1. A method comprising:
depositing a film of liquid crystal material in a solvent onto one or more surfaces;
orienting a polarization direction of the liquid crystal material; and
removing the solvent to leave a thickness of solid liquid crystal material sufficient to delay a first polarization component one-half wavelength relative to a second polarization component that is perpendicular to the first polarization component.
2. The method of claim 1, wherein the thickness of solid liquid crystal material is sandwiched between a first thin transparent substrate and a second thin transparent substrate.
3. The method of claim 1, further comprising:
propagating light through a first waveguide segment, the solid liquid crystal material, and a second waveguide segment;
amplifying the light in the first waveguide segment and in the second waveguide segment; and
providing feedback to form a laser.
4. The method of claim 1, wherein the thickness of solid liquid crystal material is deposited in a slot in a substrate, wherein the substrate has a waveguide, and wherein the slot is transverse to the waveguide between a fist waveguide segment and a second waveguide segment, and wherein the liquid crystal material swaps light having a first polarization orientation with light having a polarization orientation perpendicular to the first polarization orientation to compensate for a polarization-sensitive differential gain of the first and second waveguide segments.
5. The method of claim 4, wherein the first waveguide segment is substantially equal in length to the second waveguide segment, wherein the waveguide is formed substantially parallel to a surface of the substrate, and wherein a polarization component of light parallel to the surface of the substrate is swapped with a polarization component of the light perpendicular to the surface of the substrate of the substrate by the liquid crystal material.
6. An apparatus comprising:
a thin polarization converter that includes:
a thin first substrate that is substantially transparent to a wavelength of light; and
a birefringent material deposited on one or more surfaces of the substrate and oriented such that the polarization converter is substantially transparent to, and forms a half-wavelength birefringent plate for, the wavelength of light; and
a waveguide having a first segment and a second segment, wherein the polarization converter is placed between the first segment and the second segment to compensate for a polarization-sensitive differential gain of the waveguide.
7. The apparatus of claim 6, wherein the first segment is substantially equal in length to the second segment, wherein the waveguide segments are formed substantially parallel to a surface of the substrate, and wherein a polarization component of the light parallel to the surface of the substrate is swapped with a polarization component of the light perpendicular to the surface of the substrate by the polarization converter.
8. An apparatus comprising:
a thin polarization converter that includes:
a first substrate surface;
a second substrate surface; and
a liquid crystal material sandwiched between the first substrate surface and the second substrate surface such that the polarization converter is substantially transparent to, and forms a half-wavelength birefringent plate for, a wavelength of light; and
a waveguide having a first segment and a second segment, wherein the polarization converter is placed between the first segment and the second segment to compensate for a polarization-sensitive differential gain of the waveguide.
9. The apparatus of claim 8, wherein the first substrate surface is a major surface of a first thin substrate and the second substrate surface is a major surface of a second thin substrate.
10. The apparatus of claim 8, further comprising:
a gain medium; and
a feedback mechanism configured such that a light path through the gain medium, the polarization converter, and the feedback mechanism forms a laser.
11. The apparatus of claim 8, wherein the first segment is substantially equal in length to the second segment, wherein the waveguide segments are formed substantially parallel to a surface of a substrate, and wherein a polarization component of the light parallel to the surface of the substrate is swapped with a polarization component of the light perpendicular to the surface of the substrate by the polarization converter.
12. The apparatus of claim 8, further comprising a substrate having the waveguide formed therein, and having a slot transverse to the waveguide, wherein the first substrate surface is one face of the slot and the second substrate surface is an opposing face of the slot, and wherein the polarization converter is formed in the slot in the substrate by the liquid crystal material sandwiched between the faces of the slot.
13. The apparatus of claim 12, wherein the faces of the slot are pre-treated such that the liquid crystal material self aligns to an orientation that swaps a first polarization component of the light with a second polarization component of the light that is perpendicular to the first polarization component.
14. The apparatus of claim 12, wherein the waveguide includes a gain medium, the apparatus further comprising:
a feedback mechanism configured such that a light path through the gain medium, the polarization converter, and the feedback mechanism forms a laser.
15. The apparatus of claim 12, wherein the first segment is substantially equal in length to the second segment, wherein the waveguide is formed substantially parallel to a surface of the substrate, and wherein a polarization component of the light parallel to the surface of the substrate is swapped with a polarization component of the light perpendicular to the surface of the substrate by the polarization converter.
16. A method comprising:
passing light through a first waveguide segment that differentially changes an amplitude of the light relative to a first polarization orientation;
passing the light through a thickness of oriented liquid crystal material sufficient to delay a first polarization component one-half wavelength relative to a second polarization component that is perpendicular to the first polarization component, wherein the first polarization component is at a forty-five degree angle to the first polarization orientation; and
passing the light through a second waveguide segment that differentially changes the amplitude of the light based on the polarization orientation.
17. The method of claim 16, wherein the thickness of oriented liquid crystal material is sandwiched between a first thin transparent substrate and a second thin transparent substrate.
18. The method of claim 16, further comprising:
amplifying the light in the first waveguide segment and in the second waveguide segment; and
providing feedback to form a laser.
