OptiSystem Applications

Receiver Noise—PIN

There are two fundamental noise mechanisms in a photodetector: shot noise thermal noise Receiver Shot and Thermal noise.osd details the signal degraded by thermal and shot noise in the PIN photodetector. The low-pass filter has a cutoff frequency with the same value as the bit rate. Figure 1: Receiver Shot and Thermal noise The upper…

Receiver Noise—Shot Noise Enhancement with APD

Optical receivers with APD generally provide a higher SNR for the same incident optical power. The improvement in the SNR is due to the internal gain that increases the photocurrent by the multiplication factor M. Figure 1: Receiver PIN x APD The APD photodetector systems (see Figure 2) has a Q factor higher that the…

Receiver Sensitivity—Bit Error Rate (BER)

The performance criteria for digital receivers if governed by the bit-error-rate (BER), defined as the probability of incorrect identification of a bit by the decision circuit of the receiver. Receiver BER – Q factor.osd shows the BER and Q factor at the data recovery stage for different values of input power. Receiver BER – Q…

Receiver sensitivity—Minimum input power

This example shows the minimum optical power that a receiver needs to operate reliably with a BER below a specific value (see Figure 1). In this example, you calculate this input power by targeting a BER of 10-9, a Q factor equal to 6 for a PIN photodetector, and an APD. Figure 1: Receiver Min.…

Sensitivity degradation—Extinction ratio

A simple source of power penalty is related to the energy carried by 0 bits. Some power is emitted by transmitters even in the off-state. Sensitivity Degradation – ER.osd includes an external modulated laser where you can specify the extinction ratio at the modulator (see Figure 1). Figure 1: Sensitivity Degradation – ER In this…

Signal degradation – Jitter

Jitter is defined as the short-term variations of a digital signal’s significant instants from their ideal positions in time. Significant instants could be (for example) the optimum sampling instants. Project Signal Degradation – Jitter.osd (Figure 1) demonstrates the setup for the ‘Electrical Jitter’ component. It requires an electrical signals and the clock signal from the…

Electrical PLL

The system demonstrates an electrical phase-locked loop. Sample: EPLL.osd The layout presented in the figure below is PLL system configured with a phase detector, a low pass filter and a voltage controlled oscillator. This example shows the response of a PLL to a sequence of pulses modulated in frequency to an electrical carrier at 1GHz.…

100 nm bandwidth flat-gain Raman amplifier – Average power model

Optical System - Figure 8 Counter-propagating pump

This lesson shows the performance of the Average power model in analysis of the 100 nm bandwidth Raman amplifier with multiwavelength backward pump. The parameters considered are close to these used in the experiment of [1]. The same experimental situation has been modeled by means of Average power model in [2]. As is well known…

Flattening the gain of broadband Raman amplifier with multipump configuration

Optical System - Figure 4 Optimized pump power spectrum

In this lesson, we will use the gain flattening type of optimization to optimize the pump powers for flattening the gain of a Raman amplifier. Fiber Raman amplifiers are recently getting much more attention in WDM systems due to their greatly extended bandwidth and distributed amplification with the installed fiber as gain medium [1]. It…

Optimizing the pump power and frequencies of Raman amplifiers for gain flatness

Optical System - Figure 5 Output power spectrum after the optimization

In this example, we show that the Gain Flattening type of optimization can be used to design multi-wavelength pumped Raman amplifiers with a flattened gain. Given amplifier specifications such as signal level, required gain profile, and number of allowed pump channels, the optimization procedure can generate a combination of pump wavelengths and input powers that…