M. Chien

A 16*1 wavelength division multiplexer with integrated distributed Bragg reflector lasers and electroabsorption modulators

The integrated operation of a 16*1 wavelength-division-multiplexed (WDM) source with distributed Bragg reflector (DBR) lasers and electroabsorption modulators has been demonstrated. By using repeated holographic exposures and wet chemical etching, 16 different wavelengths from 1.544 to 1.553 mu m with an average channel spacing of 6 AA are obtained. A high-performance combiner is used to obtain a very uniform coupling into the single-output waveguide, and with the integration of an optical amplifier an average optical power of -8 dBm per channel is coupled into a single-mode fiber.<<ETX>>

1.5 mu m multiquantum-well semiconductor optical amplifier with tensile and compressively strained wells for polarization-independent gain

A multiquantum-well optical amplifier for 1.5- mu m wavelength operation using alternating tensile and compressively strained wells in the active region is described. For each bias level measured, the polarization sensitivity of the amplifier gain is 1 dB or less averaged over the gain bandwidth. This amplifier is suitable for integration with other optical devices in photonic integrated circuits which require polarization-independent gain.<<ETX>>

Digitally tunable laser based on the integration of a waveguide grating multiplexer and an optical amplifier

A novel monolithic semiconductor laser is demonstrated. The optical cavity comprises a 1/spl times/N waveguide grating multiplexer connected to N optical amplifiers. By driving a specific output port, laser oscillation is obtained at the wavelength determined by the wavelength path through the multiplexer. Such a laser is very useful for WDM systems because it is capable of producing a comb of precisely spaced frequencies.<<ETX>>

InP-based multiple quantum well lasers with an integrated tapered beam expander waveguide

We demonstrate the integration of a laterally tapered adiabatic mode expander waveguide inside the cavity of diode lasers operating at 1.3 and 1.55 /spl mu/m wavelengths. This integration results in narrow output beam divergence with FWHM of 70 and 50 vertically and laterally respectively. The loss caused by the passive waveguide is minor and for devices operating at 1.55 (1.3) /spl mu/m threshold currents as low as 12 (22) mA and quantum efficiencies as high as 52% (51%) are obtained. Coupling to a cleaved optical fiber yields broad alignment tolerance with 1 dB excess loss for misalignment of /spl plusmn/2.6 /spl mu/m vertically and /spl plusmn/3.1 /spl mu/m laterally, with a minimum coupling loss of -3.5 dB.<<ETX>>

5.5-mm long InGaAsP monolithic extended-cavity laser with an integrated Bragg-reflector for active mode-locking

A 5.5-mm-long monolithic extended-cavity laser with an integrated Bragg-reflector in the InGaAsP system for active mode-locking at low repetition rates at a wavelength of 1.55 mu m has been fabricated. The device, which is designed to be used as a pulse source in long-distance soliton systems and optical time-division multiplexed systems, generates 20-ps-wide transform-limited pulses with a time-bandwidth product of 0.34 at a repetition rate of 8.1 GHz.<<ETX>>

Dynamic operation of a three-port, integrated Mach-Zehnder wavelength converter

Wavelength conversion using semiconductor optical amplifiers monolithically integrated in a three-part Mach-Zehnder configuration is achieved for data rates of 1 and 2.5 Gb/s. The three-port configuration allows efficient use of pump signal power, as well as counter-propagation of pump and converted signals, eliminating the need for a filter. Operation of the device at 5 Gb/s in a two-port configuration is also achieved. Dynamic extinction ratios larger than 13 dB, as well as both data-inverting and noninverting operation are demonstrated.<<ETX>>

A 1.54- mu m monolithic semiconductor ring laser: CW and mode-locked operation

The authors have fabricated a monolithic semiconductor ring laser with a diameter of 3.0 mm. A straight tangent waveguide provides two output ports through evanescent coupling. The laser, which exhibits a threshold current of 157 mA, operates in a single longitudinal mode with a linewidth of 900 kHz at a wavelength of 1.54 mu m. The device has been actively mode-locked at the fundamental resonance frequency of 9.0 GHz, yielding 27-ps pulses with a time-bandwidth product of 0.47. Differences in the characteristics of the pulses emitted from the two output ports indicate counterpropagating pulse trains, which because of the mode-locking scheme must collide in the modulated gain section.<<ETX>>

2.5 Gb/s transmission over 674 km at multiple wavelengths using a tunable DBR laser with an integrated electroabsorption modulator

We present a distributed Bragg reflector (DBR) laser/modulator photonic integrated circuit capable of transmission over 674 km of conventional fiber at 2.5 Gb/s. Transmission was performed at four wavelengths over a range of >4 nm. The bit error rate (BER) sensitivity achieved at each wavelength varied by less than 1.1 dB. These results produce a record bit rate-distance product at each wavelength of 1.7 Tb.km/s for monolithic transmitters through nondispersion shifted fiber. Such devices are ideal sources for multichannel wavelength-division-multiplexed (WDM) transmission systems.<<ETX>>

Short-cavity distributed Bragg reflector laser with an integrated tapered output waveguide

A distributed Bragg reflector strained-layer multiple-quantum-well laser at 1.5- mu m wavelength with an integrated tapered waveguide beam expander is discussed. The far-field FWHMs in the lateral and vertical directions are 10 and 15 degrees , respectively. A quantum efficiency of 17% out the tapered facet was measured with a corresponding threshold current of 28 mA. The alignment tolerances for coupling into a cleaved single-mode fiber are 9.5 and 7.5 mu m FWHM in the lateral and vertical directions, respectively. A 3-dB improvement for single-mode fiber coupling using a SELFOC lens was obtained.<<ETX>>

Tensile-strained InGaAs/InGaAsP quantum-well optical amplifiers with a wide spectral gain region at 1.55 mu m

A tensile-strained InGaAsP/InP multi-quantum-well optical amplifier is constructed which has >or=92 nm bandwidth at 16-dB gain for 50-mA drive current. The wide gain bandwidth is a result of both n=1 and n=2 contributions from the e to 1h transition. These results suggest wide tunability for lasers made from this material.<<ETX>>