| 摘要 |
An emitter for emitting radiation in a first range of frequencies comprising: a photoconductive material ( 11 ); and first and second contact elements ( 12, 13, 14 ) separated by a photoconducting gap provided by said photoconducting material ( 11 ), for applying a bias across said photoconducting gap, wherein at least one of said first and second contact elements ( 12, 13, 14 ) comprises a resistive element ( 14 ) for restricting current flow between said first and second contact elements in a second range of frequencies lower than the first range of frequencies. |
