Receiver Sensitivity Research Articles

Optimization of MEMS Matching Network for the Sensitivity of GHz Low-Power Wake-Up Receivers

Optimization of MEMS Matching Network for the Sensitivity of GHz Low-Power Wake-Up Receivers

Correlation between handgrip strength and air trapping in patients with stable chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) often presents with dyspnea resulting from the condition of air trapping, assessed by lung volume measurement studies. This study aimed to investigate the relationship between handgrip strength (HGS) and air trapping in COPD patients. Cross-sectional research was conducted in COPD patients at Thammasat University Hospital, Thailand between May 2022 and December 2023. HGS was assessed using the Jamar® Smart Hand Dynamometer, and air trapping was measured using a body plethysmograph. Air trapping was defined as a ratio of residual volume (RV) to total lung capacity (TLC) greater than 40%. Receiver operator characteristic (ROC) curves, sensitivity, and specificity values were calculated to determine the optimal cutoff value of HGS for predicting air trapping. A total of 72 patients (90.3% male) were included, with an average age of 72.4±9.7 years. The body mass index was 23.5±4.3 kg/m2. The smoking history was 23.2±14.8 pack-years. Common comorbidities included hypertension (36.1%) and diabetes (22.2%). Post-bronchodilator forced expiratory volume in 1 second (FEV1) was 72.1%±21.2%. Air trapping was found in 55.6%. A negative correlation was found between HGS and RV/TLC (R=-0.399, P=0.001). The best cutoff value for HGS to predict air trapping was 28.3 kg, with 71.9% sensitivity and 65.0% specificity. The area under the ROC curve for identifying air trapping was 0.681 (95% CI: 0.554 to 0.808, P=0.009). Air trapping is common in COPD patients, and HGS is significantly correlated with air trapping. Thus, HGS may serve as an alternative tool for assessing air trapping.

Cut-off point development for the Everyday Memory Questionnaire – Revised in perimenopausal women

Objective Subjective cognitive complaints have been reported in women during perimenopause and the Everyday Memory Questionnaire – Revised (EMQ-R) has been recently evaluated as a standardized instrument to measure subjective cognitive changes. The purpose of this study was to identify potential cut-off points for the EMQ-R retrieval subscale and attentional subscale, and to assess the validity of these cut-off points in detecting objective cognitive changes associated with reported subjective cognitive complaints. Method After screening, 232 perimenopausal women were included in the analyses. The supervised classification and regression tree was applied to identify optimal cut-off points. Its performance was evaluated by the value of the receiver operating characteristics curve, sensitivity and specificity. Results Findings revealed that the optimal cut-off point for the attentional subscale was 7, and for the retrieval subscale was 13. Both cut-off points presented acceptable discrimination performance. An independent t-test indicated that both cut-off points were associated with significant differences in scores on neuropsychological measures of retrieval (episodic memory and verbal fluency) as well as neuropsychological measures of higher-level attention (working memory). Conclusion The identified cut-off points may be helpful for women to track or quantify their subjective experiences of brain fog or cognitive symptoms during the menopause transition.

Highly secure non-orthogonal multiple access with key accompanying transmission based on subcarrier-indexed modulation.

This paper proposes a key-accompanying transmission scheme based on subcarrier indexed modulation (SIM). The key is used to control the activation state of subcarriers, with key masking achieved through the position information of silent subcarriers, which enables the cooperative transmission of both key and primary messages. Meanwhile, a four-dimensional hyperchaotic model is adopted to ensure system security. By utilizing power multiplexing, the scheme realizes the parallel transmission of two signals and disrupts the carrier frequency and symbol of the original signals. The scheme is experimentally demonstrated with a 54.25 Gb/s SIM-chaotic power division multiplexing (CPDM) signal transmission over 2 km of 7-core fiber.. The results indicate that the proposed scheme does not degrade system transmission performance at either high or low power levels. At the limit of forward error correction (FEC)=3.8×10-3, the impact of our scheme on receiver sensitivity is no greater than 0.1 dB. The accuracy and sensitivity of the key are maintained, with the transmission performance of the key remaining excellent. The bit error rate (BER) for the main signal is consistently kept at 0, while the BER for the key rises to around 0.5 if the key is misaligned by one bit. Moreover, the key space can reach 10135, effectively verifying the system's high security.

