LDH-I Series Smart Picosecond Laser Diode Heads

Smart picosecond laser diode heads covering UV-A to NIR, providing the right combination of power, pulse width, and diode type for any time-resolved technique.

Pulse. Power. Precision.

The LDH-I Series is a versatile family of smart picosecond diode lasers designed for precise, calibrated excitation across UV-A to NIR wavelengths. Each laser head combines stable picosecond performance with automatic identification, stored calibration data, and seamless control when operated with the Taiko PDL M1 laser driver. With narrow-pulse, high-power, and tapered-amplified diode laser options, the LDH-I Series supports flexible pulsed laser operation for a broad range of microscopic and spectroscopic techniques, as well as photonic ranging methods such as LiDAR — making it an adaptable diode laser source for a wide range of time-resolved techniques.

Key Benefits

• Higher measurement accuracy — stable, calibrated pulse energy and shape across the full repetition rate range
• Faster data acquisition — repetition rates up to 100 MHz for high-throughput measurements
• Broad experimental flexibility — pulsed, burst, and CW operation from a single laser head
• Reliable synchronisation — automatic head identification and stored calibration when paired with Taiko PDL M1
• Improved experiment stability — hot-plug wavelength switching without powering down the driver
• Long-term consistency — power calibration and an operating hours counter built into every head

Smart Picosecond Excitation Across UV-A to NIR

Wavelengths from 375 nm to 1550 nm

LDH-I Series laser heads cover the spectral range from 375 nm to 1550 nm, including high-power multimode diodes in the visible and NIR, with 532, 561, and 594 nm heads available. Each head includes power calibration, and when paired with a Taiko PDL M1 driver, optical output power can be controlled in both pulsed and continuous modes, with wavelength calibration also available in CW mode.

Pulse Widths Down to 20 ps

All laser heads emit picosecond pulses with a full width at half maximum (FWHM) typically around 90 ps or below — with some heads capable of pulse widths down to 20 ps. Pulse width isn’t directly controllable but depends on the selected diode power level; at maximum intensity, pulse width can broaden.

Dual Calibration — Linear Mode and Max Power Mode

LDH-I laser heads are calibrated for two distinct operating modes:

Linear Mode for Stable Instrument Response

In linear mode, pulse energy and pulse shape remain constant across the entire repetition rate range for a given intensity setting. This guarantees a stable instrument response function (IRF) for applications such as lifetime measurements, with perfect linearity of average power at every repetition rate — doubling the repetition rate doubles the average output power.

Max Power Mode for Highest Pulse Energy

Max power mode reaches the highest achievable pulse energy at each repetition rate. The exact gain depends on the connected laser head and the operating repetition rate. In both modes, pulse energy increases linearly with the intensity setting (%).

Average optical output power is measured and stored in the laser head’s internal memory as calibration data across all repetition rates, typically between 1 MHz and 100 MHz, with CW mode power also calibrated. Achievable pulse energies range from tens of picojoules up to 2 nanojoules, corresponding to maximum average output powers of up to 150 mW at high repetition rates.

Repetition Rates up to 100 MHz

LDH-I laser heads operate from single shot up to repetition rates typically in the 100 MHz range, though the maximum depends on the individual diode. Some heads recommend a lower maximum (e.g. 60 MHz) to maintain constant pulse energy across the full repetition rate range.

Pulsed, Burst, and CW Operation Modes

Every LDH-I Series laser head supports three operation modes:

• Pulsed mode — constant repetition rate, commonly used for time-resolved measurements
• Burst mode — flexible bursts of pulses with a selectable pulse count and burst period, useful for measuring long lifetime decays, laser ranging, and specific seeding tasks
• CW mode — enables significantly higher average laser power

In materials science particularly, choosing the right operation mode — pulsed, burst, CW, or fast-switched CW — is key to unlocking accurate, insightful experimental results.

Seamless Compatibility with Taiko PDL M1

Automatic Head Identification & Stored Calibration

Paired with the Taiko PDL M1 laser driver, LDH-I heads become a fully calibrated excitation system. The driver automatically identifies each head, reads its stored power and wavelength calibration data, and keeps pulse energy and shape constant across the full repetition rate range in linear mode. The currently active lasing regime — spontaneous emission, short pulse, or broadened pulse — is shown on the driver’s local display with an intuitive colour code.

Hot-Plug Capable Wavelength Switching

LDH-I laser heads support hot plugging, meaning wavelengths can be swapped without powering down the driver — reducing experiment downtime when working across multiple excitation wavelengths.

Flexible Fibre Coupling

LDH-I Series laser heads can be optionally coupled into single-mode, multi-mode, or polarisation-maintaining single-mode fibres via a range of connector types. FC/APC connectors are recommended for most applications, as they minimise back reflections that can interfere with laser stability. Under typical conditions, coupling efficiencies exceed 40% for single-mode and 80% for multi-mode fibre. All fibre-coupled units are precisely aligned before delivery for stable output and consistent beam quality.

Laser Combining Unit for Multi-Colour Excitation

For multi-colour excitation, several LDH-FA laser heads can be combined into a single polarisation-maintaining fibre using PicoQuant’s Laser Combining Unit (LCU), enabling compact, flexible multi-wavelength excitation configurations.

• Wavelength range: 375 nm to 900 nm
• Up to 5 laser lines
• Polarisation-maintaining single-mode output fibre
• Flexible configurations

LDH-I in High-Rate TCSPC Measurements

High-speed TCSPC faces fundamental limits from pile-up and detector dead time, particularly in fluorescence measurements at high photon rates. Recent advances in hybrid photodetectors and correction frameworks now enable distortion-free lifetime analysis even beyond the excitation rate, opening the door to ultra-fast, high-precision time-resolved experiments using LDH-I laser heads.