True linearized intensity modulation for photonic analog to digital conversion using an injection-locked mode-locked laser

A true linearized interferometric intensity modulator for pulsed light has been proposed and experimentally presented in this thesis. This has been achieved by introducing a mode-locked laser into one of the arms of a Mach-Zehnder interferometer and injection-locking it to the input light (which is pulsed and periodic). By modulating the injection-locked laser, and combining its output light with the light from the other arm of interferometer in quadrature, one can achieve true linearized intensity modulator. This linearity comes from the arcsine phase response of the injection-locked mode-locked laser (as suggested by steady-state solution of Adler\u27s equation) when it is being modulated. Mode-locked lasers are fabricated using a novel AlGaInAs-InP material system. By using the BCB for planarization and minimizing the metal pad size and directly modulating the laser, we have achieved very effective fundamental hybrid mode-locking at the repetition rate of ~ 23 GHz. This laser also provided the short pulses of 860 fs and 280 fs timing jitter integrated from 1 Hz- 100 MHz. The linearized intensity modulator has been built by using two identical two-section mode-locked lasers with the same length, one as the slave laser in one of the arms of the Mach-Zehnder interferometer injection-locked to the other one as the master which is the input light to the modulator. A low V? of 8.5 mV is achieved from this modulator. Also the current of the gain section or the voltage of the saturable absorber section of the slave laser has been used to apply the modulation signal. A spur free dynamic range of 70 dB.Hz2/3 is achieved when modulating the modulator through the saturable absorber. Modulating the saturable absorber provides a reduced third-order intermodulation tone with respect to modulating the gain. This is simply because of the unwanted amplitude modulation created when modulating the gain section current. Finally an improved design is proposed and demonstrated to improve the modulator performance. This is achieved by introducing a third section to the laser. Using the impurity free vacancy disordering technique the photoluminescence peak of this section is blue-shifted selectively and therefore there would not be any absorption in that passive section. By applying the modulation signal to this passive section rather than applying it to the gain section or saturable absorber section, the amplitude and phase modulation could be decoupled. The experimental results have presented here and an almost six-fold reduction in V? and 5 dB improvement in spur free dynamic range have been achieved. The proposed and demonstrated configuration as an analog optical link has the potential to increase the performance and resolution of photonic analog-to-digital converters

Towards Highly Linear Intensity Modulator For High Resolution Photonic Adcs Using A Three -Section Mode-Locked Laser

A novel highly linear intensity modulator is proposed using an injection-locked threesection mode-locked laser. Modulating the passive section of the mode-locked laser reduces Vπ to 1.1 mV and should greatly increase SFDR. © OSA 2015

Towards Highly Linear Intensity Modulator For High Resolution Photonic Adcs Using A Three-Section Mode-Locked Laser

A novel highly linear intensity modulator is proposed using an injection-locked three-section mode-locked laser. Modulating the passive section of the mode-locked laser reduces Vπ to 1.1 mV and should greatly increase SFDR

Monolithic Three-Section Injection-Locked Laser For Optical Oversampled Analog-To-Digital Conversion

A novel linear interferometric intensity modulator is demonstrated with an extremely low Vπ of 1.1 mV and a SFDR of 75 dB.Hz2/3. This is achieved by modulating the passive section of the injection-locked mode-locked laser

Injection-Locked Semiconductor Laser-Based Frequency Comb For Modulation Applications In Rf Analog Photonics

A linearized intensity modulator for periodic and pulsed light is proposed and demonstrated. The free carrier plasma effect has been used to modulate the refractive index of the phase section of a three-section mode-locked laser. If injection locked, the modulation induces an arcsine phase response on the three-section mode-locked laser. By introducing this mode-locked laser into a Mach-Zehnder interferometer biased at quadrature, one can realize a true linear intensity modulation. This novel laser suppresses any unwanted amplitude modulation and increases the performance of the linearized intensity modulator. Experimental results have provided a record low static Iπ of 0.39 mA and a spur-free dynamic range of 75 dB.Hz2/3

A Linearized Intensity Modulator For Analog Optical Links Using A Three-Section Mode-Locked Laser

A true linearized intensity modulator for pulsed light is demonstrated using an injection-locked three-section mode-locked laser. A low Vπ of 1.1 mV and SFDR of 75 dB.Hz2/3 are achieved by modulating the phase section

A Novel Intensity Modulator For Photonic Adcs Using An Injection-Locked Mode-Locked Laser

A novel intensity modulator for pulsed light is proposed and demonstrated here for the first time. This has been realized by introducing an injection-locked AlGaInAs mode-locked laser into one arm of a Mach-Zehnder interferometer. © 2014 OSA

Direct Rf Synchronization Of A 22 Ghz Monolithic Alingaas Quantum Well Laser With Sub-Picosecond Pulse Generation

A 22 GHz AlInGaAs two-section mode-locked laser is presented here. 860 fs optical pulses with timing jitter of 280 fs (1 Hz-100 MHz) are generated by direct RF modulation of the saturable absorber. © 2012 IEEE

High-Q Transfer In Nonlinearly Coupled Mode-Locked Semiconductor Lasers

A novel four-wave mixing-based injection locking method was demonstrated earlier, whereby the optical and RF stability of a mode-locked high-Q ring laser is successfully transferred to an orthogonally coupled colliding pulse mode-locked (CPM) laser. Four-wave mixing in the common monolithically integrated saturable absorber is used to couple the crossed laser cavities, which is confirmed by the reduction in RF noise level and by the optical linewidth reduction of the lasing modes of the slave CPM laser. The four-wave mixing process was then further investigated and experimentally shown to be the primary mechanism responsible for the locking and stabilization of the slave laser. This paper discusses the above four-wave mixing technique in detail and presents an improved design by employing optical subharmonic hybrid mode-locking and by decreasing the losses inside the master ring cavity. The resulting higher stability of the master laser translates into further improvement in the RF and optical linewidths of the injection locked slave CPM laser. These results demonstrate the effectiveness of the novel method for all on-chip stability transfer in the forthcoming all monolithic optical pulse source systems

All Optical Stabilization Of A Monolithic Quantum Dot Based Cpm Laser Via Four-Wave Mixing

We investigate and confirm a four-wave mixing (FWM) process as the primary mechanism responsible for locking and stabilization of a previously reported novel quantum dot based monolithically coupled colliding pulse mode-locked (CPM) laser. In the previous letter, a high-Q passively mode-locked ring laser is used to injection lock an orthogonally coupled passively mode-locked CPM slave laser via FWM in the common saturable absorber. In this letter, we setup an experiment to verify the FWM process, whereby the external ring laser is operated unidirectionally while simultaneously analyzing the amplified spontaneous emission from the other facet of the ring laser. The emission is found to contain CPM light only in the presence of injection locking proving the FWM process. Other linear scattering effects are also investigated and shown to be negligible in the orthogonal waveguide configuration. © 1989-2012 IEEE