End-to-end learning of joint noise shaping and probabilistic shaping for OAM mode division multiplexing transmission.

Intensity modulation direct detection (IM/DD) orbital angular momentum (OAM) mode division multiplexing (MDM) technology can greatly expand the capacity of a communication system, which is a promising solution for the next generation of high-speed passive optical networks (PONs). However, there are serious obstacles such as mode coupling, device nonlinear impairment, and quantization noise in an IM/DD OAM-MDM system with a low-resolution digital-to-analog converter (DAC). In this Letter, we propose a novel, to the best of our knowledge, end-to-end (E2E) learning scheme based on a double residual feature decoupling network (DRFDnet) emulator with joint probabilistic shaping (PS) and noise shaping (NS) for the OAM-MDM IM/DD transmission. Our DRFDnet emulator can accurately build a complex nonlinear model of an OAM-MDM system by separating the signal impairments into linear and nonlinear. Meanwhile, a DRFDnet-based E2E scheme for joint PS and NS is presented with the aim of compensating the signal impairment for the OAM-MDM IM/DD system. An experiment is carried out on a 200 Gbit/s PON system based on the OAM-MDM IM/DD transmission. The experimental results demonstrate that the proposed DRFDnet-based joint PS and NS scheme is a promising solution to effectively mitigate nonlinear distortions and outperforms the CGAN-based joint PS and NS scheme and traditional joint PS and NS scheme with receiver sensitivity improvements of 1.2 dBm and 2.5 dBm under hard-decision forward error correction (HD-FEC) thresholds, respectively. Our experimental results demonstrate that the proposed DRFDnet emulator-based E2E learning scheme is a viable candidate for future PON.

Digital pre-equalization for performance improvement in coherent PON

As high-speed optical access networks continue to evolve, reducing the computational complexity at the optical network unit (ONU) side remains a significant challenge in coherent passive optical network (PON). This paper presents a pre-equalization scheme that integrates digital pre-distortion (DPD) and pre-emphasis techniques in 200 Gb/s coherent PON. The focus is on three modulation formats: 50 Gbaud polarization multiplexing-quadrature phase shift keying (PM-QPSK), 50 Gbaud Alamouti-coded polarization multiplexing-16 quadrature amplitude modulation (PM-16QAM), and 25 Gbaud PM-16QAM, using intradyne or heterodyne detection schemes. Through comprehensive numerical simulations and experimental evaluations, we demonstrate significant improvements in receiver sensitivity and power budget in 200 Gb/s coherent PON. When the number of digital filtering taps is small, the proposed scheme achieves power budget enhancements of 3 dB for 50 Gbaud PM-QPSK, 7 dB for 50 Gbaud Alamouti-coded PM-16QAM, and 2.1 dB for 25 Gbaud PM-16QAM in the downlink. These findings highlight the potential of pre-equalization techniques in enhancing the performance of next-generation coherent PON with low computational complexity at the ONU side.

Polar coded SCMA-OCDM based on chaotic scrambled SLM.

