Chih-Hsiao Chen

Four wave mixing in semiconductor optical amplifier

We have performed four wave mixing (FWM) measurements on a 2-section semiconductor optical amplifier(SOA) using CW and pulsed pump and probe beams. The FWM efficiency depends on the input pump power, the gain of the 2-section SOA and the wavelength separation between the pump and probe beams. A -19.1 dBm FWM signal power from the amplifier is achieved when the wavelength difference between the pump and probe beams is 2.5 nm. The pulse amplitude and pulse width of the FWM signal under the condition when the FWM signal is generated using pulsed pump and probe beams has been measured and analyzed. The results of the analysis are in agreement with the experimental data.

Demonstration of optical switch operation of an ultrafast nonlinear interferometer (UNI) with counter-propagating control pulse

We present all-optical switch operation of an ultrafast nonlinear interferometer (UNI) with counter-propagating control pulse. The measured extinction ratio for a 2.5 GHz signal is 10 dB. The geometry of the switch can be used as an optical demultiplexer in an OTDM system and high speed optical logic gate.

Static and dynamic analysis of tunable two-section high-speed distributed feedback laser utilizing the gain lever effect

Analysis of a novel semiconductor laser structure designed for obtaining wide tuning range along with high speed modulation response is presented. The laser consists of a composite cavity structure with two active (gain) sections. One of the sections has a grating corrugation while the other is flat. A detailed round-trip analysis is combined with the rate equations, which include sublinear gain/carrier relation, to perform steady-state and small-signal analysis. It is shown that the biasing (dc) condition of the different sections plays a critical role in the determination of the dynamic response of the device. In addition, we show that the gain-lever effect can be utilized for a considerable enhancement of the frequency modulation (FM) response. Other critical structural parameters such as the grating coupling coefficient and device geometry are discussed.

All optical frame clock extraction with polarization flag in OTDM system

Employing a polarization flag in a frame, we construct a point-to-point optical time division multiplexing (OTDM) communication system with a simple and feasible structure. In this system the frame clock is successfully extracted with an all optical method.

Cross gain saturation in semiconductor optical amplifier

We have carried out gain saturation experiments using pulsed pump and probe beams derived from gain switched DFB semiconductor optical amplifier lasers. The widths of both pump and probe pulses were 35 ps. The gain saturation of the probe takes place only when there is temporal overlap of the pump and probe beams in the amplifier.

Mode locked distributed Bragg reflector laser

Summary form only given. Mode locked semiconductor lasers are important for a wide range of fiber transmission systems. These include soliton generation and clock recovery in very high speed transmission systems. Compact, single chip, mode locked lasers are desirable for practical systems since they are likely to be more stable than the offchip external cavity designs. The fabrication and performance characteristics of a single chip mode locked laser is reported here. The laser emits near 1.55 /spl mu/m and is fabricated using the InGaAsP/InP material system.

Four-wave mixing in a semiconductor optical amplifier

We have performed four wave mixing (FWM) measurements on a 2-section semiconductor optical amplifier (SOA) using CW and pulsed pump and probe beams. The FWM efficiency depends on the input pump power, the gain of the 2-section SOA and the wavelength separation between the pump and probe beams. A -19.1 dBm FWM signal power from the amplifier is achieved when the wavelength difference between the pump and probe beams is 2.5 nm. The pulse amplitude and pulse width of the FWM signal under the condition when the FWM signal is generated using pulsed pump and probe beams has been measured and analyzed. The results of the analysis are in agreement with the experimental data.

Cross Gain Modulation in Semiconductor Optical Amplifier

We have performed cross gain modulation measurements on a 2-section semiconductor optical amplifier (SOA) using pulsed pump and probe beams. The probe amplitude and pulse width under this condition has been measured and analyzed. The results of the analysis are in agreement with the experimental data. These results are important for all optical networks utilizing gain saturation in amplifiers for signal add/drop function.

A 24-channel wavelength-selectable Er-fiber ring laser with intra-cavity waveguide-grating-router and semiconductor Fabry-Perot filter

We present an Er-doped fiber ring laser that operates with a single wavelength, which is selectable from any channel wavelength of a 24-channel silica waveguide grating WDM multiplexer. Error-free performance is demonstrated, we believe for the first time, for a waveguide-grating-router fiber laser at 5 Gb/s.

Semiconductor Optical Amplifier Array with Integrated Beam Expanders Coupled to Flat Fibers

A semiconductor optical 9mplifier array with 4 channels is presented. This SOA array was coupled to uncoated, flat end, single mode fibers using integrated adiabatic beam expanders, optical index matching gel, and specifically tailored TiO2 anti-reflection coatings. The TiO2 AR coating overcomes the indices misinatching of fiber glass and InP based device, and reduce optical reflection to 0.002% at 1.55 μm. The average coupling loss is 4.3 dB per facet for the devices measured. Fiber coupled small signal gain for the amplifiers is typically 11.6 dB and a saturation output power of 3.0 dBm. The method of characterization and optimization of the TiO2 coating is discussed.