Enhancement of the spectral width of high-power 1.5 mu m integrated superluminescent light source by quantum well intermixing process

A novel type of integrated InGaAsP superluminescent light source was fabricated based on the tilted ridge-waveguide structure with selective-area quantum well (QW) intermixing. The bandgap structure along the length of the device was modified by impurity free vacancy diffusion QW intermixing, The spectral width was broadened from the 16 nm of the normal devices to 37 nm of the QW intermixing enhanced devices at the same output power level. High superluminescent power (210 mW) was obtained under pulsed conditions with a spectral width of 37 nm.

Monolithically integrated semiconductor optical amplifier and electroabsorption modulator with dual-waveguide spot-size converter input and output

We have demonstrated an electroabsorption modulator and semiconductor optical amplifier monolithically integrated with novel dual-waveguide spot-size converters (SSC) at the input and output ports for low-loss coupling to a planar light-guide circuit silica waveguide or cleaved single-mode optical fibre. The device was fabricated by means of selective-area MOVPE growth, quantum well intermixing and asymmetric twin waveguide technologies with only a three-step low-pressure MOVPE growth. For the device structure, in the SOA/EAM section, a double ridge structure was employed to reduce the EAM capacitances and enable high bit-rate operation. In the SSC sections, buried ridge structure (BRS) was incorporated. Such a combination of ridge, ATG and BRS structure is reported for the first time in which it can take advantage of easy processing of the ridge structure and the excellent mode characteristic of BRS. At the wavelength range of 1550-1600 nm, lossless operation with extinction ratios of 25 dB dc and more than 10 GHz 3 dB bandwidth is successfully achieved, The beam divergence angles of the input and output ports of the device are as small as 8.0 degrees x 12.6 degrees, resulting in 3.0 dB coupling loss with a cleaved single-mode optical fibre.

10 Gbit s(-1) electroabsorption-modulated laser light-source module using selective area MOVPE

A distributed-feedback (DFB) laser and a high-speed electroabsorption (EA) modulator are integrated, on the basis of the selective area MOVPE growth (SAG) technique and the ridge waveguide structure, for a 10 Gbit s(-1) optical transmission system. The integrated DFB laser/EA modulator device is packaged in a compact module with a 20% optical coupling efficiency to the single-mode fibre. The typical threshold current is 15 mA, and the side-mode suppression ratio is over 40 dB with the single-mode operation at 1550 nm. The module exhibits 1.2 mW fibre output power at a laser gain current of 70 mA and a modulator bias voltage of 0 V. The 3 dB bandwidth is 12 GHz. A dynamic extinction ratio of over 10 dB has been successfully achieved under 10 Gbit s(-1) non-return to zero (NRZ) operation, and a clearly open eye diagram is obtained.

Monolithically integrated laser diode and electroabsorption modulator with dual-waveguide spot-size converter input and output

We have demonstrated a 1.60 mu m ridge-structure laser diode and electroabsorption modulator monolithically integrated with buried-ridge-structure dual-waveguide spot-size converters at the input and output ports for low-loss coupling to a cleaved single-mode optical fibre by means of selective area growth and asymmetric twin waveguide technologies. The devices emit in single transverse and quasi-single longitudinal modes with a side mode suppression ratio of 25.6 dB. These devices exhibit 3 dB modulation bandwidth of 15.0 GHz and modulator extinction ratios of 14.0 dB dc. The output beam divergence angles of the spot-size converter in the horizontal and vertical directions are as small as 7.3 degrees x 10.6 degrees, respectively, resulting in 3.0 dB coupling loss with a cleaved single-mode optical fibre.

A 10-GHz bandwidth electroabsorption modulated laser by ultra-low-pressure selective area growth

A novel integration technique has been developed using band-gap energy control of InGaAsP/InGaAsP multi-quantum-well (MQW) structures during simultaneous ultra-low-pressure (22 mbar) selective-area-growth (SAG) process in metal-organic chemical vapour deposition. A fundamental study of the controllability of band gap energy by the SAG method is performed. A large band-gap photoluminescence wavelength shift of 83nm is obtained with a small mask width variation (0-30 mu m). The method is then applied to fabricate an MQW distributed-feedback laser monolithically integrated with an electroabsorption modulator. The experimental results exhibit superior device characteristics with low threshold of 19 mA, over 24 dB extinction ratio when coupled into a single mode fibre. More than 10GHz modulation bandwidth is also achieved, which demonstrates that the ultra-low-pressure SAG technique is a promising approach for high-speed transmission photonic integrated circuits.