In this work, the polar coded sparse code multiple access (SCMA) scheme based on chaotic scrambled selective mapping (CS_SLM) is proposed for future passive optical networks (PONs). The original bits are coded by polar and mapped into constellation symbols by sparse code. Then orthogonal chirp division multiplexing (OCDM) modulation is adopted which has better anti-interference ability than orthogonal frequency division multiplexing (OFDM). At the receiver, the joint iterative detection and decoding for polar and SCMA is used to further improve the BER performance. The CS_SLM is helpful to improve the reliability and security, while keeping high spectral efficiency of SCMA-OCDM modulation. A 49.42 Gb/s coded SCMA-OCDM PON over 2 km seven-core fiber is demonstrated in the experiment. The results show that the SCMA-OCDM scheme gets a receiver sensitivity of 0.8 dB at a bit error rate (BER) of 3.8 × 10-3, compared with SCMA-OFDM. Because of peak to average power ratio (PAPR), the polar coded SCMA-OCDM based on CS_SLM is compared with clipping and filtering (CAF) method, about 2.08 dB receiver sensitivity gain is obtained when BER is lower than 10-5. The polar coded SCMA-OCDM based on CS_SLM also takes security into the consideration, due to the downlink broadcasting of PON. It can be a promising candidate for the next generation PONs.

Enhanced ABLO-OFDM performance by using composite multi-mode index modulation in IM/DD systems

In intensity modulation direct detection (IM/DD) systems, an adaptively biased layered optical orthogonal frequency division multiplexing (ABLO-OFDM) scheme is proposed based on composite multi-mode index modulation (CMM-IM). The ABLO-OFDM has a simple structure, easy demodulation, low complexity, and effectively reduces the peak-to-average power ratio (PAPR). Since CMM-IM extends the index to the constellation domain, it increases the number of index bits to further improve the spectral efficiency (SE). By dynamically adjusting the number of activated subcarriers and the number of layers, various signal power can be achieved to enhance system flexibility and reliability. The system performance of four schemes is compared and analyzed in IM/DD systems. The result shows that, for the same SE, CMM-ABLO (4,3) achieves a 3 dB receiver sensitivity gain compared with CMM-ABLO (8,2). When L is 3, four schemes can transmit over about 50 km single-mode fiber under the soft decision forward error correction (SD-FEC) threshold. When L is 1 and the sample rate is less than 20 GSa/s, both CMM-ABLO (4,2) and CMM-ABLO (4,3) can achieve error-free transmission. Moreover, as the number of layers increases, PAPR decreases and it reaches a maximum reduction of 9.6 dB.

Radiomics machine learning algorithm facilitates detection of small pancreatic neuroendocrine tumors on CT

PurposeThe purpose of this study was to develop a radiomics-based algorithm to identify small pancreatic neuroendocrine tumors (PanNETs) on CT and evaluate its robustness across manual and automated segmentations, exploring the feasibility of automated screening. Materials and methodsPatients with pathologically confirmed T1 stage PanNETs and healthy controls undergoing dual-phase CT imaging were retrospectively identified. Manual segmentation of pancreas and tumors was performed, then automated pancreatic segmentations were generated using a pretrained neural network. A total of 1223 radiomics features were independently extracted from both segmentation volumes, in the arterial and venous phases separately. Ten final features were selected to train classifiers to identify PanNETs and controls. The cohort was divided into training and testing sets, and performance of classifiers was assessed using area under the receiver operator characteristic curve (AUC), specificity and sensitivity, and compared against two radiologists blinded to the diagnoses. ResultsA total of 135 patients with 142 PanNETs, and 135 healthy controls were included. There were 168 women and 102 men, with a mean age of 55.4 ± 11.6 (standard deviation) years (range: 20–85 years). Median PanNET size was 1.3 cm (Q1, 1.0; Q3, 1.5; range: 0.5–1.9). The arterial phase LightGBM model achieved the best performance in the test set, with 90 % sensitivity (95 % confidence interval [CI]: 80–98), 76 % specificity (95 % CI: 62–88) and an AUC of 0.87 (95 % CI: 0.79–0.94). Using features from the automated segmentations, this model achieved an AUC of 0.86 (95 % CI: 0.79–0.93). In comparison, the two radiologists achieved a mean 50 % sensitivity and 100 % specificity using arterial phase CT images. ConclusionRadiomics features identify small PanNETs, with stable performance when extracted using automated segmentations. These models demonstrate high sensitivity, complementing the high specificity of radiologists, and could serve as opportunistic screeners.

