
Черт его знает!

[Google translation added by moderator]
And further.
On FIG. 4 shows the radiation pattern (field distribution in the far field) as desired by JAMES G. LATHAM. But such a binary (binary) image can be created on any (?) surface between the far zone and the opening / aperture of the emitter array. Micro-CAP12 allows this.
How about really?
This is useful?
The devil knows!

 

[Alexander Morozov]

That's great! This is the first time I see such a forum.