Electro-optic modulator

• US 4,206,979 A
• Filed: 06/27/1978
• Issued: 06/10/1980
• Est. Priority Date: 03/28/1977
• Status: Expired due to Term

• Current Assignee: Grumman Aerospace Corporation (Northrop Grumman Corporation)
• Original Assignee: Grumman Aerospace Corporation (Northrop Grumman Corporation)
• Inventors: Jost, Steven R.
• Primary Examiner(s): Bauer, Edward S.
• Application Number:
  US05/919,471
• Time in Patent Office: 714 Days
• Field of Search: 350/342, 357/30
• US Class Current: 349/26
• CPC Class Codes: G02F 1/1354 having a particular photoconducting structure or material
• CPC Class Codes: Y10S 359/90 Methods

Abstract

A multi-heterojunction of one type of photoconductive layer with another type of photoconductive layer to provide back-to-back modulators using illumination to decrease a potential barrier for current flow and increase voltage drop across an electro-optic device therewith associated in reproduction of an image thereby.

Claims

1. In a transmissive electro-optical element comprised of an electro-optic film between alignment layers and a photoconductive layer located between a pair of transparent electrodes, the improvement wherein the photoconductive layer includes multiple n-type CdS photoconductors with a p-type CdS:

Cu photoconductor therebetween.

2. A transmissive incoherent to coherent image producer comprising:

multiple heterojunction means including two n-type CdS photoconductor layers sandwiching a CdS;

Cu photoconductor layer of p-type conductivity type;

transparent conductive electrodes, one of which is directly connected to the multiple heterojunction means and another of which is spaced therefrom;

electro-optic material in the space between the multiple heterojunction means and said another of said transparent conductive electrodes; and

means to generate a signal connected across said transparent electrodes.

3. A method of producing a light controlled AC electro-optic modulator, said method including the steps of manufacture of a multiple heterojunction comprising:

depositing a first layer of CdS photoconductive material of P-type conductivity on a transparent electrode;

heat treating said electrode with its deposited layer at a predetermined temperature to an inert atmosphere to crystallize said first layer of CdS;

depositing a thin layer of copper on the first photoconductor material;

depositing a second layer of CdS photoconductor material on said copper layer; and

heat treating the aforesaid at a predetermined temperature in an inert atmosphere to make a multiple heterojunction structure of two n-type CdS layers sandwiching a layer of p-type CdS;

Cu.