Single Intensity Modulator Research Articles

Reconfigurable flexible PON downlink by using a wavelength selective switch and single intensity modulator

A reconfigurable passive optical network (PON) downlink has been experimentally demonstrated. A multi-carrier signal is generated in the digital domain and converted to an optical signal by a Mach-Zehnder intensity modulator. A wavelength selective switch (WSS) demultiplexes the sub-carriers for a distribution network. Each sub-carrier signal is a duo-binary filtered binary phase shift keying and directly detected at the receiver side. By changing the sub-carrier allocation and WSS port setting, the PON network can be easily reconfigured without changing the hardware configuration. The maximum capacity of 75-Gb/s with 10-km transmission and 128-way split has been achieved.

Dual electro-optic comb spectroscopy using a single pseudo-randomly driven modulator.

We present a dual-comb scheme based on a single intensity modulator driven by inexpensive board-level pseudo-random bit sequence generators. The result is a simplified architecture that exhibits a long mutual coherence time (up to 50 s) with no need of stabilization feedback loops or self-correction algorithms. Unlike approaches that employ ultrafast arbitrary waveform generators, our scheme makes it possible to produce long interferograms in the time domain, reducing the difference in the line spacing of the combs even below the hertz level. In order to check the system accuracy, we report two spectroscopic measurements with a frequency sampling of 140 MHz. All these results are analyzed and discussed to evaluate the potential of our scheme to implement a field-deployable dual-comb generator.

Wide Optical Frequency Comb System Based on Single Intensity Modulator

Wide Optical Frequency Comb System Based on Single Intensity Modulator

Simple 2.5 GHz time-bin quantum key distribution

We present a 2.5 GHz quantum key distribution setup with the emphasis on a simple experimental realization. It features a three-state time-bin protocol based on a pulsed diode laser and a single intensity modulator. Implementing an efficient one-decoy scheme and finite-key analysis, we achieve record breaking secret key rates of 1.5 kbps over 200 km of standard optical fibers.

Pre-coding assisted generation of a frequency quadrupled optical vector D-band millimeter wave with one Mach-Zehnder modulator.

We propose QPSK millimeter-wave (mm-wave) vector signal generation for D-band based on balanced precoding-assisted photonic frequency quadrupling technology employing a single intensity modulator without an optical filter. The intensity MZM is driven by a balanced pre-coding 37-GHz QPSK RF signal. The modulated optical subcarriers are directly sent into the single ended photodiode to generate 148-GHz QPSK vector signal. We experimentally demonstrate 1-Gbaud 148-GHz QPSK mm-wave vector signal generation, and investigate the bit-error-rate (BER) performance of the vector signals at 148-GHz. The experimental results show that the BER value can be achieved as low as 1.448 × 10-3 when the optical power into photodiode is 8.8dBm. To the best of our knowledge, it is the first time to realize the frequency-quadrupling vector mm-wave signal generation at D-band based on only one MZM without an optical filter.

Microwave Frequency Quadrupling Based on Distributed Feedback Laser and a Single Intensity Modulator

ABSTRACTIn this article, we have proposed and experimentally demonstrated a directly modulated distributed feedback laser (DFB-LD) to generate microwave and millimeter-wave signals. The proposed scheme uses DFB-LD and intensity modulator (IM) biased at null point. A radio frequency (RF) signal from a signal generator is split into two branches and one branch directly modulates the DFB-LD, while the other branch drives the IM. Two second-order sidebands separated by four times the frequency of the input RF signal are generated. Experimental results indicated that we can generate a four-fold microwave signal with a good optical signal to noise ratio.

Optical frequency comb generation via an intensity modulator in a Sagnac loop

We propose a simple optical frequency comb generator with a Nyquist temporal waveform that uses an intensity modulator in a Sagnac loop. By properly adjusting the polarization of the output from the Sagnac loop, a quasi-rectangular-shaped five-tone optical frequency comb with a Nyquist temporal waveform is theoretically and experimentally demonstrated. Previous work has shown that it is impossible to generate Nyquist pulses with more than three comb lines using a single intensity modulator. In our scheme, only one radio-frequency signal with relatively low power and only one direct-current voltage is needed, which effectively increases the system reliability and decreases the system complexity and cost.

Investigation on Nyquist pulse generation by optical frequency comb

Compared with OFDM, Nyquist signal transmission has several unique advantages, such as lower receiver complexity, lower receiver bandwidths, and lower peak-to-average power ratios, which give better performances under fiber nonlinear impairments. Since the sinc-shaped waveforms in the time domain correspond to a rectangular spectrum in the frequency domain, the Nyquist pulses can also be obtained directly from the generation of a flat frequency comb with electro-optic modulators. In this paper, a complete theoretical analysis of Nyquist pulse generation with 3 comb lines generated with a single intensity modulator is developed. It is proved that both the amplitude and phase of the sidebands in the optical frequency comb are important for generation of Nyquist pulses. Theoretically, it is found that it is impossible to generate Nyquist pulses with more than 3 comb lines using a single intensity modulator even if 5 flat comb lines are realized. A Nyquist pulse can be generated with 9 comb lines by two cascaded intensity modulators, but the sum of the phase shift caused by the two DC voltages of the intensity modulators must be π.

Simultaneous Generation of Independent Wired and Wireless Services Using a Single Modulator in Millimeter-Wave-Band Radio-Over-Fiber Systems

We experimentally demonstrated a novel radio-over-fiber scheme to simultaneously obtain independent wired and wireless signals by using only a single intensity modulator. The optical 40- or 60-GHz millimeter-wave (mm-wave) carriers are generated by means of subcarrier-multiplexing techniques to carry 2.5-Gb/s wireless signals while 10-Gb/s wired signals are imposed on the original optical carrier via regular intensity modulation. The signals with dual services are successfully transmitted over 20-km single-mode fiber (SMF-28) with less than 1.5-dB power penalty.

Direct generation of subpicosecond chirp-free pulses at 10 GHz from a nonpolarization maintaining actively mode-locked fiber ring laser

0.7-1.3 ps highly stable, transform-limited, sech/sup 2/-shaped pulses at 10 GHz in the 1536-1569 nm wavelength region from a nonpolarization maintaining (PM), single intensity modulator, actively and harmonically mode-locked fiber ring laser have been directly generated. Little degradation of long-term stability of the laser operation was observed due to the non-PM nature of the laser cavity.