Photocathode, electron tube, field assist type photocathode, field assist type photocathode array, and field assist type electron tube

A field assist type photocathode comprising:

• a light absorbing layer for absorbing incident light to generate photoelectrons;
• a first electrode formed on a side of a first principal surface of the light absorbing layer;
• and
• a second electrode formed on a side of a second principal surface of the light absorbing layer and, together with the first electrode, used for applying a voltage between the first principal surface and the second principal surface of the light absorbing layer;
• wherein the first electrode has a through hole penetrating in a thickness direction and a pattern according to a predetermined rule for inducing surface plasmon resonance is formed in a surface of the first electrode;
• and
• wherein the light absorbing layer absorbs light outputted from the through hole of the first electrode, to generate the photoelectrons, and emits the photoelectrons generated, through the through hole of the first electrode to the outside.

A field assist type photocathode array comprising a plurality of field assist type photocathodes,

• wherein each photocathode comprising:
• a light absorbing layer for absorbing incident light to generate photoelectrons;
• a first electrode formed on a side of a first principal surface of the light absorbing layer;
• a second electrode formed on a side of a second principal surface of the light absorbing layer and, together with the first electrode, used for applying a voltage between the first principal surface and the second principal surface of the light absorbing layer;
• wherein the first electrode has a through hole penetrating in a thickness direction and a pattern according to a predetermined rule for inducing surface plasmon resonance is formed in a surface of the first electrode;
• and
• wherein the light absorbing layer absorbs light outputted from the through hole of the first electrode, to generate the photoelectrons, and emits the photoelectrons generated, through the through hole of the first electrode to the outside;
• wherein the first and second electrodes of the field assist type photocathodes are adapted so as to be able to apply a voltage to each field assist type photocathode.

A field assist type electron tube comprising a field assist type photocathode,

• wherein said field assist type photocathode comprising:
• a light absorbing layer for absorbing incident light to generate photoelectrons;
• a first electrode formed on a side of a first principal surface of the light absorbing layer;
• and
• a second electrode formed on a side of a second principal surface of the light absorbing layer and, together with the first electrode, used for applying a voltage between the first principal surface and the second principal surface of the light absorbing layer;
• wherein the first electrode has a through hole penetrating in a thickness direction and a pattern according to a predetermined rule for inducing surface plasmon resonance is formed in a surface of the first electrode;
• and
• wherein the light absorbing layer absorbs light outputted from the through hole of the first electrode, to generate the photoelectrons, and emits the photoelectrons generated, through the through hole of the first electrode to the outside.

A field assist type electron tube comprising a field assist type photocathode array comprising a plurality of field assist type photocathodes,

• wherein each photocathode comprising:
• a light absorbing layer for absorbing incident light to generate photoelectrons;
• a first electrode formed on a side of a first principal surface of the light absorbing layer;
• and
• a second electrode formed on a side of a second principal surface of the light absorbing layer and, together with the first electrode, used for applying a voltage between the first principal surface and the second principal surface of the light absorbing layer;
• wherein the first electrode has a through hole penetrating in a thickness direction and a pattern according to a predetermined rule for inducing surface plasmon resonance is formed in a surface of the first electrode;
• and
• wherein the light absorbing layer absorbs light outputted from the through hole of the first electrode, to generate the photoelectrons, and emits the photoelectrons generated, through the through hole of the first electrode to the outside;
• wherein the first and second electrodes of the field assist type photocathodes are adapted so as to be able to apply a voltage to each field assist type photocathode.