scholarly journals Evaluation of Performance Enhancement of Optical Multi-Level Modulation Based on Direct Modulation of Optically Injection-Locked Semiconductor Lasers

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 130
Author(s):  
Hyo-Sang Jeong ◽  
Jun-Hyung Cho ◽  
Hyuk-Kee Sung
Keyword(s):  
Semiconductor Lasers ◽  
Performance Enhancement ◽  
Q Factor ◽  
Frequency Detuning ◽  
Direct Modulation ◽  
Evaluation Of Performance ◽  
Shift Keying ◽  
Eye Opening ◽  
Free Running ◽  
Multi Level

The performance of optical M-level (multi-level) amplitude shift keying (ASK) modulation is improved by directly using modulated optically injection-locked (OIL) semiconductor lasers. The direct modulation performance of free-running and OIL semiconductor lasers is evaluated and compared theoretically based on coupled-rate equation. We have found that OIL semiconductor lasers can significantly improve the modulation performance in terms of the signal eye opening and Q-factor. Additionally, we found that the Q-factor increases even more in the negative frequency detuning range due to its dependence on the locking parameters.

scholarly journals Modulation Performance Enhancement of Directly Modulated Injection-Locked Semiconductor Lasers Using an Equivalent Electrical Circuit

Electronics ◽  
2021 ◽  
Vol 10 (19) ◽  
pp. 2409
Author(s):  
Ho-Jun Bae ◽  
Jun-Hyung Cho ◽  
Hyuk-Kee Sung
Keyword(s):  
Frequency Response ◽  
Semiconductor Lasers ◽  
Integrated Circuit ◽  
Performance Enhancement ◽  
Damping Ratio ◽  
Relaxation Oscillation ◽  
Electrical Circuit ◽  
Equivalent Electrical Circuit ◽  
Direct Modulation ◽  
Locking Range

We propose an equivalent electrical circuit model to evaluate the direct modulation performance of optically injection-locked (OIL) semiconductor lasers. We modeled the equivalent circuit of the OIL laser based on alternating complex envelope representations, simulated it using the Simulation Program with Integrated Circuit Emphasis (SPICE), and analyzed the frequency response of the OIL laser. Although the frequency response of the OIL laser is better than that of a free-running laser, its 3-dB modulation performance is degraded by the relaxation oscillation that occurs during direct modulation of the semiconductor laser. To overcome this limitation and maintain the maximum modulation performance within the entire locking range, we also designed an electrical filter to preprocess the electrical modulation signal and compensate for the non-flat modulation output of the OIL laser. The damping ratio of the directly modulated OIL laser increased by 0.101 (280%) and its settling time decreased by >0.037 (44%) when the electrical compensation circuit was added, exhibiting a flat 3-dB modulation bandwidth of 28.79 GHz.

4 Gbit/s direct modulation of 1.3 μm InGaAsP/InP semiconductor lasers

1982 ◽  
Vol 18 (18) ◽  
pp. 796 ◽  
Author(s):  
K. Hagimoto ◽  
N. Ohta ◽  
K. Nakagawa
Keyword(s):  
Semiconductor Lasers ◽  
Direct Modulation

Performance Enhancement of Encoding–Decoding Multidiagonal and Walsh Hadamard Codes for Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) Utilizing Dispersion Compensated Fiber

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Majidah H. Majeed ◽  
Riyadh Khlf Ahmed
Keyword(s):  
Multiple Access ◽  
Performance Enhancement ◽  
Optical Network ◽  
Spectral Amplitude ◽  
Q Factor ◽  
Data Traffic ◽  
Eye Diagram ◽  
Multiple User ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

AbstractSpectral Amplitude Coding-Optical Codes Division Multiple Access (SAC-OCDMA) is a future multiplexing technique that witnessed a dramatic attraction for eliminating the problems of the internet in optical network field such as multiple-user access and speed’s growth of the files or data traffic. In this research article, the performance of SAC-OCDMA system based on two encoding–decoding multidiagonal (MD) and Walsh Hadamard (WH) codes is enhanced utilizing three different schemes of dispersion compensating fiber (DCF): pre-, post- and symmetrical compensation. The system is simulated using Optisystem version 7.0 and Optigrating version 4.2. The performance of the proposed system is specified in terms of bit error rate (BER), Q-factor and eye diagram. It has been observed that the compensated system based on MD code is performs much better compared to the system based on WH code. On the other hand, the compensated SAC-OCDMA system with symmetrical DCF has the lowest values of BER and largest values of Q-factor, so it is considered the best simulated scheme contrasted with pre- and post-DCF.

