U. Koren

Widely Tunable InGaAsP/InP Laser Based on a Vertical Coupler Intracavity Filter

Widely tunable semiconductor lasers are critical components for future wavelength division multiplexed networks and switching systems. Indeed, the total capacity of such systems is presently limited by the laser tuning range. The electrical tuning range of DFB and DBR lasers is limited to less than ~15nm. This limitation results from the fact that the fractional tuning range, Δλ/λ, of the fine-pitch Bragg grating wavelength-selective reflector is simply proportional to the normalized effective index change, ΔN/N. However, we have recently demonstrated that the grating-assisted vertical coupler provides an attractive bandpass filter that can be electrically tuned over a range substantially greater than a grating reflector for the same induced refractive index change [1,2]. Indeed, very recently a tunable twin guide laser that includes a vertical coupler structure between two nearly-synchronous guides exhibited evidence of extended, but irregular tuning [3]. Here we report a novel monolithic extended cavity laser with an integrated grating-assisted vertical coupler as a tunable intracavity filter. This laser has measured tuning range of 57nm and a tuning response that depends monotonically on the filter tuning current.

20 Gbit/s all-optical regeneration and wavelength conversion using SOA based interferometers

A novel optical translator that can perform 3R-regeneration and wavelength conversion of high-speed return-to-zero signals is demonstrated at 20 Gbit/s. Efficient retiming and bit-error-rate performance is measured using a Mach-Zehnder interferometer with integrated semiconductor optical amplifiers.

Four-Channel WDM Transmission Experiment Using a Photonic-Integrated-Circuit Transmitter

Wavelength-division-multiplexed (WDM) is one technique that is being pursued in order to more fully utilize the tremendous bandwidth of single-mode fiber. Experimental WDM systems have achieved aggregate bit rates of up to 32 Gbit/s [1,2]. Unfortunately, these systems have required high complexity at the transmitter, since individual lasers are employed. Recently, a photonic integrated circuit (PIC) was reported which contained three tunable multiple-quantum-well (MQW) lasers integrated with a passive waveguide combiner and an output optical amplifier [3]. We now describe a WDM transmission system which uses a similar device containing four lasers, each modulated at 2 Gbit/s. We report on transmission through 36 km of conventional fiber at an operating wavelength of 1.5 μm.

Wide-band amplitude modulation by electrooptic tuning of the center wavelength in short-cavity distributed Bragg reflector lasers

This paper describes wide-band electrooptic modulation of a short-cavity distributed Bragg reflector laser. Efficient amplitude modulation, in both small and large signal regimes, is obtained by modulation of the center Bragg reflector wavelength via electrooptic tuning. The role of the refractive index dynamics in determining the characteristics of a diode laser employing wavelength dependent feedback is also addressed. >

High power laser-amplifier photonic integrated circuit for 1.48 micron wavelength operation

Laser-amplifier photonic integrated circuits (PIC’s) with high coupling efficiency between the laser and amplifier elements, using the InP material system, have been described previously [l-3]. Surface emitting laser amplifier devices have also been reported in the GaAs system using second order Bragg reflector gratings [4]. In the present work we describe a strained layer MQW laser-amplifier PIC intended for use as a high power source for pumping erbium doped fiber amplifiers (EDFA’s) at 1.48 micron wavelength. Multiple quantum well (MQW) optical amplifiers have extremely high saturation output powers [5,6], making them very suitable for high power applications.

Electrooptical logic operations with two-electrode distributed feedback injection lasers

Recently, we demonstrated utilization of the two-mode degeneracy property1 of distributed feedback (DFB) injection lasers for high-speed electrooptical switching.2 This paper reports electrooptical logic operations using a two-electrode DFB laser at a 1.3-μm wavelength. A complete set of AND, NAND, OR, NOR, and INVERT logic gates was demonstrated by detecting the output light of one of the two degenerate modes that were switched by electrical signals applied to the two electrodes.

Integrated electroabsorption modulator/semiconductor optical amplifier for 2.5 Gbit/s modulation with fiber-to-fiber gain

We have examined the performance of an integrated semiconductor optical amplifier/elctroabsorption (SOA-EA) modulator device and find that the device provides good performance at 2.5 Gbit/s modulation, with fiber-to-fiber gain, and low polarization sensitivity. With improvements in packaging, the high-speed performance of this device should be extended to higher modulation rates.

Mach-Zehnder wavelength converter with integrated preamplifiers

Summary form only given. In summary, a Mach-Zehnder WDM fibre network wavelength converter with variable input and output wavelengths has been presented. The integrated signal and probe pre-amplifiers potentially reduce input power requirements. Around 25-dB extinction ratio has been demonstrated, as well as operation at 2.5 Gbit/s.