Simultaneous Generation of Multiband Signals Using External Cavity-Based Fabry–Perot Laser Diode

Nakarmi, Bikash,Pan, Shilong,Won, Yong Hyub Professional Technical Group on Microwace Theory a 2018 IEEE transactions on microwave theory and techniqu Vol.66 No.1

<P>Photonic generation of tunable microwave signal has gained the attention of many research communities. Various active components such as vertical-cavity surface-emitting laser diode, semiconductor optical amplifier, and Fabry–Perot laser diode have been used for generating microwave signals using different techniques including side mode injection, feedback injection, and frequency combs. In this paper, we propose and demonstrate a novel approach to generate millimeter wave, simultaneous microwave and millimeter wave, and microwave together with hopping of RF frequency using a single external beam. Furthermore, we demonstrate injecting multiple external beams in a spatial-mode Fabry–Perot laser diode (SMFP-LD) to generate simultaneous multiband signals with negative wavelength detuning. The generated signal ranges from microwave to terahertz. We inject four external beams in SMFP-LD to generate RF frequencies that lie in Ku-, K-, Ka-, V-bands and higher millimeter wave. The frequency of generated signals can be tuned from a few gigahertz to several terahertz. The effects of changing the dominant mode, injecting external beams to different side modes, wavelength and power stability of beating wavelengths, and harmonic generations are analyzed. The maximum linewidth of the generated RF signals with multiple input beams (up to 42.5 GHz) is found to be about 300 kHz.</P>

Microwave Frequency Generation, Switching, and Controlling Using Single-Mode FP-LDs

Nakarmi, Bikash,Chen, Hao,Won, Yong Hyub,Pan, Shilong IEEE 2018 Journal of Lightwave Technology Vol.36 No.19

<P>RF signal generation, switching, and reconfiguring are essential and important features for the rapidly developing microwave system, which are usually implemented using independent components or subsystems. In this paper, we propose and demonstrate an optical method to generate and switch the RF frequency at the stage of generation based on control input state using external cavity based single mode Fabry–Pérot laser diode. The RF frequency generation, switching, and controlling are based on the principle of injection locking with negative and positive wavelength detuning. In the proposed scheme, a single external beam is simultaneously used to control RF switching as well as to generate RF signal through optical heterodyning of injection locked beams. This eliminates the necessity of two separate external beams to switch and generate RF signal. Based on the logic state of the input control beam, the frequency of the generated RF signal can be changed to another RF frequency within a group of predefined RF bands. In a proof-of-concept experiment, a 2-Gbps, 16-bit nonreturn-to-zero control signal is applied to switch the frequency of the generated RF signal. We obtain the minimum signal to noise power ratio of more than 23 dB, the maximum linewidth of 165 kHz, and rising and falling times of less than 40 ps associated with the RF switching. The tunable range, RF frequency, and RF power variation of the generated RF signals are also observed. Moreover, using random control signals, random sequences of RF frequencies can be generated using the same experimental and hardware setup. Such reconfigurability and flexibility of our system to generate several random RF signals from the same framework enables application of the proposed method in several fields such as secure communication, encryption, and military applications.</P>

Realization of all-optical multi-logic functions and a digital adder with input beam power management for multi-input injection locking in a single-mode Fabry-Pérot laser diode.

Nakarmi, Bikash,Rakib-Uddin, M,Won, Yong Hyub Optical Society of America 2011 Optics express Vol.19 No.15

<P>We propose a novel idea for the suppression of the dominant mode of the single-mode Fabry-Pérot laser diode (SMFP-LD) to realize all-optical multi-logic functions and a digital adder. The basic principle of the proposed scheme is the power management of input beams to suppress the dominant mode of the SMFP-LD for multi-input injection locking. The proposed principle is explained and implemented to realize all-optical multi-logic functions and a digital adder at an input data rate of 10 Gbps. A clear eye opening with an extinction ratio of about 12 dB and a rising-falling time of less than 40 ps are observed at the outputs. The bit error rate (BER) performance is measured for all logic gates and half adder operation. We found there is no BER floor up to BER of 10(-12) and the maximum power penalty of about 1.2 dB at a BER of 10(-9).</P>

Short-pulse controlled optical switch using external cavity based single mode Fabry-P?rot laser diode.

Nakarmi, Bikash,Hoai, Tran Quoc,Won, Yong-Hyub,Zhang, Xuping Optical Society of America 2014 Optics express Vol.22 No.13

<P>We propose and demonstrate a novel scheme for short pulse controlled all-optical switch using external cavity based single mode Fabry- P?rot laser diode (SMFP-LD). The proposed scheme consists of control unit and switching unit as two essential blocks. The basic principle of the proposed scheme is the optical bistability property of SMFP-LD for the control unit and the suppression of the dominant beam of SMFP-LD with injection locking for the switching unit. We also present the analysis of hysteresis width and rising/falling time with change in wavelength detuning which helps to find the optimum wavelength detuning value and power of light beams at different stages of the proposed scheme that gives wide input dynamic power range, high ON/OFF contrast ratio, and low rising/falling time. Input data of 10 Gb/s Non Return to Zero (NRZ) signal is switched at output ports depending upon the control signal generated by the control unit, which comprises of optical SR latch. Output waveforms, clear eye diagrams with extinction ratio of about 11 dB, rising/falling time of about 30 ps and 40 ps, and bit error rate (BER) are measured to validate proposed scheme. No noise floor is observed at output ports up to BER of 10-(12) and the maximum power penalty recorded is about 1.7 dB at a BER of 10-(9) which shows good performance of the proposed short pulse controlled optical switch using SMFP-LDs.</P>

Realization of All-Optical Digital Comparator Using Single Mode Fabry–Pérot Laser Diodes

