Modes of Operation in Laser Technology

on 09/01/2023

The coherence of lasers distinguishes them from other light sources. The output of spatial (or transverse) coherence is usually a narrow, diffraction-limited beam. Laser beams can be concentrated in very small areas for high irradiance, or they can have very low divergence for concentrating power over a long distance. A laser differs from other light sources in that it emits coherent light. Laser cutting and lithography are made possible by spatial coherence, which allows a laser to be focused to a small area. Spatial coherence also allows a laser beam to remain narrow over long distances (collimation), making laser pointers and lidar possible (light detection and ranging).
Lasing usually starts with spontaneous emission into the lasing mode in most lasers. This original light is subsequently amplified in the gain medium by stimulated emission. In terms of direction, wavelength, and polarisation, stimulated emission produces light that is identical to the input signal, but the phase of the emitted light is 90 degrees ahead of the stimulating light. This, together with the optical resonator’s filtering function, provides laser light its distinctive coherence and, depending on the resonator’s design, may also give it uniform polarisation and monochromaticity. Depending on whether the power output is largely continuous across time or if it takes the form of light pulses on one- or another-time scale, a laser can be categorized as either continuous or pulsed. Of course, even a laser whose output is generally continuous can be turned on and off at a certain rate to produce light pulses.
Some laser applications require a beam with a constant output power throughout time. Continuous-wave (CW) lasers are one type of laser. To meet this need, a variety of lasers can be made to operate in continuous-wave mode. Many of these lasers lase in multiple longitudinal modes at once, and beats between the slightly different optical frequencies of those oscillations will produce sufficiency minor departure from time scales more limited than the full circle time (the proportional of the recurrence separating between modes), commonly a couple of nanoseconds or less. In other circumstances, the application necessitates the generation of pulses with the highest energy achievable. Because the beat energy is equivalent to the typical power partitioned by the reiteration rate, this objective can some of the time be fulfilled by slowing down the rate of pulses so that more energy can be stored between them. Another way to achieve pulsed laser operation is to pump the laser material with a pulsed source, either through electronic charging in the case of flash lamps or by using another pulsed laser. In the past, dye lasers used pulsed pumping because the inverted population lifespan of a dye molecule was so brief that a high-energy, quick pump was required.
By reducing or killing tumors or precancerous growths, lasers are employed to treat cancer. They’re most typically utilized to treat tumors that are found on the body’s surface or in the lining of internal organs. They’re used to treat basal cell skin cancer, as well as the early stages of cervical, penile, vaginal, vulvar, and non-small cell lung cancer. Fiber lasers have a fundamental constraint in that the light intensity in the fiber cannot be so high that optical nonlinearities caused by the local electric field strength become dominant, preventing laser operation and/or leading to fiber material damage.
Stimulated emission, in which energy is taken from a transition in an atom or molecule, is the mechanism by which a laser produces radiation. Albert Einstein predicted this quantum phenomenon when he derived the link between the A coefficient, which describes spontaneous emission, and the B coefficient, which describes the absorption and stimulated emission.n

