Time-Domain Terahertz - Toptica

Standard Package 850 / TeraBeam 1550DFB Lasers for cw Terahertz GenerationThe Standard Package offers the essential laser equipment for difference frequencygeneration in the terahertz range. It comprises two distributed feedback (DFB)lasers with built-in optical isolators, fiber-optic beam combination and low-noisedriver electronics. TOPTICA carefully selects the laser diodes with respect to theirmode-hop-free tuning range. Available at 850 nm and 1550 nm, the StandardPackage matches the excitation wavelengths of GaAs and InGaAs terahertzemitters, respectively.The TeraControl unit complements the package with computerized frequencytuning and lock-in detection of the terahertz photocurrent. A graphical interfaceconveniently sets or scans the terahertz frequency.Key features· Two DFB diode lasers with FPGAbasedfrequency control· Available wavelengths: 850 nm and1550 nm· Frequency accuracy 2 GHz absolute,10 MHz relativeThe workhorse for photomixingIn recent years, DFB diodes have developed into the workhorses for photomixing.DFB lasers offer robust mono-mode operation, wide continuous tuning andconvenient frequency control. The absence of alignment-sensitive componentsresults in a superior stability of output power and frequency.DFB lasers can be produced at virtually any near-infrared wavelength. The additionaladvantage of telecom-band diodes is their availability in highly integrated “butterfly”packages with miniaturized optics and a fiber pigtail. TOPTICA’s TeraBeam 1550uses these diodes.Applications· cw terahertz generation withGaAs photomixers (850 nm)· cw terahertz generation withInGaAs/InP photodiodes (1550 nm)DFB laser #1856Laser #1DFB laser #2PM fiber arrayWavelength (nm)854∆ν = 0 GHz∆ν = 2.1 THzSchematic of Standard Package.852Laser #20 10 20 30 40 50Temperature (°C)18 | www.toptica.comTemperature tuning of DFB lasers. The wavelengths of laser #1 and laser #2 match attemperatures of approximately 7 °C and 45 °C (shaded bar). By heating laser #1 andcooling laser #2, the difference frequency increases up to 2.1 THz. The TeraControlcalculates the precise temperature settings for any desired difference frequency.