OptiSPICE from Optiwave was developed for designing and simulating optoelectronic circuits at the transistor level, covering, among other things, laser drivers, transimpedance amplifiers, optical interconnects and electronic equalizers.
Why doesn't classical SPICE solve the whole problem?
SPICE is the standard tool for simulating electronic circuits. A problem arises when the same circuit contains elements whose optical state depends on the electrical state, and vice versa. An example would be: driver → laser → optical path → photodiode → TIA. The electrical signal drives the light source, the light propagates along the optical path, and then the detector converts it back into an electrical signal. OptiSPICE solves such a circuit as a coupled optoelectronic problem — the manufacturer emphasizes the ability to obtain self-consistent solutions even in circuits with feedback that spans the optical and electrical parts.
What does "transistor level" mean?
System-level simulation usually operates on functional blocks. For example: laser → modulator → fiber → receiver. In OptiSPICE you can go a level deeper and analyse the driving and receiving electronics as an actual circuit. This lets you study the impact of:
- transistors;
- RLC elements;
- voltage and current sources;
- amplifiers;
- driving parameters;
- electrical-to-optical interfaces.
Optiwave also publishes tutorials covering classical electronic circuits, such as transistor amplifiers, CMOS circuits, and op-amp macro models.
Example: a laser driver
A laser doesn't work on its own — it has to be properly biased and modulated. The model can include: data source → driver → laser. The designer can analyse the bias current, the modulation current, the signal rise time, the transistors' operation, the laser's response, and the relationship between the electrical and optical waveforms. In a typical system-level model, the driver might be treated as an ideal block — in OptiSPICE you can instead check whether the electronics itself is becoming a limiting factor.
Example: a TIA-based receiver
On the receive side, a typical path might look like: photodiode → TIA → further amplification stages → decision circuit. The transimpedance amplifier converts the current generated by the photodiode into a voltage, and its parameters affect bandwidth, signal amplitude, pulse shape, stability, noise, and the receiver's ability to operate at high bit rates. OptiSPICE lists transimpedance amplifiers directly among the program's typical applications.
Feedback between optics and electronics
This is one of the most important differences between simply linking two separate simulators and a genuine optoelectronic environment. Imagine a circuit in which a photodetector measures optical power, and the electronics uses that signal to regulate the laser's driving current. This creates a loop: laser → light → detector → electronics → laser. The optics affects the electronics, and the electronics, in turn, affects the optics. OptiSPICE was designed precisely for circuits containing this kind of feedback.
Parameter extraction — building a model from measured data
Simulation is only useful when the component models match reality. OptiSPICE includes parameter-extraction tools. Among others, Optiwave describes:
- Laser Parameter Extractor — for fitting a laser model's parameters based on static and dynamic characteristics;
- Filter Parameter Extractor — for converting S-parameters into a pole-residue representation;
- Multimode Fiber Parameter Extractor — including a mode solver that lets you build fiber libraries from a defined refractive-index profile.
This is an important link between measurement and simulation. Instead of relying purely on an idealized element, you can build a model based on data from a real device.
Time-domain waveform analysis
In optoelectronic circuits, it's not just the average value that matters — you need to look at the waveforms V(t), I(t), P(t). This lets you analyse delays, overshoot, oscillations, response speed, distortion, and the circuit's behaviour during switching. OptiSPICE integrates circuit simulation with time-domain waveform analysis.
OptiSPICE vs. OptiSystem
OptiSPICE and OptiSystem are not competing tools — they operate at different levels of detail. OptiSPICE is the right choice when what matters is transistors, driving circuits, TIAs, the coupling of electronics and photonics, and feedback. OptiSystem is the right choice when what's being analysed is a complete transmission system: BER, eye diagram, OSNR, propagation through the whole link, and the behaviour of many system blocks together. Optiwave supports carrying data from OptiSPICE into OptiSystem's post-processing environment, where you can perform, among other things, eye-diagram, optical-spectrum, BER and Q-factor analysis.
From a transistor to BER
This opens up a very interesting design possibility. You can move through successive levels: transistor parameter → electrical waveform → light modulation → optical waveform → reception → eye diagram and BER. This lets you assess whether a degradation in transmission quality is really coming from the optical channel, or, for instance, from insufficient bandwidth in the driver or the TIA.
Compact models and component data
Fully simulating every element with electromagnetic methods isn't needed at the circuit level. Optoelectronics therefore relies on compact models that describe a component's behaviour at a much lower computational cost. Such a model, however, should have a defined range of validity. If it was derived from measurements over only a narrow range of currents or frequencies, it shouldn't be used, without checking, under completely different conditions. This, again, illustrates the importance of model validation.
What OptiSPICE is not for
OptiSPICE is not a replacement for an electromagnetic solver. If you're designing the geometry of a waveguide, a resonator, a coupler, or a nanostructure, you need tools such as OptiMode, OptiBPM, OptiFDTD or OptiOmega. Once a component's behaviour has been determined, its model can then be used at the circuit level. This follows the hierarchy: component physics → compact model → optoelectronic circuit → system.
Applications
OptiSPICE is especially useful when designing:
- optical transmitters;
- receivers;
- laser drivers;
- TIAs;
- optical interconnects;
- electro-optic circuits;
- photonic interconnects;
- sensors with readout electronics;
- circuits with optoelectronic feedback.
Summary
A modern photonic device is very often an electronic device at the same time. It's not enough to design an ideal laser, modulator or photodiode — you have to check how the element works together with the driver, the amplifier, the RLC elements, and the rest of the circuit. OptiSPICE lets you analyse both domains in one environment, and it's especially valuable wherever the interaction between electronics and photonics determines how the device performs. In the overall design process, it sits between the model of a single component and the system: component → compact model → OptiSPICE → OptiSystem → measurement.
Manufacturer materials and illustrations
The product page includes a screenshot of the OptiSPICE environment and application examples: Optiwave – OptiSPICE
The OptiSPICE overview page includes illustrations of the BER Analyzer and the laser and fiber parameter-extraction tools: Optiwave – OptiSPICE Overview
The manufacturer's "Getting Started" guide with optoelectronic circuit examples: Optiwave – OptiSPICE Getting Started PDF