Atmospheric effects on near-infrared free space optical communication links

Ikpe, Stanley A.

doi:10.32469/10355/6654

Cited by 1 publication

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“…CCRs can also be substituted with other reflective optics such as a DBR [6]. Even though a MRR link is susceptible to the same atmospheric effects as other FSO communications links, studies have suggested that increasing the transmission wavelength into the mid-infrared (MIR) regime and beyond may significantly improve signal transmission [11][12][13]. Adapting an MRR device for mid-infrared operation becomes a natural progression, and this process includes the careful selection of compatible semiconductor materials and design of a monolithic structure capable of both absorbing and reflecting the desired MIR wavelength.…”

Section: Introductionmentioning

confidence: 99%

Improved optical resonance in mid-infrared GaAs-based modulating retro-reflectors

Ikpe

Triplett

2015

SPIE Proceedings

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In this work, we studied a mid-infrared modulating retro-reflector (MRR) design that is GaAs-based because of the flexibility to monolithically incorporate reflective optics along with quantum well modulator region. Using solid-source molecular beam epitaxy, we produced MRR devices, where the GaAs quantum well(s) in the modulator region contained Al x Ga 1-x As barriers to tune the wavelength selectivity beyond three microns. The width of the quantum well was also adjusted in order to achieve free electron absorption within the confined energy subbands and modified by way of the quantum confined Stark effect. When the applied electric field varies in polarity, intensity, or frequency, the fabricated MRRs behave as an optional shutter--absorbing or transmitting the incident mid-infrared energy depending on the applied field. Our work shows that the ability for the modulating region to effectively act as a shutter for mid-infrared radiation depends on the number of cascading quantum wells, though increasing the number of wells directly increases the overall thickness of the modulating region and adversely affects the reflected power of the mid-infrared modulated beam. The shutter operation was achieved by applying an alternating square bias across the QWM region, and the speed at which the quantum wells switch from absorbing to non-absorbing was dependent on the physical size of the device. Increasing the physical size increases the associated device capacitance. The maximum achievable contrast ratio for these devices is calculated to be 1.6:1 for applied voltages between 12V and 25V.

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Section: Introductionmentioning

confidence: 99%