Monolithic integration of an InGaAsP-InP strained DFB laser and an electroabsorption modulator by ultra-low-pressure selective-area-growth MOCVD

The design and basic characteristics of a strained InGaAsP-InP multiple-quantum-well (MQW) DFB laser monolithically integrated with an electroabsorption modulator (EAM) by ultra-low-pressure (22 mbar) selective-area-growth (SAG) MOCVD are presented. A fundamental study of the controllability and the applicability of band-gap energy by using the SAG, method is performed. A large band-gap photoluminescence wavelength shift of 88 mn. was obtained with a small mask width variation (0-30 mu m). The technique is then applied to fabricate a high performance strained MQW EAM integrated with a DFB laser. The threshold current of 26 mA at CW operation of the device with DFB laser length of 300 mu m and EAM length of 150 mu m has been realized at a modulator bias of 0 V. The devices also exhibit 15 dB on/off ratio at an applied bias voltage of 5 V.

Electroabsorption-Modulated DFB laser Integrated.With dual-core spot-size converters

A 1.55-mu m single shallow ridge electroabsorptionmodulated distributed feedback laser that is monolithically integrated with a buried-ridge-stripe dual-core spot-size converter (SSC) at the input and output ports was fabricated by combining selective area growth, quantum-well intermixing, and dual-core integration techniques simultaneously. These devices exhibit a threshold current of 34 mA, a side mode suppression ratio of 38.0 dB, a 3-dB modulation bandwidth of 11.0 GHz, and a modulator extinction ratio of 25.0 dB dc. The output beam divergence angles of the SSC in the horizontal and vertical directions are as small as 7.3 degrees x 18 degrees, respectively, resulting in 3.2-dB coupling loss with a cleaved single-mode optical fiber.

MQW electroabsorption modulator-integrated DFB laser modules for high-speed transmission

Details of the design, fabrication and testing of a strained InGaAsP/InGaAsP multiple quantum well (MQW) electroabsorption modulator (EAM) monolithically integrated with a DFB laser by ultra-low-pressure selective area growth (SAG) are presented. The method greatly simplifies the integration process. A study of the controllability of band-gap energy by SAG has been performed. After being completely packaged in a seven-pin butterfly compact module, the device successfully performs 10 Gb s(-1) nonreturn to zero (NRZ) operation on uncompensated transmission span >53 km in a standard fibre with a 8.7 dB dynamic extinction ratio. A receiver sensitivity of -18.9 dBm at a bit error rate (BER) of 10(-10) is confirmed. 10 GHz short pulse trains with 15.3 ps pulsewidth have also been generated.

High-quality multiple quantum wells selectively grown with tapered masks by ultra-low-pressure MOCVD

An InGaAsP/InGaAsP multiple quantum wells (MQWs) selectively grown by ultra-low-pressure (22 mbar) metal-organic chemical vapor deposition was investigated in this article. A 46 nm photoluminescence peak wavelength shift was obtained with a small mask width variation (15-30 mu m). High-quality crystal layers with a photoluminescence (PL) ftill-width-at-half-maximum (FWHM) of less than 30 meV were achieved. Using novel tapered masks, the transition-effect of the tapered region was also studied. The energy detuning of the tapered region was observed to be saturated with the larger ratio of the mask width divided to the tapered region length. (C) 2005 Elsevier B.V. All rights reserved.

1.55-mu m Ridge DFB laser and electroabsorption modulator integrated with buried-ridge-stripe dual-waveguide spot-size converter output

A 1.55-mu m ridge distributed feedback laser and electroabsorption modulator monolithically integrated with a buried-ridge-stripe dual-waveguide spot-size converter (SSC) at the output port for low-loss coupling to a cleaved single-mode optical fiber was fabricated by means of selective area growth, quantum-well intermixing, and dual-core technologies. These devices exhibit threshold current of 28 mA, 3-dB modulation bandwidth of 12.0 GHz, modulator extinction ratios of 25.0-dB dc. The output beam divergence angles of the SSC in the horizontal and vertical directions are as small as 8.0 degrees x 12.6 degrees, respectively, resulting in 3.2-dB coupling loss with a cleaved single-mode optical fiber.

