A reference for working photonics engineers
Tutorials, references, and tools for the engineering of light.
Photonica covers the bench-level procedures that journal papers and vendor datasheets do not — laser characterization, photonic integrated circuit testing, and lab practice.
Tools
All tools →Laser characterization
T₀ Extraction Calculator
Fit characteristic temperature and pre-exponential from temperature-dependent threshold current data.
Laser characterization
Wall-Plug Efficiency Calculator
Compute WPE from LIV data point-by-point and find the peak operating current.
Optical alignment
Fiber Coupling Efficiency
Estimate Gaussian-beam to single-mode-fiber coupling from waist, MFD, and alignment offsets.
PIC characterization
Q to Propagation Loss
Convert intrinsic Q factor to waveguide loss, with presets for SOI, SiN, InP, and LNOI.
PIC design
Bragg Wavelength Calculator
Convert between grating period and Bragg wavelength for DFB/DBR lasers and integrated Bragg gratings.
Glossary
Full glossary →ABCDEFGHIJKLMNOPQRSTUVWXYZ
- Acceptance angle
- The maximum incidence angle at which light can enter an optical fiber or waveguide and still be guided. Geometrically related to the numerical aperture.
- Acousto-optic modulator (AOM)
- An optical device that diffracts and frequency-shifts light using an acoustic wave traveling through a transparent crystal. Used for laser intensity modulation, frequency shifting, beam deflection, and Q-switching.
- Amplified spontaneous emission (ASE)
- Broadband incoherent optical power produced by spontaneous emission events that are subsequently amplified by stimulated emission in an optical amplifier. The fundamental noise source in optical amplifiers.
- Auger recombination
- A non-radiative carrier recombination process in which the energy of an electron–hole pair is transferred to a third carrier rather than emitted as a photon. The dominant non-radiative loss in long-wavelength III–V semiconductor lasers.
- Avalanche photodiode (APD)
- A photodetector with internal carrier-multiplication gain via impact ionization in a high-field region. Provides higher sensitivity than PIN at the cost of multiplication noise and bandwidth-gain tradeoff.
- Balanced detection
- A photodetection scheme using two photodiodes with the difference of their photocurrents taken as the output. Cancels common-mode signals and noise, doubling sensitivity for coherent detection.
- Bandgap (energy gap, E_g)
- The energy separation between the top of the valence band and the bottom of the conduction band in a semiconductor. Determines the longest wavelength a material can emit or absorb.
- Beam quality (M²)
- The beam propagation ratio, comparing the divergence of a real laser beam to that of an ideal Gaussian beam of the same waist size. M² ≥ 1, with M² = 1 corresponding to a diffraction-limited beam.
Latest additions
All articles →- May 20, 2026Procedure · Detector characterizationPhotodetector Characterization: Responsivity, NEP, and BandwidthProcedures for measuring the three primary parameters of photodetectors used in photonics — wavelength-dependent responsivity, noise-equivalent power, and 3-dB electrical bandwidth — with focus on the standard measurement configurations for InGaAs PIN photodiodes.
- May 19, 2026Workflow · Laser characterizationDFB Laser Characterization: Full Parameter Extraction WorkflowComplete characterization workflow for a distributed-feedback (DFB) semiconductor laser, integrating LIV, spectral, temperature-dependent, and noise measurements to extract the parameters required for telecom and sensing applications.
- May 18, 2026Reference · InstrumentationOptical Spectrum Analyzers: Operating Principles and Measurement ConfigurationReference for optical spectrum analyzers (OSAs) including diffraction grating, Fabry-Pérot, and Fourier-transform variants, resolution bandwidth and dynamic range specifications, and the standard measurement configurations for laser source characterization, OSNR measurement, and EDFA gain characterization.
- May 17, 2026Procedure · Laser characterizationWall-Plug Efficiency from LIV MeasurementsProcedure for computing wall-plug efficiency (electrical-to-optical conversion efficiency) of a semiconductor laser from LIV data, with discussion of peak operating point, comparison with internal and external quantum efficiencies, and typical values across device classes.
- May 16, 2026Procedure · Laser characterizationSetting Up a Temperature-Controlled Laser Characterization BenchEquipment selection, thermal mounting, electrical configuration, and noise mitigation for a benchtop laser diode characterization setup, with focus on the configuration choices that determine measurement quality.
What you'll find here
§1 Tutorials
Step-by-step walkthroughs
Laser characterization, PIC testing, and measurement workflows. Worked examples and underlying data.
§2 Glossary
Precise definitions
Short entries for the terms photonics papers assume the reader already knows. Each entry links to deeper material.
§3 Tools
Interactive calculators
Common photonics math — T₀ extraction, fiber coupling, Bragg wavelength, WPE, Q-to-loss. Runs in the browser.