High speed free-space optical communication using standard fiber communication component without optical application by Nazmul Akter Shahin.pptx

High speed free-space optical communication using standard fiber communication component without optical application by Nazmul Akter Shahin

1. High speed free-space optical communication using standard fiber communication component without optical amplification Presented by Md Rakibul Islam ID:1502246 Nazmul Akter Shahin , ID: 2405141 ECE581- Free Space Optical Communication Department of Electronics and Communication Engineering ( ECE) Hajee Mohammad Danesh Science and Technology University,Dinajpur 5800 Submitted To : Dr . Nasrin Sultana Associate Professor Department of Electronics and Communication Engineering Hajee Mohammad Danesh Science & Technology University, Dinajpur .

2. 2 What is FSO? Free-space optical (FSO) communicate without fiber optic cables. It uses modulated laser beams to transmit data wirelessly through air, space, or vacuum.

3. 3 Abstract Achieved 9.16 Gbps over 1 km without amplification . Developed miniaturized FSO system (9.5 kg ) 4-stage APT system → tracking error < 3 μrad , link loss 13.7 dB Tested up to 4 km (limited by fog, 18 dB loss)

4. 4 Introduction FSO Applications: Satellite internet ( Starlink )Last-mile access, disaster recovery, military links Challenge : Accurate Acquisition, Pointing, Tracking (APT) in small form factor Traditional solution: Optical amplifiers (EDFA) Erbium-doped optical fiber amplifier → but add weight, power, complexity Low link loss (13.7 dB) using compact 4-stage APT + stabilization

5. 5 Introduction (cont’d) Both ends use identical optical aperture & mechanical design Each device includes: Optical transceiver module, APT unit, Control electronics SMF-coupled nodes → direct use of commercial transceivers for bidirectional communication

6. Objectives Design lightweight and portable FSO devices Achieve high data rates without optical amplifiers Ensure low link loss via advanced APT system De monstrate stable communication up to several kilometers 6

7. FSO Device Design 7 Optical transceiver module + APT system Reflective Cassegrain optical antenna (90 mm) Beacon lasers for coarse and fine tracking CMOS sensors for error detection FIG. 2. (a) The design of an FSO device. L, lens; IF, interference filter; DM, dichroic mirror; WDM, wavelength division multiplexer; TOSA, transmitter optical sub-assembly module; ROSA, receiver optical sub-assembly module. CMOS, complementary metal oxide semiconductor; BL, beacon laser; FSM, fast steering mirror system. (i = 1, 2)

8. APT Operation 8 Active stabilization uses IMU signals to cancel vibrations . Initial acquisition uses RTK positioning to align the gimbal . Coarse tracking follows BL0 via CMOS0 . Fine tracking is refined in two stages using CMOS1/FSM1 and CMOS2/FSM2 for high accuracy Figure: (b) The operation schematic of the APT system for acquisition and coarse tracking (left), fine tracking (right).  

9. APT Performance Table 9 Component Specification Coarse Tracking Mechanism 3-axis motorized gimbal Azimuth: ±90° Pitch: ±60° Roll fixed Coarse Tracking Sensor CMOS FOV: 0.04 rad × 0.04 rad Resolution: 288×288 px Frame rate: 1 kHz Power: 1 W Beacon Laser 0 Wavelength: 940 nm Divergence: 35 mrad Fine Tracking Mechanism FSM Range: ±212 μ rad Fine Tracking Sensor CMOS FOV: 13×10 mrad Resolution: 288×288 px Frame rate: 1 kHz Power: 5 mW Beacon Laser 1 Wavelength: 638 & 660 nm Divergence: 6 mrad Power: 5 mW Beacon Laser 2 Wavelength: 808 & 852 nm Divergence: 6 mrad

10. Coarse Tracking Results 10 Figure: Performance of the APT system measured with 1 km separation.- (a) The coarse tracking error. 1 km test Average tracking error: 24 μ rad Std. deviation: 34.6 μ rad (pitch), 20.9 μ rad (azimuth) Reasonable initial stability

11. Fine Tracking Results 11 Fine tracking ON after 30s Error reduced 24 μ rad → 3 μ rad Std. deviation: 2.9 μ rad (pitch), 3.9 μ rad (azimuth) Ensures stable FSO link Figure: Performance of the APT system measured with 1 km separation.- (b) The fine tracking error.

12. Link Loss Measurement 12 First-stage fine tracking: 29.3 dB loss Second-stage fine tracking: 13.7 dB loss Significant improvement due to multi-stage APT Figure: (a ) Link loss for 1 km FSO.

13. Communication Modules 13 Commercial 10 Gbps optical transceiver modules TOSA (transmitter) + ROSA (receiver) Compact, compatible with standard fiber systems Figure : Picture of the optical transceiver modules.

14. Bandwidth Test 14 Direct fiber: 9.27 Gbps avg. 1 km FSO: 9.16 Gbps avg. Almost identical performance → validates design Figure : Communication bandwidth measurement for the module test and FSO. Red: direct connection test; Blue: 1 km FSO test.  

15. 4 km Link Performance 15 Average link loss: 18 dB Maximum loss: 27.8 dB (unstable in fog) With better weather/EDFA, longer distances possible Figure : Link loss for 4 km FSO.

16. Applications 16 High-speed wireless data: last-mile, 5G backhaul Satellite networks ( Starlink -like systems) Military and disaster recovery Quantum communication potential

17. Conclusion 17 9.16 Gbps FSO achieved at 1 km without amplification Lightweight (9.5 kg), compact, field-deployable APT system ensures low error and stability Potential for longer distances & quantum communication

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19. T HANK Y OU