Resonant tunnelling diodes and high electron mobility transistors integrated on GaAs substrates

A1GaAs/1nGaAs high electron mobility transistors (HEMTs) and AlAs/GaAs resonant tunnelling diodes (RTDs) are integrated on GaAs substrates. Molecular beam epitaxy is used to grow the RTD on the HEMT structure. The current-voltage characteristics of the RTD and HEMT are obtained on a two-inch wafer. At room temperature, the peak-valley, current ratio and the peak voltage are about 4.8 and 0.44 V, respectivcly The HEMT is characterized by a, gate length of 1 mu m, a, maximum transconductance of 125 mS/mm, and a threshold voltage of -1.0 V. The current-voltage, characteristics of the series-connected RTDs are presented. Tire current-voltage curves of the parallel connection of one RTD and one HEMT are also presented.

Electroabsoorption-modulated laser light-source module using selective area growth for 10 Gb/s transmission

In this work, a novel light source of strained InGaAsP/InGaAsP MQW EAM monolithically integrated with DFB laser is fabricated by ultra-low-pressure (22 x 10(2) Pa) selective area growth ( SAG) MOCVD technique. Superior device performances have been obtained, sue h as low threshold current of 19 mA, output light power of about 7 mW, and over 16 dB extinction ratio at 5 V applied voltage when coupled into a single mode fiber. Over 10 GHz 3 dB bandwidth in EAM part is developed with a driving voltage of 3 V. After the chip is packaged into a 7-pin butterfly compact module, 10-Gb/s NRZ transmission experiments are successfully performed in standard fiber. A clearly-open eye diagram is achieved in the module output with over 8.3 dB dynamic extinction ratio. Power penalty less than 1.5 dB has been obtained after transmission through 53.3 km of standard fiber, which demonstrates that high-speed, low chirp EAM/DFB integrated light source can be obtained by ultra-low-pressure (22 x 102 Pa) SAG method.

Electroabsorption modulated semiconductor optical amplifier monolithically integrated with spot-size converters

We have demonstrated an electroabsorption modulator (EAM) and semiconductor optical amplifier (SOA) monolithically integrated with novel dual-waveguide spot-size converters (SSCs) at the input and output ports for low-loss coupling to planar light-guide circuit silica waveguide or cleaved single-mode optical fiber. The device is fabricated by means of selective-area MOVPE growth (SAG), quantum well intermixing (QWI) and asymmetric twin waveguide (ATG) technologies with only three steps low-pressure MOVPE growth. For the device structure, in SOA/EAM section, double ridge structure was employed to reduce the EAM capacitances and enable high bit-rate operation. In the SSC sections, buried ridge stripe (BRS) were incorporated. Such a combination of ridge, ATG and BRS structure is reported for the first time in which it can take advantage of both easy processing of ridge structure and the excellent mode characteristic of BRS. At the wavelength range of 1550-1600 nm, lossless operation with extinction ratios of 25 dB DC and more than 10 GHz 3-dB bandwidth is successfully achieved. The beam divergence angles of the input and output ports of the device are as small as 8.0 degrees x 12.6 degrees, resulting in 3.0 dB coupling loss with cleaved single-mode optical fiber. (c) 2005 Elsevier B.V. All rights reserved.

Improving response speed of electrooptical switch in silicon-on-insulator by modifying modulation area structure

This paper reports on the simulation of two 2 x 2 electrooptical switches with different modulation area structures in silicon-on-insulator (SOI). A two-dimensional (2D) semiconductor device simulation tool PISCES-II has been used to analyze the dc and transient behaviors of the two devices. The modeling results show that the switch with an N+-I-P+-I-N+ modulation structure has a much faster response speed than the device with a P+-I-N+ modulation structure, although the former requires slightly stronger injection power.

High performance of 1.55 mu m DFB integrated with vertically tapered self-aligned spot-size converter

A new type of self-aligned spotsize converter (SSC) integrated 1.55 mum DFB lasers had been proposed in this article. The upper optical confinement layer and the butt-coupled tapered thickness waveguide were regrown simultaneously, which not only offered the separate optimization of the active region and the integrated SSC, but also reduced the difficulty of the butt-joint selective regrowth. The vertical and horizontal far field angles were 9degrees and 12degrees respectively, the 1- dB misalignment tolerance were both 3.6 and 3.4 mum. The directed coupling efficiency to tapered single mode fiber was 48%.