Session Index

Optical Waveguides and Communications

Optical Waveguides and Communications I
Thursday, Dec. 3, 2020  13:15-14:45
Presider: Prof. Yung-Jr Hung
Room: 6AB Room 227
13:15 - 13:45 Manuscript ID.  0814
Paper No.  2020-THU-S0201-I001
Invited Speaker:
Boon S. Ooi

Single-Frequency Visible Laser and Vertical Cavity Surface Emitting OAM Laser for Optical Wireless Communication
Edgars Stegenburgs;Andrea Bertoncini;Jorge A. Hulguin-Lerma;Meiwei Kong;Abderrahmen Trichili;Omar Alkhazragi;Xiaobin Sun;Mohd Sharizal Alias;Tien Khee Ng;Mohamed-Slim Alouini;Carlo Liberale;Boon S. Ooi

High spectral-capacity optical wireless communication is envisaged for beyond 5G network using laser beam, which requires further advances in laser technology. In this talk, we discuss the recent achievement of single-frequency 480-nm and 514-nm visible lasers of 10.5 Gbit/s, and 940-nm VCSEL with integrated spiral-phase-plate at 1.8 Gbit/s.

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13:45 - 14:15 Manuscript ID.  0819
Paper No.  2020-THU-S0201-I002
Invited Speaker:
Silvano Donati

Developing 3-D Imaging and LiDAR Sensors: Problems and Technologies
Silvano Donati;Wood-Hi Cheng

In this paper we discuss the technologies developed for 3-D imaging-taking cameras, also variously called 3-D rangefinders, telemeters or LiDAR, and their applications to a number of scientific, industrial, biomedical and automotive fields.
We start from the description of the basic configurations used to build single-point laser rangefinders, that is, (i) triangulation, (ii) time-of-flight and (iii) interferometry, and then analyze the system requirements on parameters like: covered range, illumination power, detector noise, and stray light.
First, we illustrate how triangulation offers a relatively simple optical setup and is capable of reaching sub-mm resolution on distances up to several meters, provided the parallax base of observation is sizeable, and also yields the 3-D capability with either fan-beam scanning or image processing of the camera data. Variants of triangulation like Moire' contouring and spot array projection will also be mentioned.
Second, we analyze time-of-flight (ToF) rangefinders, that can take two different formats according to the choice of the source, i.e., the pulsed and the sine-wave techniques. Common to both are the power budget and the system equations, that we will briefly outline to calculate the achievable resolution, expressed as a characteristic time divided by the square root of received photons, where time is the pulse duration for the pulsed and the inverse pulsation frequency for the sine-wave. We consider development issues for ToF telemeters, like single vs double optics, choice of frequency, ambiguity range and index-of-refraction correction, and thereafter we present some examples of applications to topography and geodesy.
Third, we briefly report on interferometric pickup of 3-D distance data, showing that the main source of error – the speckle pattern phase error introduced by a normal diffusing target surface – can be tamed down to 5-10 micrometer by appropriate choice of the spot size and distance.
Moving on to 3-D imaging, the limitations obtained by simple, scanning beam extension of single-element rangefinders are addressed to motivate the quest for image-level processing of rangefinder data, that is, the development of a 3-D smart pixel camera in which each pixel integrates, along with the detector, all the functions of a full rangefinder.
Then we describe two approaches to smart-pixel 3-D developed in the frame of European Community Research programs: (i) the Megaframe (MF) pulsed ToF, based on an SPAD array and a smart pixel incorporating detector, preamp, TAC, logic selector, line driver, memory, and voltage converter integrated in a single 50x50 sq-micron pixel of a 128x128 array, and (ii) the sine-wave detector-demodulator (swDD) with a switching element integrated with a pin photodiode to realize the 4-phase demodulation of the delayed sine-wave received at the photodetector on a 120x160 pixel array. The fill-factors of the two approaches are 8% for the MF – requiring a micro-lens array for a recovery to a reasonable 50-60%, and 24 % for the swDD, while the chip size is 16x16 sq-mm and 2.5x2.5 sq-mm, respectively.
Finally, we consider in some detail the application of 3-D rangefinders to the automotive field, as anti-collision sensors as well as autonomous driving. The ToF is favored for best matching to performance (distance and accuracy) specifications, while a slow-pulse version of the pulsed telemeter is preferred to satisfy the laser safety requirement (1.05-mW at 900 nm and 10-mW at 1500 nm). An example of LiDAR integrated in the car headlight will be presented.
S. Donati: "Electro-Optical Instrumentation - Sensing and Measuring with Lasers" a volume of XVIII+425 pages, bound, 2004, Prentice Hall, USA, ISBN 013 0161610-9.
G.-F. Dalla Betta et al.: "Design and Characterization of Photonic Demodulators in 0.18-µm CMOS Technology", IEEE Trans. Electron Devices, vol.58, (2011), pp.1702-1709.
S. Donati, G. Martini, E. Randone: "Improving Photodetector Performance by means of Micro-optics Concentrators", IEEE J. Light. Techn., vol.29, 2011, pp.661-665.
C.-N. Liu et al: "LiDAR-Embedded Smart Laser Headlight Module Using a Single Digital Micromirror Device for Autonomous Drive" Proc. CLEO 2020, San Jose May 11-15, conference in streaming, paper ATu3T.2.

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14:15 - 14:30 Manuscript ID.  0501
Paper No.  2020-THU-S0201-O001
Rui Lin Chao
Three-Port Optical Phase-Shifters and Modulators with Ultra-High Modulation Efficiency, Positive RF-Linking Gain, and Low Residual Amplitude Modulation
Rui Lin Chao;Zohauddin Ahmad;Jin-Wei Shi

Three-port PNP-BJT configuration phase-shifter is demonstrated. Carrier injection induces more conspicuous changes of refractive index hence exhibits small Vpi (0.18V), Ppi(0.21mW). Fast rise/fall time (~1ns), small residue-amplitude-modulation (RAM) are also recorded (0.18dB). +4.0 dB RF-linking gain under dynamic operation proves three-ports to be more efficient than two-port counterpart.

14:30 - 14:45 Manuscript ID.  0065
Paper No.  2020-THU-S0201-O002
Ika Novitasari
Design of Hybrid Active III-V/SOI Photonic Devices Based on Lateral GACC Methods
Ika Novitasari;San-Liang Lee

Designing hybrid photonic devices with lateral GACC methods allows to integrate III-V and SOI materials by a standard active structure, a 220 nm Si waveguide, and an adhesive bonding layer. 87% coupling efficiency is demonstrated at 1550 nm wavelength.