A secure scheme based on polar-coded and 3D mixed domain scrambling in W-band MMW-RoF system

With the development of 6G network, the issue of physical layer security in optical fiber communication is becoming more and more significant. In this paper, a polar-coded encryption and 3D mixed domain scrambling secure scheme in W-band millimeter-wave radio-over-fiber (MMW-RoF) system is proposed. The keys are divided into the shared key and the dynamic key, and the shared key is used for constellation-level encryption and 3D mixed domain scrambling with 3D cat mapping, the dynamic key is used for polar code encryption. After RoF system transmission, the scheme can achieve a large key space of 10453, which is powerful enough to resist brute-force. Because the key is randomly selected in the codebook, this encryption scheme has the effect of resisting chosen-plaintext attacks. In terms of reliability, compared to traditional polar-OFDM and 3D QAM polar-OFDM, this scheme can achieve ∼0.4 dB and ∼0.45 dB gains in receiver sensitivity, respectively. So, the proposed scheme has good security performance and reliability performance, which has a significant potential for application in future optical networks.

Diagnostic performance of MRI-based radiomics models using machine learning approaches for the triple classification of parotid tumors

Rationale and objectivesPreoperative differentiation of malignant tumors (MT), pleomorphic adenomas (PA), and other benign tumors of the parotid gland is critical to clinical strategy, this study aimed to develop and validate a T2-weighted image (T2WI) based radiomics model through machine learning approaches for the triple classification of parotid gland tumors. Materials and methodsWe retrospectively enrolled 147 patients from January 2010 to July 2022. T2WIs were used to extract radiomics features. Max-Relevance and Min-Redundancy (mRMR) and Extreme Gradient Boosting (XGBoost) algorithms were used to select features. Using a 5-fold cross-validation strategy, radiomics models were constructed using a Support Vector Machine (SVM), Logistic Regression (LR), and k-Nearest Neighbor (KNN) for the triple classification of parotid tumors. The three models were evaluated and compared using the receiver operator characteristic (ROC) curve, sensitivity, specificity, and accuracy. ResultsA total of 1057 radiomics features were extracted, and 8 features were selected to developed the radiomics model, including First-order Median, First-order Skewness, First-order Minimum, Original_shape_Flatness, Glcm Inverse Variance, Glcm Inverse Variance, Glszm Low Gray Level Zone Emphasis, and Glszm Small Area Low Gray Level Emphasis. The mean area under the curves (AUCs) for the radiomics models in training and validation sets through LR, SVM and KNN were 0.85 and 0.80, 0.85 and 0.80 and 0.83 and 0.79, respectively. ConclusionThe T2WI-based radiomics models through LR, SVM and KNN demonstrated good performance in the triple classification of parotid tumors.

Concurrent performance and security enhancement of ultrahigh-order DSM signals via null subcarriers.

In this paper, we propose leveraging null subcarriers in discrete multi-tone modulation (DMT) to process the DMT signal in both time and frequency domains. Additionally, we employ discrete memory enhanced chaos (DMEC) to scramble the signal in the frequency domain, thereby achieving physical layer signal encryption while ensuring a more uniform power distribution in the time-domain waveform. In our experimental demonstration, we achieved high-security transmission of a DSM-based 65536-QAM signal at a data rate of 16.01 Gb/s over a 25 km single-mode fiber (SMF) in an intensity-modulation direct-detection (IMDD) system. Additionally, in the transmission experiments for 13684-QAM and 65536-QAM signals, the proposed method demonstrated a receiver sensitivity gain of over 0.5 dB compared to the traditional DSM-based ultrahigh-order transmission.

Theoretical probability distribution model and reduction techniques based on an interleaved DFT spread for PAPR in a digital sub-carrier multiplexing system.

