KEYWORDS: Analog electronics, Modulation, Beam controllers, Signal generators, Solids, Telecommunications, Polarization, Process control, Signal processing, Modulators
A novel simple optical pulse width modulation generator (OPWMG) based on injection-locking property of a single mode FP-LD (SMFP-LD) has been proposed and experimentally verified. The OPWMG consists of a SMFP-LD (which acts as comparator), an optical sinusoidal wave source (analog input), and a continuous optical beam (control signal). The power required for fully injection-locking the SMFP-LD acts as the referent power whereas the combination power of continuous optical beam and analog optical sinusoidal signals work as control signals for changing the duty cycle of the proposed OPWMG. The presence of only continuous optical beam is not sufficient to suppress the dominant mode of SMFP-LD with high ON/OFF contrast ratio; however, the application of additional sinusoidal wave of constant amplitude and frequency, the dominant mode of SMFP-LD can be suppressed for the certain time window. Since, injection-locking power is dependent with the combined power of input injected continuous beam and sinusoidal optical wave, the time window of injection-locking can be varied by changing input beam power which provides different duty cycle of 13% to 68% at the output. Current available schemes for generating PWM signals are in electrical domain, hence, they need to convert electrical signals into optical domain by using expensive O/E converters for application in optical control and signal processing. The proposed OPWMG scheme has several advantages, such as low cost, low power consumption (~0.5 mW) which can be used for various applications where the effect of EMI/EMR is considered as an important factor such as control circuit for high voltage converters in power plant and electrical vehicles.
An all-optical ON-OFF switch is demonstrated using a single-mode Fabry-Perot laser diode. The operation principle of
the proposed switch is the gain modulation of injection locked single mode Fabry-Perot laser diode (SM FP-LD) by an
external control beam. In this paper, the operation principle is explained and a 10 Gb/s data signal is switched ON and
OFF with a control signal of 200 MHz. We measured the switched output with an extinction ratio of 15.4 dB. The rising
and falling times of the switch were measured as 90 ps and 80 ps, respectively.
In this paper, an all-optical 1x2 switch is demonstrated based on gain modulation of injection locked Fabry-Perot laser
diode (FP-LD). The control circuit generates set and reset states, which are used to perform 1x2 switch function. The
switch output state is maintained once it starts to operate, whether the control signal is present or absent. In the
experiment, with extinction ratio of 13.2 dB the switch output eye diagram is recorded.
An optical S-R latch is demonstrated using two injection locked single-mode (SM) Fabry-Perot laser diode (FP-LD). The
S-R latch is based on the bi-stability and injection-locking properties of FP-LD. The latch performs simultaneous
inverted and non-inverted outputs in set and reset states. The proposed latch performs very well both in set and reset
conditions. The switching times of the latch both for inverted and non-inverted outputs in set and reset conditions were
measured by oscilloscope and recorded as about 90 ps. For the latching function, very low powers of set and reset signal
were required. Power of set signal was -17 dBm and that of reset signal was -7 dBm.
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