High-speed Modelocked Semiconductor Lasers And Applications In Coherent Photonic Systems

1.55-µm high-speed modelocked semiconductor lasers are theoretically and experimentally studied for various coherent photonic system applications. The modelocked semiconductor lasers (MSLs) are designed with high-speed (\u3e5 GHz) external cavity configurations utilizing monolithic two-section curved semiconductor optical amplifiers. By exploiting the saturable absorber section of the monolithic device, passive or hybrid mode-locking techniques are used to generate short optical pulses with broadband optical frequency combs. Laser frequency stability is improved by applying the Pound-Drever-Hall (PDH) frequency stabilization technique to the MSLs. The improved laser performance after the frequency stabilization (a frequency drifting of less than 350 MHz), is extensively studied with respect to the laser linewidth (~ 3 MHz), the relative intensity noise (RIN) (\u3c -150 dB/Hz), as well as the modal RIN (~ 3 dB reduction). MSL to MSL, and tunable laser to MSL synchronization is demonstrated by using a dual-mode injection technique and a modulation sideband injection technique, respectively. Dynamic locking behavior and locking bandwidth are experimentally and theoretically studied. Stable laser synchronization between two MSLs is demonstrated with an injection seed power on the order of a few microwatt. Several coherent heterodyne detections based on the synchronized MSL systems are demonstrated for applications in microwave photonic links and ultra-dense wavelength division multiplexing (UD-WDM) system. In addition, efficient coherent homodyne balanced receivers based on synchronized MSLs are developed and demonstrated for a spectrally phase-encoded optical CDMA (SPE-OCDMA) system

Coherent pulse detection and multi-channel coherent detection based on a single balanced homodyne receiver

The performance of coherent pulse detection (CPD) and multichannel coherent detection (MCCD) based on a single dual-balanced homodyne receiver was experimentally demonstrated using a grating-coupled hybridly mode-locked semiconductor laser. Compared with direct detection, a high coherent gain of over 10 dB, as well as an SNR improvement of over 5 dB, was obtained in both detection schemes. Our experimental results have confirmed that the coherent detection processes in CPD and MCCD are nearly the same based on a square-root LO power dependence. Nevertheless, the MCCD scheme has shown an advantage in a path-length error over the CPD scheme, revealing 2 similar to 3 dB improvement in sensitivities

Ultralow noise optical pulse generation in an actively mode-locked quantum-dot semiconductor laser

We report excellent noise performance of an external-cavity actively mode-locked laser based on quantum-dot gain medium. Optical pulse trains with less than 7.5 fs residual timing jitter (1 Hz to 10 MHz) for a 12.8 GHz harmonically mode-locked ring laser were obtained. This result represents, to our knowledge, the lowest residual jitter reported from actively mode-locked semiconductor lasers, and shows that quantum-dot mode-locked lasers are promising as sources of ultralow noise optical pulse trains

Optical Heterodyne Detection Based On Dual-Mode Injection Locking Of Modelocked Semiconductor Lasers

Optical heterodyne detection based on a novel injection locking technique is demonstrated using synchronized optical frequency comb sets from two independent modelocked semiconductor lasers. The measurement is performed with RZ coded 223-1 long 500 Mb/s PRBS

Demonstration Of Coherent Heterodyne Detection With Synchronized Mode-Locked Semiconductor Lasers For Secure Communication Application

We have demonstrated coherent heterodyne detection for an arrayed coherent receiver system based on synchronized modelocked semiconductor lasers. Dual-mode injection locking technique is employed to achieve excellent oscillator synchronization between two independent modelocked semiconductor laser systems

A Master Oscillator Power Amplifier System Based On External Cavity Mode-Locking Of A Quantum-Dot Twosection Diode Laser

We study ultrashort, high power pulse generation from a master oscillator power amplifier system based on an external cavity QD mode-locked two-section diode laser and a multilayer QD-SOA The compressed pulses are 1.2 psec in duration, with a pulse energy of 1.46 pJ, implying a peak power of 1.22 W. © 2005 IEEE

Demonstration Of Optical Heterodyne Detection Using A Modelocked Semiconductor Laser Broad-Band Coherent Probe System

The experimental results of optical heterodyne detection based on injection locking technique, using two independently modelocked semiconductor laser oscillators are presented. A signal-to-noise ratio of over 60dB/Hz has been achieved in a demultiplexed channel. © 2004 IEEE

Injection Locked Passively Modelocked Semiconductor Laser For Optical Heterodyne Detection Using A Single Axial Mode

The optical heterodyne detection for an extremely densely channelized coherent communication systems using phase coherent optical combs is demonstrated by using a passively modelocked semiconductor laser injection locked to a master laser oscillator. The single sideband noise of the heterodyne beat tone at 13.160 GHz was reduced to -123 dBc/Hz at 100 kHz offset from the carrier by exploiting the excellent noise rejection performance of a commercially available microwave bandpass filter. A signal-to-noise ratio of over 65 dB/Hz has been achieved in a single channel filtered from two analog RF signals detuned by only 200 MHz. These results show improved signal-to-noise ratio and superior crosstalk reduction between densely packed neighboring channels via electrical manipulation of the optical heterodyne detection signal

Relative Intensity Noise Characteristics In A Frequency Stabilized Modelocked Semiconductor Laser System

RIN characteristics in a frequency stabilized MSL were experimentally and theoretically investigated. Average RIN level of less than -150dB/Hz as well as Modal RIN reduction of approximately 3dB were obtained from the frequency stabilized MSL. © 2005 Optical Society of America