[Laser] Optical Beam-Steering

[Glenn Thomas]

Interesting idea. Most semiconductor lasers have very poor phase 
coherence (let alone phase stability) because of thermal Doppler shift 
due to the lasing medium not being anywhere near absolute zero. The 
result of this is that most RF techniques based on constant or 
controllable phase or frequency don't work very well in the optical domain.

How does this proposed phased-array scheme get around thermal 
frequency/phase noise issue?

Can you provide a better link to the article/book? I didn't see anything 
quite like this in a Google search.


On 3/22/2013 4:36 AM, John McNulty wrote:
> Optical Beam-Steering
> Ian S. Osborne
> Antenna arrays have long been used for communication and sensing purposes. In the microwave and radio wavelength regime of the electromagnetic spectrum, arrays of antennas in which the phase and amplitude input to each element is varied can provide tailored beam profiles with controlled directionality. Applications can be found across many fields, from target tracking and guidance to astronomy and weather observations. Carrying over the principles of phased-array antenna technology, DeRose et al. have developed an optical phased array based on metallic nanoemitters patterned on a complementary metal-oxide semiconductor (CMOS)–compatible substrate. With the input to each antenna element fed in using a coupled waveguide integrated with a phase shifter, they show that electrical control of the phase results in wide-angle beam-steering capability. Operating at near-infrared wavelength, the ability to manipulate an optical beam over a two-dimensional area should find use in compact high-speed communication over free space.
>
> Opt. Express 21, 5198 (2013).