Performance enhancement of Raman + EYDFA HOA for UD-WDM system applications

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Anurupa Lubana ◽  
Sanmukh Kaur ◽  
Yugnanda Malhotra
Keyword(s):  
Wavelength Division Multiplexing ◽  
Performance Enhancement ◽  
Optical Amplifier ◽  
Q Factor ◽  
Channel Spacing ◽  
Average Gain ◽  
Wavelength Division ◽  
System Parameters ◽  
Gain Variation ◽  
Hybrid Optical Amplifier

AbstractIn this work, we study and analyze the performance of Raman + Erbium-Ytterbium codoped fiber hybrid optical amplifier (HOA) for an ultradense wavelength division multiplexing (UD-WDM) system having 100 channels. The system has been investigated considering initial values of channel spacing and data rate of 0.1 nm (12.5 GHz) and 100 GB/s, respectively. Initially, the two important WDM system parameters—wavelength and channel spacing—have been selected and then optimization of the proposed HOA has been performed in terms of EYDFA length, pump power and Er+ concentration to achieve higher values of average gain, Q-factor and lower gain variation ratio. The optimized configuration of the HOA results in the achievement of higher value of average gain, Q-factor and gain variation ratio of 47 dB, 14 and 0.14, respectively, which confirms its viability for UD-WDM system applications.

scholarly journals Analytical Models for the Computation of Error Probability of Multi-Level Phase Shift Keying Modulation Scheme

2021 ◽  
Vol 4 (1) ◽  
pp. 13-20
Author(s):  
Isaac A. E. ◽  
Dike H.U.
Keyword(s):  
Phase Shift ◽  
Error Probability ◽  
Error Function ◽  
Density Ratio ◽  
Analytical Models ◽  
Modulation Scheme ◽  
Noise Power ◽  
Phase Shift Keying ◽  
Shift Keying ◽  
Multi Level

In this paper, analytical models for the computation of error probability (BER) of the Multi-level Phase Shift Keying (MPSK) modulation scheme is presented. Analytical models for computing MPSK bit error probability based on Q function, error function (erf) and complementary error function (erfc) are presented. Also, an analytical model for computing the symbol error rate for MPSK is presented. Furthermore, a generalized analytical expression for BER as a function of modulation order (M) and energy per bit to noise power density ratio (Eb/No) is presented. The BER was computed for various values of M (2 ≤ M ≤ 256) and Eb/No (0 dB ≤ Eb/No ≤ 14 Db). The results showed that at Eb/No =12 dB, a BER of 9.006E-09 is realized for M =2 and M =4 whereas BER of 1.056E-01 is realized for M = 256. Also, for the same M = 2 , the value of BER decreased from 1.2501E-02 at Eb/No = 4 dB to 9.0060E-09at Eb/No =12 dB. Generally, the results showed that for the MPSK modulation scheme, for a given value of Eb/No, the lower modulation order (M) has a lower BER and for a given modulation order, (M) the BER decreases as Eb/No increases.

scholarly journals MITIGATING THE INFLUENCE OF DENSE OIL FIRES ON FREE-SPACE OPTICAL COMMUNICATION

2020 ◽  
Vol 3 ◽  
pp. 69-74
Author(s):  
Thoalfiqar Ali Zaker ◽  
Talib Zeedan Taban ◽  
Firas S. Mohammed
Keyword(s):  
Free Space ◽  
Divergence Angle ◽  
Q Factor ◽  
Free Space Optical ◽  
Beam Angle ◽  
Eye Diagram ◽  
Optical Propagation ◽  
Space Optical Communication ◽  
Eye Opening

This study estimates the performance of a free space optical system (FSO) affected by air pollutants from oil fires. Simulations are performed to evaluate the reliability of optical propagation according to the length of the FSO channels under two beam angle angles. The proposed FSO system parameters such as the Q-factor, BER and reception capacity are successfully used to reduce channel loss. Results demonstrate that the proposed FSO link performs satisfactorily when the divergence angle is 1 mrad and the distance is from 0.5 km to 0.9 km. Q-factor and receiving power decrease when the divergence angle of beam increases to 2 mrad, and a link is achieved when the distance is from 0.5 km to 0.7 km. The eye diagram is used to evaluate and confirm the quality of received data. An eye opening is observed at 0.5 km for both divergence angles. Then, the eye completely closes at 1 km for 2 mrad, thereby degrading the performance. Therefore, these results can be conducted for similar systems optimization options by applying our analysis

Direct modulation of semiconductor lasers

1970 ◽  
Vol 58 (10) ◽  
pp. 1457-1465 ◽  
Author(s):  
T.L. Paoli ◽  
J.E. Ripper
Keyword(s):  
Semiconductor Lasers ◽  
Direct Modulation
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