Hybrid Laser-LED Transmitter With Closed-Loop Beam-Steering Control for Indoor Optical Wireless Communication

Ahmad, Faheem; Ramachandrapura, Sathisha; Manattayil, Jyothsna Konkada; Raghunathan, Varun

doi:10.1109/jlt.2022.3154540

Cited by 7 publications

(3 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If the positioning result is not sufficiently accurate and the laser spot lies off the receiving aperture, the transmitter performs a small-scale scanning until sufficient laser power arrives at the receiving aperture. This process can rely on the feedback of the received laser power information to the transmitter, which can also be realized through the aforementioned low-latency RF link [10].…”

Section: Fast Acquisition Tracking and Pointing Basedmentioning

confidence: 99%

Optical Mobile Communications: Architecture and Enabling Technologies

Zhu¹

2023

Preprint

View full text Add to dashboard Cite

<p>Modern mobile communication systems exploit complicated modulations to increase spectrum efficiency and larger antenna arrays to suppress co-channel interferences. However, these techniques have also caused surges of power consumption and hardware cost, making it unsustainable to squeeze gains from the radio-frequency electronics. To circumvent the dilemma, optical mobile communication (OMC) systems exploit wideband lasers to carry data, and do not necessarily involve high-order modulation and oversized arrays. In OMC systems, parallel laser beams can achieve data rate of Tbps, connection density of thousands of links/m$^2$, and energy efficiency of Gbits/J, with low cost and low signal processing complexity, as long as the challenges in receiver tracking, channel decorrelation and anti-blocking can be tackled. To this end, this work presents a new OMC system architecture and discusses enabling technologies of practical OMC systems. A prototype is built to verify the feasibility of several key concepts. It is shown that a practical OMC system requires collaboration of fast and accurate positioning systems, rapid laser steerers, optical reflective intelligent surfaces and decorrelation optics.</p>

show abstract

Section: Fast Acquisition Tracking and Pointing Basedmentioning

confidence: 99%

Optical Mobile Communications: Architecture and Enabling Technologies

Zhu¹

2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Locking a user's location using a pencil beam is highly unreliable for randomly moving users. One work [29] has implemented beam steering using liquid lenses with feedback and a locking mechanism, however, the time delay to lock the user's location is too long to be useful for practical scenarios. Relay-based cooperative network has been proposed to improve the VLC coverage [30]- [32] but these approaches add extra hardware to the system.…”

Section: Introductionmentioning

confidence: 99%

Coverage Improvement of Laser Diode-Based Visible Light Communication Systems Using an Engineered Diffuser

Bera,

Parthiban,

Karmakar

2023

IEEE Access

View full text Add to dashboard Cite

A combination of a blue laser diode (LD) and a warm white light emitting diode (LED) has been used for indoor lighting and visible light communications (VLC). Contrary to LD and phosphor based white lighting communication, no blue LD power is lost due to phosphor conversion. As a result, a longer communication distance has been achieved. The laser beam is diffused in a hat-top profile by an engineered diffuser in such a way that the received signal strength remains flat over a large area, thus improving the coverage area of the communication system. The experiment demonstrates a 1.7 Gbits/s communication speed over a distance of 1.85 m keeping bit error rate (BER) below 2.8 × 10 −3 over a large area. The coverage area has been improved by 238% to 2.27m 2 using the hat-top diffuser from 0.95m 2 for a phosphor diffuser. This is the largest reported coverage area for the achieved VLC speed at 1.85 m distance to the best of the authors' knowledge. A correlated color temperature (CCT) of 2952 and a color rendering index (CRI) of 86 have been achieved and the blue light exposure has been kept under the permitted limit. As the radiation standards for eye safety are more relaxed for the infrared (IR) spectrum compared to the visible spectrum, a near-IR LD has been utilized to achieve higher data rates. A data rate of 2.55 Gbits/s has been achieved using the near-IR LD and the proposed diffuser for the same coverage area and distance.INDEX TERMS Visible light communications, VLC coverage, optical wireless communications, free space optics, hybrid LED-LD, OWC, engineered diffuser.

show abstract

“…The RIS can also be used to split a single beam into many steerable beams or many incident beams, and it can steer independently as well to cater to a larger number of users [7] [8], [9]. In steering the beam non-mechanically, liquid tunable lens has also been demonstrated using the diffused near infrared (NIR) laser for indoor application [10] . For the downlink channel, energy efficiency optimization is investigated for RIS assisted VLC system [11].…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable multi-beam steering using segmented spatial light modulator for indoor optical wireless communication

Ahmad

Raghunathan²

2023

Next-Generation Optical Communication: Components, Sub-Systems, and Systems XII

View full text Add to dashboard Cite

Spatial light modulators (SLM) are experimentally characterized to be used as reconfigurable-intelligent surfaces (RIS) for smart beam steering of multiple beams for indoor optical wireless communication application. The SLM surface is segmented into two separate regions to perform multibeam steering of two separate incident laser beams to two user devices. Beam steering is achieved here by applying blazed-grating and de-centered lens profile using liquid-crystal-onsilicon (LCoS) phase-only SLM. Experimental measurements of beam steering using blazed grating profiles results in ±3.6 ° steering. The first-order diffraction efficiency decreases from 54.5% to 21.8% for right half and 39.8% to 14.5% for the left half SLM with increase in steering angle as a function of decreasing in blazed grating pitch. The blaze grating-based beam steering is however prone to blind zones in which steering is not possible and the non-linear dependence of the steering angle on grating pitch. To overcome these limitations, we investigate de-centered lens profile as a mechanism to steer the beam. This results in a linear relationship between lens decentring of the lens profile and steering at high resolution. The measured resolution with this technique is ~0. 0018 °/pixel with angular span of ±4.26 °. The first-order diffraction efficiency is found to be varied from 40.1% to 8.5%. We have also designed additional magnification optics to further increase the above steering angle by a factor of 10-times using Zemax-based ray-tracing.

show abstract

Hybrid Laser-LED Transmitter With Closed-Loop Beam-Steering Control for Indoor Optical Wireless Communication

Cited by 7 publications

References 48 publications

Optical Mobile Communications: Architecture and Enabling Technologies

Optical Mobile Communications: Architecture and Enabling Technologies

Coverage Improvement of Laser Diode-Based Visible Light Communication Systems Using an Engineered Diffuser

Reconfigurable multi-beam steering using segmented spatial light modulator for indoor optical wireless communication

Contact Info

Product

Resources

About