This paper presents a theoretical probability distribution model for peak-to-average power ratio (PAPR) in the digital sub-carrier multiplexing (DSCM) system, which has not previously been proposed in the literature. To reduce PAPR, an interleaved discrete Fourier transform spread DSCM (I-DFT-S-DSCM) scheme is proposed, which introduces reversible correlations between subcarriers. To investigate the effectiveness of the proposed schemes, a 64-GBaud 16 quadrature amplitude modulation (16-QAM) DSCM system with 4, 8, and 16 sub-carriers was constructed. In the digital domain, the results demonstrate that the proposed theoretical PAPR probability distribution model exhibits mean squared errors (MSE) below 10-5 for the observed and model-predicted complementary cumulative distribution functions (CCDF) in both DSCM and I-DFT-S-DSCM schemes. Regarding PAPR reduction, the I-DFT-S-DSCM scheme demonstrated a reduction in PAPR of up to 1.44 dB compared to the conventional DSCM scheme. To further investigate the impact of PAPR on the bit error rate (BER) performance of the DSCM system, the I-DFT-S-DSCM scheme is implemented with 8 subcarriers transmitted over a 100-km standard single-mode fiber (SSMF). A comparative analysis with DSCM indicates that I-DFT-S-DSCM achieves a PAPR reduction of approximately 1.1 dB and improves receiver sensitivity by approximately 0.7 dB at a 7% hard-decision forward error correction (HD-FEC) threshold, in 100-km single-mode fiber SSMF transmissions.

A Survey of Visible-Light-Communication-Based Indoor Positioning Systems.

There is a growing demand for indoor positioning systems (IPSs) in a wide range of applications. However, traditional solutions such as GPS face many technical challenges. In recent years, a promising alternative has been emerging, the visible light communication (VLC)-based IPS, which offers a combination of high accuracy, low cost, and energy efficiency. This article presents a comprehensive review of VLC-based IPSs, providing a tutorial-like overview of the system. It begins by comparing various positioning systems and providing background information on their inherent limitations. Experimental results have demonstrated that VLC-based systems can achieve localization accuracy to within 10 cm in controlled environments. The mechanisms of VLC-based IPSs are then discussed, including a comprehensive examination of their performance metrics and underlying assumptions. The complexity, operating range, and efficiency of VLC-based IPSs are examined by analyzing factors such as channel modeling, signal processing, and localization algorithms. To optimize VLC-based IPSs, various strategies are explored, including the design of efficient modulation schemes, the development of advanced encoding and decoding algorithms, the implementation of adaptive power control, and the application of state-of-the-art localization algorithms. In addition, system parameters are carefully examined. These include LED placement, receiver sensitivity, and transmit power. Their impact on energy efficiency and localization accuracy is highlighted. Altogether, this paper serves as a comprehensive guide to VLC IPSs, providing in-depth insights into their vast potential and the challenges that they present.

A bidirectional free space optical link for last-mile terrestrial access links employing a novel wavelength shift keying technique

In this study, we propose a novel wavelength shift keying (WSK) technique that is combined with the conventional intensity modulation scheme for the transmission of point-to-point bidirectional data at the rate of 10 Gbps in each direction. We observe that WSK technique has not been investigated for implementation in point-to-point free space optical (FSO) links. Therefore, to the best of our knowledge, our study is the first one to perform this investigation. Our proposed link uses WSK in the downlink direction while we re-use the optical carriers for the transmission of uplink data. The use of WSK in the downlink direction enables us to perform balanced detection at the receiver, resulting in 3 dB improvement in receiver sensitivity compared to simple direct detection. We present bit error rate (BER) results for the signals transmitted in both the directions under different turbulence conditions and FSO link lengths. It was observed that the downlink signals generally perform better compared to the uplink due to the use of balanced detection and higher intensity fluctuations induced over the re-used optical carrier transmitted in the uplink direction.Please check and confirm that all the author names (given name, family name) and initials are correctly identified. The author names and initials are CORRECT.