19. The method of claim 16, wherein the liquid crystal material swaps light having the first polarization orientation with light having a polarization orientation perpendicular to the first polarization orientation to compensate for a polarization-sensitive differential gain of the first and second waveguide segments.
20. The method of claim 19, wherein the first waveguide segment is substantially equal in length to the second waveguide segment, wherein the first and second waveguide segments are formed substantially parallel to a surface of a substrate, and wherein a polarization component of the light parallel to the surface of the substrate is swapped with a polarization component of the light perpendicular to the surface of the substrate.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for rendering subject information for a protected message received and stored at an electronic communications device, wherein the protected message has been protected at an originating sender’s device and is initially received by the electronic communications device without subject information, the method comprising:
extracting selected information from the protected message; and
storing the selected information on the electronic communications device as subject information for the protected message.
2. The method of claim 1, comprising:
generating on a display of the electronic communications device a message list including a subject display field for subject information for each of a plurality of messages stored on the electronic communications device including the protected message, wherein if the subject information for the protected message is stored on the electronic communications device when the display is generated, including at least part of the stored subject information in the subject display field for the protected message.
3. The method of claim 1 wherein entry of a shared secret by a user is required to open the message, the method comprising detecting that the protected message has been opened following successful entry of the shared secret and wherein the selected information is extracted from the protected message after the protected message has been opened.
4. The method of claim 3 wherein the selected information is extracted from the protected message only the first time that the protected message is opened at the electronic communications device.
5. The method of claim 3 wherein the protected message has been encrypted at the originating sender’s device, the method comprising decrypting the protected message after entry of the shared secret.
6. The method of claim 5 wherein the protected message that is received at the electronic communications device has been further encrypted at a location intermediate the originating sender’s device and the electronic communications device, the method further comprising decrypting the received protected message at the electronic communications device to reverse the encryption applied at the intermediate location.
7. The method of claim 3 including prior to an opening of the protected message: displaying information about the protected message in a message list on a display of the electronic communications device and providing a prompt to the user to provide the shared secret upon receiving a user input indicating selection of the protected message from the message list for opening.
8. The method of claim 2 wherein electronic communications device is a mobile device enabled to exchange messages over a wireless network, and wherein the generating of the message list is carried out in response to a user input to the electronic communications device and if no subject information is stored on the electronic communications device for the protected message when the message list is generated, then a predetermined phrase indicating that the protected message is protected is displayed in the subject display field for the protected message a predetermined phrase indicating that the protected message is protected.
9. The method of claim 1 wherein the protected message received at the electronic communications device has been protected at the originating sender’s device through encryption, an electronic signature, or through an encryption and electronic signature in compliance with either SMIME or PGPMIME.
10. The method of claim 1 wherein the protected message is an email message that is received at the electronic communications device without subject information, and includes a message body portion that contains text, and the selected information is at least partially selected from the text contained in the message body portion based on predetermined selection criteria.
11. The method of claim 10 wherein predetermined character combinations in the text are excluded from the selected information.
12. The method of claim 1 wherein extracting the selected information is performed once the protected message is received at the electronic communications device.
13. The method of claim 1 wherein extracting the selected information is performed after a user input to the electronic communications device requesting that a message list that includes subject information for a plurality of messages be generated.
14. An electronic communications device enabled to receive electronic messages, the device including:
a display;
a communications subsystem for receiving messages from an external source;
storage for storing messages received through the communications subsystem;
a user input device;
a messaging client for processing messages received by the device through the communications subsystem, the messaging client comprising a subject rendering module for extracting information from protected messages that are received at the device without subject information and storing the extracted information on the storage.
15. The device of claim 14 wherein the messaging client is configured for displaying on the display a message list identifying messages that are available to be viewed on the device, the message list including a subject display field for displaying subject information for the identified messages, and wherein the stored extracted information for respective protected messages is used in the subject display field when the protected messages are identified in the message list.
16. The device of claim 15 wherein at least some of the protected messages are sender encrypted and user input of a shared secret is required to decrypt and open the sender encrypted protected messages, wherein the subject rendering module is configured for extracting the selected information from a sender encrypted protected message only after the sender encrypted protected message has been decrypted following user input of the shared secret.
17. The device of claim 16 wherein if no subject information is stored on the electronic communications device for a listed protected message when the message list is generated, the messaging client is configured to display in the subject display field for the listed protected message a predetermined phrase indicating that the listed protected message is protected.
18. The device of claim 16 wherein the messaging client is configured for, prior to an opening of a listed protected message identified in the message list, providing a prompt to the user to provide the shared secret upon receiving a user input through the user input device indicating selection of the listed protected message from the message list for opening.
19. The device of claim 14 wherein protected messages consist of messages that have been encrypted, signed, or signed and encrypted, at an originating sender’s device.
20. A computer program product having a computer readable medium storing a instructions for rendering subject information for a protected message received and stored at an electronic communications device, wherein the message is initially received by the electronic communications device without subject information, the instructions including code means for executing the method of claim 1.