A silicon (Si)-based, large-scale optical I/O chip will be a key device for a large-bandwidth, low-cost optical
interconnection employed in future high-performance computing systems. For these Si optical I/O chips, a significant
improvement in energy cost is strongly expected, hence, the use of micro ring-resonator (RR) based modulator is
assumed to be a promising approach. In order to handle a narrow and temperature-dependent operation bandwidth of the
RR-based modulator, we have proposed a novel Si transmitter that uses a cascaded RR MZ modulator and RR-based Si
hybrid laser. The RR-based Si hybrid laser is an external cavity laser integrating an InP SOA and a Si mirror chip
comprising a RR and DBR mirror. The SOA is flip-chip bonded to the Si mirror chip utilizing a precise flip-chip
bonding technology. The fabricated Si hybrid laser exhibited a low threshold current of 9.4mA, a high output power of
<15 mW, and a large wall-plug efficiency of 7.6% at 20°C. In addition, the device maintained a stable single longitudinal
mode lasing and a low RIN level of <-130 dB/Hz for 20-60°C. We also fabricated an integrated Si transmitter combining
a cascaded RR MZ modulator and RR-based Si hybrid laser. The 20-RR cascaded MZ modulator exhibited a 1-nm
operation bandwidth using multiple low-Q RRs. The modulator was driven with 10Gbps PRBS signal. For a temperature
range between 25 and 60°C, the lasing wavelength exhibited a red-shift of 2.5 nm, nevertheless, we confirmed clear eye
openings without adjusting the operating wavelength of the modulator.
We investigated the effect of the alloy composition of InGaAsP barrier layers on the photoluminescence (PL) properties
of InAs columnar quantum dots (CQDs) grown by metal organic vapor phase epitaxy (MOVPE). The PL wavelength of
the CQDs was controlled by the strain of the InGaAsP barrier layers for fixed bandgap wavelength conditions. The PL
intensity of the CQDs showed significant increase with the bandgap energy of the barrier layers, that is, with increasing
indium and phosphorus composition, due to the reduced defects and dislocation in the samples. The result is considered
to be related to the miscibility of the InGaAsP quaternary alloy at a low growth temperature. By applying a larger
bandgap energy to the barrier layers, triple-stacked CQDs with high crystalline quality was demonstrated in the 1.55-μm
region.
We have investigated the temperature dependence of InAs columnar quantum dots (CQDs) surrounded by InGaAsP
barriers with different bandgap energies toward high-temperature performance for semiconductor optical amplifiers. It
was found that larger bandgap energy in InGaAsP side barriers enabled to increase the quasi-Fermi level (F) separation
between the conduction and valence bands from theory. We have fabricated two types of CQD-SOAs with different side
barrier energies and compared temperature characteristics. Decrease in the material gains for CQD with a larger side
barrier bandgap was suppressed by 20% with increasing temperature from 25 °C to 85 °C.
High temperature (>125°C) resistant long-wavelength semiconductor lasers are attractive as light sources in a variety of
harsh environments. Here, we report extremely high temperature continuous-wave (CW) operation of QD lasers on
GaAs substrate emitted at 1300-nm-range by enhancing gain and increasing the quantized-energy separation of the QD
active layers. A suppression of the In out-diffusion during MBE from self-assembled InAs QDs significantly reduced
inhomogeneous broadening with high QD sheet density maintained. QD-FP laser exhibited record high CW-lasing
temperature for long-wavelength laser of 220°C and QD-DFB laser also exhibited high CW-lasing temperature of 150°C
by employing high gain QD active media.
We present a general method that improves the emission efficiency of InAs quantum dots (QDs) fabricated by antimony
surfactant-mediated growth. Unlike conventional InAs/GaAs QDs, we show that the control of the interface properties of
the InAs/Sb:GaAs QDs is crucial. Our method consists in growing InAs QDs on an antimony-irradiated GaAs surface, in
order to exploit the surfactant properties of antimony, and then removing the excess segregated antimony by applying a
high arsenic pressure before capping. In such a way, one benefits from the advantages of the antimony-surfactant
mediated growth (high density QDs, no coalescence, no emission blueshift after annealing), without the detrimental
formation of antimony-induced non-radiative defects. We show that the lasing characteristics of InAs/Sb:GaAs QD
lasers grown by metal organic chemical vapor deposition in the 1.3 μm band are drastically improved, with a reduced
threshold current density and higher internal quantum efficiency. These studies advance the understanding of key
processes in antimony-mediated growth of InAs QDs and will allow full utilization of its advantages for integration in
opto-electronic devices.
Recently, Optical WDM technology is introduced into backbone networks. On the other hand, as the future optical switching scheme, Optical Burst Switching (OBS) systems become a realistic solution. OBS systems do not consider buffering in intermediate nodes. Thus, it is an important issue to avoid overlapping wavelength reservation between partially interfered paths. To solve this problem, so far, the wavelength assignment scheme which has priority management tables has been proposed. This method achieves the reduction of burst blocking probability. However, this priority management table requires huge memory space. In this paper, we propose a wavelength assignment algorithm that reduces both the number of priority management tables and burst blocking probability. To reduce priority management tables, we allocate and manage them for each link. To
reduce burst blocking probability, our method announces information about the change of their priorities to intermediate nodes. We evaluate its performance in terms of the burst blocking probability and the reduction rate of priority management tables.
We demonstrated a novel two-dimensional photonic crystal (PC) based Symmetric-Mach-Zehnder-type all-optical switch (PC-SMZ) with InAs quantum dots (QDs) acting as a nonlinear phase-shift source. The 600-μm-long PC-SMZ with integrated wavelength-selective PC-based directional couplers and other PC components exhibited a 15-ps-wide
switching-window with a 2-ps rise/fall time at a wavelength of 1.3μm. Nonlinear optical phase shift in the 500-μm-long straight PC waveguide was also achieved at sufficiently low optical-energy (e.g., π phase shift at ~100-fJ control-pulse energy) due to the small saturation energy density of the QDs, which was enhanced in the PC waveguide, without having to use conventional measures such as SOAs with current-injected gain. These results pave the way to achieving novel PC- and QD-based photonic integrated circuits including multiple PC-SMZs and other novel functional devices.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.