Demonstration of an 8-Gbit/s quadrature-phase-shift-keying coherent underwater wireless optical communication link using coherent heterodyne detection under scattering conditions.

In this paper, we experimentally demonstrate an 8-Gbit/s quadrature-phase-shift-keying (QPSK) coherent underwater wireless optical communication (UWOC) link under scattering conditions at 532 nm. At the transmitter, we generate the 532-nm QPSK signal using second-harmonic generation (SHG), where the 1064-nm signal modulated with four phase levels of an 8-phase-shift-keying (8-PSK) format is phase doubled to produce the 532-nm QPSK signal. To enhance the receiver sensitivity, we utilize a local oscillator (LO) at the receiver from an independent laser source. The received QPSK data beam is mixed with the independent LO for coherent heterodyne detection. Results show that the bit error rates (BERs) of the received QPSK signal can reach below the 7% forward error correction (FEC) limit under turbid water with attenuation lengths (γL) up to 7.4 and 6.1 for 2- and 8-Gbit/s QPSK, respectively. The corresponding receiver sensitivities are -34.0 and -28.4 dBm for 2- and 8-Gbit/s QPSK, respectively.

The association between potential predictors and death of patients during the COVID-19 pandemic in Shiraz: a hierarchical multiple regression analysis

IntroductionIdentifying clinical factors that increase the risk of mortality in COVID-19 patients is crucial. This enables targeted screening, optimizing treatment, and prevention of severe complications, ultimately reducing death rates. This study aimed to develop prediction models for the death of patients (i.e., survival or death) during the COVID-19 pandemic in Shiraz, exploring the main influencing factors.MethodWe conducted a retrospective cohort study using hospital-based records of 1030 individuals diagnosed with COVID-19, who were hospitalized for treatment between March 21, 2021, and March 21, 2022, in Shiraz, Iran. Variables related to the final outcome were selected based on criteria and univariate logistic regression. Hierarchical multiple logistic regression and classification and regression tree (CART) models were utilized to explore the relationships between potential influencing factors and the final outcome. Additionally, methods were employed to identify the high-risk population for increased mortality rates during COVID-19. Finally, accuracy was evaluated the performance of the models, with the area under the receiver operator characteristic curve(AUC), sensitivity, and specificity metrics.ResultsIn this study, 558 (54.2%) individuals infected with COVID-19 died. The final model showed that the type of medicine antiviral (OR: 11.10, p = 0.038) than reference (antiviral and corticosteroid), and discharge oxygen saturation(O2) (OR: 1.10, p < 0.001) had a positive association with the chance of survival, but other variables were not considered as predictive variables. Predictive models for the final outcome(death) achieved accuracies ranging from 81 to 87% for hierarchical multiple logistic regression and from 87 to 94% for the CART model. Therefore, the CART model performed better than the hirerical multiple logistic regression model.ConclusionThese findings firstly elucidate the incidence and associated factors of the outcome (death) among patients in Shiraz, Iran. Furthermore, we demonstrated that antiviral medication alone (without corticosteroids) and high O2 increase the survival chances of COVID patients.

Joint constellation shaping optical modulation scheme based on a pair of common-bottomed trigonal cones.

