In this article, combined a multi-population rate equations (MPREs) of quantum dot lasers (QDLs) with an equivalent circuit simulation method of multi quantum well lasers, a multi-population quantum dot lasers equivalent circuit model (MPQDLs-ECM) is developed to simulate the lasing, temperature and the turn-on delay characteristics of the MPQDLs. Calculated results show that the QDs with different energy levels lase independently at low temperature but lase coherently at high temperature. Also, the GS and ES are observed to be in three different turn-on cases with the excitation from the low level to high level. All the calculations agree well with other reported experimental and theoretical results, indicating that the MPQDLs-ECM can be of great importance in simulating, analyzing, optimizing as well as predicting the characteristics of the QDs based devices.
In this paper, we propose and experimentally demonstrate an all-optical non-return-to-zero (NRZ) to return-to-zero (RZ)
format conversion using semiconductor ring laser (SRL). A 155Mb/s NRZ optical data signal is injected into the
counterclockwise (CCW) direction of the SRL and an optical logic clock signal is injected to the clockwise (CW)
propagation direction. The power and wavelength on both sides are adjusted so that during the 'high' level of the clock,
the SRL is held to the CW direction regardless of the logic value of the corresponding data bit. The SRL will only be
switched to the CCW direction when the input data is 'high' and when the clock level is 'low'. Therefore the NRZ
format signal is converted to RZ format signal, with a duty cycle decided by the duty cycle of the optical clock.
Extinction ratio of > 10 dB has been achieved and the scheme can also be used for all-optical 3R. Although the speed of
the signal is yet limited, higher speed can be achieved with faster SRL devices.
We report on a novel mirror design for micro-ring semiconductor ring lasers that uses those mirrors to connect
straight waveguide sections in a closed loop. The nearly parabolic mirrors are designed by ray-tracing to optimize
their shape. The efficiency of the designs is verified with FDTD simulations, with a simulated coupling efficiency
of 98%. We have successfully fabricated devices based on this design with an equivalent circular ring radius of
16μm. These devices operate in continuous wave at room temperature with a threshold current of only 22mA
and an emission wavelength of 1.55μm.
The semiconductor ring laser (SRL) is attracting more and more interest as a potential all-optical logic device. Whilst
previous operations used electrical modulation to induce switching, for all-optical applications such as all optical
switching, regeneration, and optical memory it is necessary to switch using an external optical signal. When operated as
a monostable way at 110 mA (just above the threshold of 80 mA) where the device operates in the bidirectional regime,
SRL should also be dynamically forced to work in clockwise (CW) and anticlockwise (CCW) directions depending on
the external injection direction. In this paper the response characteristics of SRL to external optical injection which fed
into SRL by CCW direction are investigated. Both output directions have highly nonlinear relationship with injection
signal power and their responses are highly digital. This operation is also simulated in both directions and the agreement
with experiment is very good apart from the injection power scale. This confirms that the SRL power is constant above a
certain injection power level in both on and off directions, which can be further verified by future devices with 2
Time-slot interchange is investigated using an optical buffer with a large variable delay based on an active-vertical-coupler crosspoint switch. The delay could range from 1 to 999 time slots in our scheme, and the length of the time slot is correspondingly flexible. The experiment could be performed at a data rate of 10 Gbit/s. The results show the power penalty is about 1.5 and 5.6 dB, respectively, when the packets pass through two buffers and through one buffer nine times
We experimentally demonstrate a novel decimal optical buffer scheme based on multi-loop configuration and single
switch element--an optical crosspoint switch (OXS) matrix. Our results show that by using a differential phase-shift
keying (DPSK) payload in the buffer can outperform OOK payload with 3.2 dB sensitivity improvement owing to its
alleviation of patterning induced degradation compared to OOK payload, clearly validating DPSK as a promising
modulation format to overcome nonlinear impairments and to extend number of hops in all-optical packet switching
We experimentally demonstrate optical packet switching with less than 8 ns switching speed for a 10 Gb/s RZ payload and a 155 Mb/s NRZ label using a 4×4 optical crosspoint switch (OXS) matrix. The wavelength dependence of the OXS is also investigated in terms of the receiver sensitivity and the output OSNR. Very good switching performance can be achieved from 1535 nm to 1561 nm. Our results suggest that the OXS can be a promising device for switching future
high speed impulse coded signals.
Optical gate switch is a vital part of all-optical signal processing and being investigated. A kind of optical gate switch, called ultrafast nonlinear interferometer (UNI) consisting of a SOA, which is used as a nonlinear component in the path of one-arm MZI, has the advantages of a simple structure and high speed. In this letter, we report a 10GHz all-optical switch based on an UNI. Through our experiment, we found that the switching window depends on many parameters, including the injection current of SOA, the power of control pulse, and the power of continual light.