Lithium Niobate Intensity Modulators Research Articles

Simulation of a flat optical frequency comb using a single-drive multi-RF Mach–Zehnder modulator in a cascaded intensity modulator chain

We proposed a scheme based on two cascaded lithium niobate intensity modulators to generate an optical frequency comb with very high flatness. Single-drive multi-RF waveforms are used for driving the first intensity modulator, and 9 lines within 1dB power variation can be obtained. When cascading with another intensity modulator, by specially adjusting the DC bias and the drive amplitudes of the RF signals of the two intensity modulators, 27 or 45 comb lines with a spectral power variation about 1dB are obtained. The scheme is relatively simple and adjustable, and the frequency interval of the OFC varies with microwave frequency applied on modulators.

Investigation of optical clock division and demultiplexing based on a commercial lithium niobate‐intensity modulator

AbstractWe demonstrate and investigate a simple technique to realize multichannel optical clock division by using a commercial lithium niobate‐intensity modulator (LN‐IM). Optical clock division is achieved by controlling the driving and dc bias voltage of the LN‐IM. 20‐ to 10‐GHz optical clock division experiments of both single and double channel are implemented to verify the performance of the proposed optical clock divider. The phase noise of the extracted 10‐GHz optical clock is less than 95 dBc/Hz. The other function of this technique, demultiplexing of optical time division multiplexing (OTDM) signal is also demonstrated experimentally. The 20‐Gb/s PRBS OTDM signal is successfully demultiplexed to two 10 Gb/s with high quality. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:94–99, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26477

Optical regenerative NRZ to RZ format conversion based on cascaded lithium niobate modulators

Optical regenerative nonreturn-to-zero (NRZ) to return-to-zero (RZ) format conversion using a lithium niobate phase modulator and a lithium niobate intensity modulator is proposed and demonstrated. The key advantage of the proposed format converter is that the converted RZ signal has a very small pulse width, which can be multiplexed to a higher bit rate using optical time division multiplexing technology. The operation can greatly reduce the timing jitter of the degraded NRZ signal due to the regenerative property of the proposed scheme. Besides, the format converter can also support multi-channel operation. An experiment is performed with the feasibility of the scheme demonstrated.

2-$\mu$m Mode-Locked Semiconductor Disk Laser Synchronously Pumped Using an Amplified Diode Laser

We report a mode-locked antimonide-based semiconductor disk laser operating at 2 $\mu$ m, synchronously pumped with a pulsed source incorporating a 1.57- $\mu$ m diode laser, a lithium niobate intensity modulator, and an erbium-doped fiber amplifier. The method for producing the pump signal utilizes commercially available telecom components and allows for convenient selection of the mode-locking harmonics. When compared with configurations based on mode-locked pump sources, the generation of pump pulses using amplitude modulation and digital data technology is simple and offers the possibility to actively lock the optical pulses to a stable clock.

Laser Transmitter for Undersea Communications Using Third-Harmonic Generation of Fiber-Laser System at 1.5 $\mu$m

We report a viable laser transmitter for free-space undersea communications. An all-fiber, picosecond, Watt-level master-oscillator-power-amplifier (MOPA) system at 1.5 mum based on rapid amplification of mode-locked pulses in heavily Er:Yb codoped phosphate fiber is combined with fiber pigtailed lithium niobate intensity modulator (pulse picker), to construct a fully integrated eye-safe transmitter operating at 65-Mb/s data rate, that can be used in intermediate-range (few kilometers) atmospheric communication links. For undersea use, the output of the MOPA system is frequency-tripled into the blue-green transparency window of ocean water. The wavelength conversion occurs in a simple single-pass setup utilizing a sequence of two periodically poled lithium niobate crystals, both of which are operated at room temperature. The conversion efficiency from fundamental to third harmonic reached 14% and resulted in generation of 140 mW of average power at 518 nm. The conversion efficiency can be straightforwardly increased threefold using properly antireflection-coated optics in the free-space part of the setup, and the data rate can be scaled up into the gigabit-per-second range by using a faster mode-locked oscillator in the MOPA system.

Photonic serial-parallel conversion of high-speed OTDM data

We demonstrate full demultiplexing of a single 100-Gb/s optical time-division multiplexed data stream into eight parallel 12.5-Gb/s streams. This is performed using a photonic serial-to-parallel converter based on lithium niobate intensity modulators, and requires no nonlinear optical elements. Error-free operation is obtained for each of the eight output channels.