M. Pantouvaki

A Monolithic MQW InP–InGaAsP-Based Optical Comb Generator

We report the first demonstration of a monolithic optical-frequency comb generator. The device is based on multisection quaternary/quaternary eight-quantum-well InP-InGaAsP material in a frequency-modulated (FM) laser design. The modulation is generated using quantum-confined Stark-effect phase-induced refractive index modulation to achieve fast modulation up to 24.4 GHz. The laser was fabricated using a single epitaxial growth step and quantum-well intermixing to realize low-loss phase adjustment and modulation sections. The output was quasicontinuous wave with intensity modulation at less than 20% for a total output power of 2 mW. The linewidth of each line was limited by the linewidth of the free running laser at an optimum of 25 MHz full-width at half-maximum. The comb generator produces a number of lines with a spacing exactly equal to the modulation frequency (or a multiple of it), differential phase noise between adjacent lines of -82 dBc/Hz at 1-kHz offset (modulation source-limited), and a potential comb spectrum width of up to 2 THz (15 nm), though the comb spectrum was not continuous across the full span.

Fast Tuneable InGaAsP DBR Laser Using Quantum-Confined Stark-Effect-Induced Refractive Index Change

We report a monolithically integrated InGaAsP DBR ridge waveguide laser that uses the quantum-confined Stark effect (QCSE) to achieve fast tuning response. The laser incorporates three sections: a forward-biased gain section, a reverse-biased phase section, and a reverse-biased DBR tuning section. The laser behavior is modeled using transmission matrix equations and tuning over ~8 nm is predicted. Devices were fabricated using post- growth shallow ion implantation to reduce the loss in the phase and DBR sections by quantum well intermixing. The lasing wavelength was measured while varying the reverse bias of the phase and DBR sections in the range 0 V to <-2.5 V. Tuning was noncontinuous over a ~7-nm-wavelength range, with a side-mode suppression ratio of ~20 dB. Coupled cavity effects due to the fabrication method used introduced discontinuities in tuning. The frequency modulation (FM) response was measured to be uniform within plusmn2 dB over the frequency range 10 MHz to 10 GHz, indicating that tuning times of 100 ps are possible.

10-Gb/s all-optical 2R regeneration using an MQW Fabry-Perot saturable absorber and a nonlinear fiber

An all-optical 2R regenerator that consists of an ion implanted InGaAsP multiple-quantum-well saturable absorber, a nonlinear fiber, and an optical filter is presented. Error-free 10-Gb/s transmission over 7000 km of standard fiber with an amplifier spacing of 80 km is demonstrated in a recirculating loop experiment.

Photonic synthesis of THz signals

In this paper we present a review of our work on photonic synthesis of high spectral purity THz signals. This work includes novel developments on optical frequency comb generation (integrated, 2THz span, 25 GHz spacing), frequency locking of semiconductor lasers (1kHz channel stability, 10 ns switching time) and high speed photodetectors integrated with antennas (3dB bandwidth > 108 GHz, 0.2 A/W responsivity , 148 muW output power at 457 GHz)

Wavelength conversion of 1.53 micron picosecond pulses in an ion-implanted multiple quantum well all-optical switch

Summary form only given. This is, to our knowledge, the first report of both all-optical wavelength conversion in an Fabry Perot saturable absorber (SA) incorporating an ion-bombarded MQW SA, and fast recovery through ion-bombardment in an InGaAsP/InGaAsP MQW. The measured contrast ratio and recovery time of our device, 10 dB and 4.1 ps respectively demonstrate its potential for 40 Gbps WDM system applications.

A Monolithic MQW InP/InGaAsP-Based Comb Generator

We report a monolithic optical frequency comb generator using quaternary/quaternary multiple quantum well InP/InGaAsP material as phase modulator and gain medium in a frequency modulated (FM) laser design. The modulation was generated by quantum confined Stark effect to achieve a comb-line spacing of 24.4 GHz. The laser was fabricated using a single epitaxial growth step and quantum well intermixing to realize low loss phase and modulation sections. The resulting comb generator produces lines with a spacing exactly given by the modulation frequency, differential phase noise between adjacent lines of -82 dBc/Hz at 1 kHz offset and a comb spectrum width of up to 2 THz

Electrical isolation of MQW InGaAsP/InP structures by MeV iron ion implantation for vertical PIN modulators and photodiodes

Implantation-induced electrical isolation is a well known method in III-V semiconductor technology for the creation of local high resistivity regions in electronic and optoelectronic devices. In this paper, we demonstrate for the first time the fabrication of low leakage current (nA) planar vertical PIN modulators and detectors directly from epitaxial material using multiple energy Fe/sup +/ implant isolation in intentionally doped p- and n-type InP, and intrinsic multiple quantum well (MQW) InGaAsP layers.

Wavelength conversion of 1.53-µm-wavelength picosecond pulses in an ion-implanted multiple-quantum-well all-optical switch

An ultrafast high-contrast all-optical switch produced from a metal-organic vapor phase epitaxy-grown wafer incorporating a 50-period InGaAsP/InGaAsP multiple-quantum-well (MQW) saturable absorber (SA) and a distributed Bragg reflector is described. Postgrowth implantation with 4-MeV nitrogen ions reduces the MQW free-carrier lifetime, and hence the switch recovery time, to 5.2 ps. Incorporation of the MQW SA in an optical cavity results in switching contrast ratios greater than 10 dB. The all-optical switch is used to perform wavelength conversion of 2-ps pulses.

10 Gb/s noise suppression using an ion implanted waveguide saturable absorber

Noise suppression of 3 dB per pass is demonstrated using a top-implanted passive InGaAsP/InGaAsP multiple quantum well ridge waveguide saturable absorber. The contrast ratio and recovery time are 3 dB and ~16 ps respectively.

Monolithically integrated QCSE-tuned InGaAsP MQW ridge waveguide DBR laser

The first QCSE-tuned ridge waveguide InGaAsP MQW DBR laser monolithically integrated with QW-intermixed tuning sections is demonstrated. QCSE is used for tuning with minimal thermal effects over ~7 nm for <2.5 V applied voltage change