Diode Laser

Symbol

Information

A diode laser is a semiconductor device that generates coherent light based on the interaction between electrical current and the active laser medium. It operates similarly to a conventional diode but incorporates additional effects such as thermal resistance and junction capacitance, which influence its behavior.

The current-voltage relationship of the diode laser is given by:

\[I = I_{ss} \cdot \left( e^{\frac{V}{n V_t}} - 1 \right) + R_{th} V + C_j \frac{dV}{dt}\]

Where:

\(I\) is the current through the diode laser (Amperes)
\(V\) is the voltage across the diode laser (Volts)
\(I_{ss}\) is the saturation current, representing the small leakage current in reverse bias
\(V_t\) is the thermal voltage, depending on temperature
\(n\) is the ideality factor, representing how closely the diode follows the ideal diode equation
\(R_{th}\) is the thermal resistance, modeling heat dissipation
\(C_j\) is the junction capacitance, representing charge storage effects

Diode lasers are widely used in optical communication, laser printing, barcode scanning, and material processing.

Ports

p: Anode (positive terminal)
n: Cathode (negative terminal)

Model

The Diode Laser model implements an advanced nonlinear diode with thermal and capacitance effects.

A diode laser generates light and follows a nonlinear current-voltage relationship while considering thermal and charge storage effects.

Attributes:

V (signal): Input voltage signal across the diode laser, defined between nodes (p, n).

I (signal): Output current signal through the diode laser, defined between nodes (p, n).

Iss (param): Saturation current (default: 1.0e-15 A).

Vt (param): Thermal voltage (default: 0.025 V).

n (param): Ideality factor (default: 1).

Rth (param): Thermal resistance (default: 10 Ω).

Cj (param): Junction capacitance (default: 1e-9 F).

Methods:

analog(): Defines the diode laser behavior using the Shockley equation with thermal and capacitance effects:

from pyams.lib import model, signal, param, voltage, current, explim, ddt

class DiodeLaser(model):
    """
    Diode Laser model incorporating thermal resistance and junction capacitance.
    """
    def __init__(self, p, n):
        # Signal declaration
        self.V = signal('in', voltage, p, n)
        self.I = signal('out', current, p, n)

        # Parameter declaration
        self.Iss = param(1.0e-15, 'A', 'Saturation current')
        self.Vt = param(0.025, 'V', 'Thermal voltage')
        self.n = param(1, ' ', 'The ideality factor')
        self.Rth = param(10, 'Ω', 'Thermal resistance between anode and cathode')
        self.Cj = param(1e-9, 'F', 'Junction capacitance between anode and cathode')

    def analog(self):
        """Defines the diode laser’s current-voltage relationship"""
        self.I += self.Iss * (explim(self.V / (self.n * self.Vt)) - 1) + self.Rth * self.V + self.Cj * ddt(self.V)

Command syntax

The syntax for defining a diode laser in a PyAMS simulation:

# Import the model
from pyams.models import DiodeLaser

# DLname: is the name of the diode laser instance
# p, n: The connection points in the circuit
DLname = DiodeLaser(p, n)