A joint constellation shaping (JCS) three-dimensional (3D) 16-ary modulation scheme constructed with a pair of common-bottomed trigonal cones (CBTC) as primitives is proposed. Compared to the 3D traditional constellation (TC) and the 3D geometric constellation shaping (GS) structure previously proposed by our group (GGS), the constellation figure of merit (CFM) is improved by 0.3906 and 0.0097, respectively. Meanwhile, probabilistic shaping (PS) is employed to optimize the 3D-CBTC-16CAP constellation structure for the second time to enhance the CFM of the constellation further. Compared to the 3D-CBTC-16CAP, after PS the 3D-JCS-16CAP has a CFM improvement of 0.5014. Experiments are carried out to transmit the signals across a 2 km seven-core fiber. At the bit error rate (BER) threshold ∼3.8 × 10-3, the 3D-CBTC-16CAP scheme demonstrates an improvement in the receiver sensitivity by 0.76 and 0.39 dB compared with 3D-TC-16CAP and 3D-GGS-16CAP. In addition, the transmission effect of the signals after joint PS is verified. Experiments show that the proposed 3D-JCS-16CAP scheme has the most significant enhancement effect when used in conjunction with PS, and the receiver sensitivity is improved by about 0.97 and 0.34 dB compared with the 3D-JTC-16CAP (3D-TC-16CAP signal after joint PS) and 3D-JGGS-16CAP (3D-GGS-16CAP signal after the joint PS).

Prospective validation of a preoperative scoring system for difficult laparoscopy cholecystectomy.

Difficult laparoscopic cholecystectomy (LC) is defined by its surgical outcomes, including operative time, conversion to open surgery, bile duct and/or vascular injury. Difficult LC can be graded based on intraoperative findings. The main objective of this study is to apply and validate the reliability of their proposed risk score to predict the operative difficulty of an LC, based on their own validated intraoperative scale. Single-center prospective cohort study from 01/2020-12-2023. 367 patients > 18years who underwent LC were included. The preoperative risk scale and intraoperative grading system were registered. Surgical outcomes were determined. Predictive accuracy was evaluated by the Receiver Operator Characteristic curve, sensitivity, specificity, positive, and negative predictive values, and Youden's Index (J). Patients' mean age was 44.1 ± 15.3years. According to the risk score, 39.5% LC were "low" risk difficulty, 49.3% were "medium" risk, and 11.2% were "high" risk difficult LC. Based on the intraoperative grading system, 31.9% were difficult LC (Nassar grades 3-4) and 68.1% were easy LC (Nassar grades 1-2). There was a statistically significant correlation (0.428, p < 0.05) between the preoperative risk score and the intraoperative grading system. The AUC for the preoperative risk score scale and intraoperative difficult LC was 0.735 (95% CI 0.687-0.779) (J: 0.34). A preoperative risk score > 1.5 had an 83.7% sensitivity and a 50.8% specificity for intraoperative difficult LC. A predictive preoperative score for difficult LC and a routine collection of the intraoperative difficulty should be implemented to improve surgical outcomes and surgical planning.

All-optical wavelength reuse for meter reading application using EDFA saturation and DFB laser

The experiment utilizes the all-optical wavelength reuse for the realization of a cheaper meter reading approach. We demonstrate the all- optical wavelength reuse approach while exploiting a holding beam and the gain saturation of the erbium doped fiber amplifier (EDFA). A 10 Gb/s data is used to modulate a distributed feedback laser (DFB) and is transmitted downstream over 50 km. The saturated EDFA lowered the downstream data’s extinction ratio (ER) from 9.678 dB to 0.701 dB which is significant for both wavelength reuse and data rewrite for upstream transmission of meter reading as it facilitates the direct reuse of the downstream carrier without the addition of another electrical eraser for meter reading application. The variation of ER and the corresponding Peak to Peak power with EDFA input power for a 1550 nm 10 Gb/s DFB laser was demonstrated by Changing the bias current while maintaining the modulation voltage at 0.5 V allowed the input power into the EDFA to be adjusted from −7.278 dBm to 1.079 dBm. The performance analysis for upstream and downstream transmission was done and the receiver sensitivities determined at BER 10−9. The various eye diagrams were also analyzed for back-to-back (B2B) and 50 km upstream link and downstream link transmissions. This work is crucial for offering an all-optical wavelength reuse option for electrical meter reading application. In addition, the technique is all-optical and can therefore be able to support ultrafast systems with higher formats of modulation while ensuring efficiency in power.