Nakarmi, B.,Rakib-Uddin, M.,Yong Hyub Won IEEE 2011 Journal of Lightwave Technology Vol.29 No.19

<P>A two-bit all-optical digital comparator using single mode Fabry-Pérot laser diodes (SMFP-LDs) at an input data rate of 10 Gbps is proposed and demonstrated. All-optical comparator is demonstrated using cascaded logic units which are based on injection locking, multi-input injection locking and supporting beam principles for suppressing the dominant mode of SMFP-LDs. Digital comparators are the key components for the decision making circuits, the integral part of the arithmetic and logical units of optical data processors. The output performance of the proposed all-optical comparator is verified with output waveform, rising-falling time, output eye diagram, and bit error rate (BER) at 10 Gbps input Non Return to Zero (NRZ) PRBS of 2<SUP>31</SUP>-1 signal. The rising/falling time of about 47 ps, clear output waveforms, and clear output eye diagram with an extinction ratio of about 12 dB are obtained. A maximum power penalty of 1.3 dB is measured at a BER of 10<SUP>-9</SUP>.</P>

Demonstration of All-Optical nand Gate Using Single-Mode Fabry–Pérot Laser Diode

Nakarmi, B,Rakib-Uddin, M,Hoai, T Q,Yong Hyub Won IEEE 2011 IEEE photonics technology letters Vol.23 No.4

<P>A novel, simple, and universal all-optical NAND gate using single-mode Fabry-Pérot laser diode (SMFP-LD) is demonstrated. The basic operating principle of the proposed NAND gate is the modulation of the dominant lasing mode of SMFP-LD by the injection of external beams. The dominant lasing mode gain is suppressed only when both input beams are high. As SMFP-LD is used to demonstrate the logic function, no additional beam is required as needed in the multimode Fabry-Pérot laser diode (MMFP-LD) schemes. The operating principle is explained and the experimental results are presented at 10 Gb/s input data. The logic function is realized with a clear eye opening and an extinction ratio of 14.6 dB with a rising and falling time of 38.3 and 67.1 ps, respectively.</P>

Injection With Negative Wavelength Detuning for Multispectrum Frequency Generation and Hopping Using SMFP-LD

Nakarmi, Bikash,Chen, Hao,Lee, Muyong,Won, Yong Hyub,Pan, Shilong IEEE 2017 IEEE photonics journal Vol.9 No.5

<P>We propose and demonstrate a novel method to generate multispectrum frequency and hopping from one frequency spectrum to another using a single external cavity based Fabry-Perot laser diode (FP-LD) subjected to a single optical injection with negative wavelength detuning. The external cavity based FP-LD has a single dominant mode, single-mode FP-LD (SMFP-LD), and hence the beating of the dominant mode and the injected beam, and the beating of the injected beam and the corresponding side mode of SMFP-LD are possible with a single optical injection. The generated frequency can be tuned to a wide range of GHz to several THz. Individual or simultaneous RF signals generation and hopping between microwave and millimeter wave spectrum are reported. The effect of the injected beam power on generating and hopping of RF frequency is analyzed in the case of negative wavelength detuning with the input beam injected on different modes of SMFP-LD. Also, the stability of beating wavelengths, power variations of beating wavelengths for an interval of 1 hour, and linewidth of RF signals are observed.</P>

Analysis of Hysteresis Width on Optical Bistability for the Realization of Optical SR Flip-Flop Using SMFP-LDs With Simultaneous Inverted and Non-Inverted Outputs

Nakarmi, B.,Hoai, T. Q.,Won, Y. H.,Xuping Zhang IEEE 2014 IEEE photonics journal Vol.6 No.3

<P>The width of hysteresis in optical bistability plays an important role on latching operation. The injected input optical power and wavelength detuning in single mode Fabry-Perot laser diode (SMFP-LD) are two parameters that can impact the width of hysteresis in bistability of dominant mode and injected mode. In this paper, we analyze the effect of wavelength detuning on width of the hysteresis loop, the dynamic power range for optical bistability, and the rising-falling time of output waveform. With this analysis, optical Set Reset flip-flop with simultaneous inverted and non-inverted output at the data rate of 8.5 Gb/s are obtained using SMFP-LDs. The principle is based on the optical bistability phenomena during injection-locking of the Fabry-Perot laser diode. The set and reset pulses are maintained in low power of about -14 and -6 dBm for the power effective configuration. The contrast ratios of more than 20 dB with simultaneous non-inverted and inverted output Q and Q are observed. Clear output spectrum domain results, waveforms, eye diagram with extinction ratio of more than 12 dB, a rising/falling time of about 40 ps, and bit error rate (BER) measurement without noise floor up to 10 <SUP>-12</SUP> are observed. The maximum power penalty is about 1.8 dB at BER of 10 <SUP>-9</SUP>.</P>

Central limit theorem for the variable bandwidth kernel density estimators

Janet Nakarmi,Hailin Sang 한국통계학회 2018 Journal of the Korean Statistical Society Vol.47 No.2

In this paper we study the ideal variable bandwidth kernel density estimator introduced by McKay (1993a, b) and Jones et al. (1994) and the plug-in practical version of the variable bandwidth kernel estimator with two sequences of bandwidths as in Giné and Sang (2013). Based on the bias and variance analysis of the ideal and plug-in variable bandwidth kernel density estimators, we study the central limit theorems for each of them. The simulation study confirms the central limit theorem and demonstrates the advantage of the plug-in variable bandwidth kernel method over the classical kernel method.

불필요한 소비는 미룹시다

L. 나카르미(Laxmi Nakarmi) 샘터사 1990 월간 샘터 Vol.21 No.10