DSTMS Organic THz Generation Crystal

Overview

DSTMS is the sister crystal to DAST and is the emitter behind several of the highest peak terahertz fields reported from table-top systems. It combines very high second-order nonlinearity with spectral coverage from roughly 0.3 to 15 THz, and outperforms the classical inorganic emitters ZnTe and lithium niobate by a wide margin when driven from a suitable near-infrared pump.

Choosing between DSTMS and DAST

DSTMS converts marginally more pump energy into the terahertz band, so for a fixed pump it usually gives more terahertz energy. DAST radiates over a broader spectrum, which can translate into a higher instantaneous peak field even at slightly lower total energy, and it survives more pump fluence. Neither is universally better: pick DSTMS when total terahertz energy matters and DAST when bandwidth or damage headroom matters.

Pump requirements and geometry

DSTMS phase matches for pumps around 1.3 to 1.5 um and is compatible with telecom fibre sources, OPAs and OPCPAs. The geometry is collinear and mechanically simple: focus the pump onto the crystal, collimate the emerging terahertz beam with a gold off-axis parabolic mirror, and block the residual pump immediately after the crystal with black polyethylene or PTFE.

Handling and storage

Organic terahertz crystals are soft, hygroscopic and easily damaged. Store them sealed and dry, keep the mounted element inside a nitrogen or dry-air purge box during operation, and raise the pump fluence gradually while watching the terahertz signal rather than jumping straight to the target level. Never clean the crystal face with solvents, and always handle the part by its mount or substrate edge. Damage in organic crystals is usually cumulative rather than catastrophic, so a crystal that has been overdriven once will keep degrading.