[Description]

The fiber coupled terahertz transmitter and detector provided by TERAVIL are designed for broadband operation and can be used in the standard time domain.

Based on the wavelength of the pump laser, low-temperature grown GaAs (LT GaAs) or GaBiAs can be used as photoconductors. The material has excellent sensitivity and a detectable wavelength range of approximately. 800 nm and 1060 nm have electron lifetimes shorter than 1 ps. As a result, ultra short half cycle THz pulses with a wide spectrum up to 5 THz can be generated and detected. The transport of pump bundle fibers eliminates time-consuming adjustments and ensures maximum experimental flexibility. For example, this feature allows for quick and convenient switching between different geometric shapes: transmission, reflection, etc. The terahertz transmitter and detector are installed in a compact housing compatible with a standard 1-inch optical bracket (Figure 1). Check the performance of each device and provide customers with technical passports, including test reports.

[Features]

• Based on LT GaAs or GaBiAs photoconductive materials

• Optimized for wavelengths around 800 nm or 1060 nm

• Wide spectral range and low noise

• Accompanying technical passport and test report

【 Application Fields 】

• Time resolved broadband terahertz spectroscopy

• Optical Pump THz Probe Spectroscopy

• Suitable for all fiber system solutions

Figure 1. FC Emitter (or detector) installed on a 1 "optical bracket

Integrated silicon lens

The terahertz transmitter and detector are equipped with an integrated hyper hemispherical lens made of high resistivity silicon, which is connected to PCA to improve the radiation efficiency of terahertz waves into free space. TERAVIL offers two standard types of lenses: for collimated or divergent terahertz beam output. The advantage of collimated terahertz beam output is that it is easy to set up, as there is no need to add optical components between the terahertz transmitter and detector in the experiment. However, this design has a large spherical aberration of terahertz beams, which can affect focusing. In the second scenario, the design of the lens assumes that PCA is located at a non planar point, which greatly reduces spherical aberration. As a result, almost diffraction limited spot of terahertz beams can be achieved.

Photoelectric Conductive Antenna (PCA)

A photoconductive antenna is specifically designed for terahertz transmitters or terahertz detectors. The substrate of GaAs contains an etched GaBiAs epitaxial active layer to achieve high dark resistance. The high photosensitivity of the material allows for the use of low average power light pulses for excitation. A coplanar Hertzian type dipole antenna structure was formed on its surface using AuGeNi metallization technology (Figure 2). The gap between metal contacts is similar to the diameter of a laser spot in the case of a detector, but larger in the case of an emitter. The photoconductive chip is installed on the PCB and placed inside the metal casing of the device. The SMA socket on the back of the housing is used to connect DC or AC bias to the THz transmitter, or to connect the input of the lock-in amplifier to the THz detector.

Figure 2. Microstrip antenna diagram: (a) transmitter, (b) detector (all dimensions are in micrometers)

Optical Fiber

TERAVIL provides zero dispersion optical fibers. In this type of fiber, femtosecond pulses maintain their form and the pulse duration does not differ significantly between the input and output of the fiber. Laser radiation is transmitted through FC/PC fiber optic connectors. It uses lenses fixed inside the terahertz transmitter and terahertz detector housing to focus onto PCA.