Climate Change moot recommends storing rainwater underground

on 09/01/2023

A national conference on Climate Change has recommended that harvested rain should be used for groundwater recharge through groundwater recharge hotspots using Bhungroo Technology in Sindh.
Also, the moot emphasized upon rainwater harvesting through the construction of small dams in potential areas such as Karoonjhar, Kirthar Mountain range, and Ubhan Shah Hills should be taken on priority.
Titled, Integrating Climate Smart Agriculture, Water, Energy and Food Nexus for Sustainable Development and Food Security under Changing climate, this two-day conference was jointly organized by Dawood University of Engineering and Technology (DUET), Karachi, and Sindh Agriculture University (SAU), Tando Jam had detailed presentation and debate on every aspect of climate change.
The final recommendations read as under:
Zero tillage technology, mulching, furrow irrigation, and raised bed technology should be propagated and encouraged in irrigated areas of Sindh to achieve the targets of SDGs 1 and 6.
Agriculture should be strengthened and promoted in the untapped /dry areas of Pakistan, especially in the Cholistan, Kachoo, Kohistan, and Thar desert, by introducing Hi-Tech and supper irrigation methods
Rainwater harvesting through the construction of small dams in potential areas such as Karoonjhar, Khirthar Mountainous range, and Ubhan shah hills should be taken on priority.
Smart Agricultural Farms equipped with Precision Agriculture practices, IoT, and drone technology be introduced to enhance the quantity and quality of agricultural production, and Farmers should be supported in the transformation of traditional agriculture into smart agriculture
The role of wetlands should be considered for rainwater harvesting and flood mitigation apart from its role in the ecosystem and environment.
Harvested rain should be used for groundwater recharge through groundwater recharge hotspots using Bhungroo Technology.
Pakistan should promote energy conservation, increase energy efficiency, and on-farm solar, wind, and other renewable energy production as ways to mitigate agricultural greenhouse gas emissions and increase resiliency
Pakistan should promote farm scape that supports resilience to a changing climate and promotes carbon sequestration in woody biomass and soils.
Mangrove plantations along the entire Pakistan coast should be promoted and supported to work as a natural barrier against cyclones, seawater intrusion, storm surges, coastal erosion, etc.
40 years old Agroecological zones should be redefined considering the current climate change scenario
Conjunctive use of canal and drainage water should be supported, and farmers should be trained in the use of blended water for crop production
GIS, Remote Sensing, and Satellite Technology should be used for monitoring, mapping, and early cropped area yield estimations. To cope with the shortage of human resources in GIS & RS, related departments should be opened in HIES
Farmers should be encouraged for organic farming to avoid human health hazards associated with the use of chemicals in agriculture
Efforts should be taken to minimize the Climate Change impacts on Pakistan, especially on Sindh, by promoting forestation, curtailing Green House Gas (GHG) emissions, and protecting wetlands and rangelands
Policies for Water and Climate Change should be developed, approved, and adopted with gist and spirit.
Crop water productivity should be enhanced to a level of developed countries through research and the adoption of innovative technologies.
Encroachments within the riverbed should be removed for uninterrupted flow of the Indus during the monsoon period.
Governance issues in the water conveyance and delivery system should be improved so that farmers at the tail end of the system should get their due share of irrigation water.
The drainage plays a vital role to cope with urban and agricultural flooding. Hence, the drainage network in Sindh should be improved by the strengthening of LBOD and RBOD spinal drains as well as associated main and sub-drains.
Integrated Water Resources Management for water governance and management must be adopted at all levels.
The Federal and Provincial Governments should enhance the budget for research focusing on issues related to climate change, water, livestock, and food security.
The Indus delta should be the priority of the government in solving the freshwater availability, seawater intrusion, groundwater contamination, storm surges, cyclones, poverty, soil salinity & waterlogging issues of the delta
Agri. Tourism should be patronaged. For this, model farms should be opened in each district
As an acknowledgment of the importance of the Manchar wetland in Pakistan, it is recommended that it should be declared a “Ramsar site”

Importance of Air Conditioning, Significant Role on Energy & Global Warming

on 06/01/2023

This article will spread out the importance of we all use Airconditioning, Heating, and Refrigeration in our daily lives such as Offices, Houses / Apartments, Gym, Shopping Malls, Hospitals, Airports, Pharmaceuticals, Vehicles, other industries, small and medium enterprises as well as storage facilities keep fresh and healthy Foods, Sea Foods and Medicine i.e. Meat, Vegetables, Vaccines, etc.
Projections by the International Energy Agency (IEA) predict an increase to 5.5 billion units globally by 2050. Fatih Birol, Executive Director of the IEA warns that: the “Growing demand for air conditioners is one of the most critical blind spots in today’s energy debate”. He adds that an essential and relatively simple step is for governments to set higher efficiency standards for cooling. Energy demand due to air conditioning is expected to almost triple by 2050.
HVACR defines Heating, Ventilation, Air Conditioning, and Refrigeration plays a vital role as follows:
To provide comfort for people and industrial applications.
To provide better Indoor Air Quality (IAQ).
To preserve the foods (Meat, Sea Food, Vegetables, and Fruits) & Medicine.
To reduce the Energy requirement.
To minimize the Global Warming or Hot Climate Change effect.
The cooling industry is important, but it is also incredibly polluting – accounting for around 10% of global CO2 emissions. That is three times the amount produced by aviation and shipping combined. And as temperatures around the world continue to rise due to climate change, the demand for cooling will increase too.
First, we agree that Air Conditioning and Refrigeration is being used everywhere. As the population and awareness will more means demand of energy will increase day by day. So, Let’s focus on Energy mostly electricity.
Globally Energy Conservation and Climate Change – we are talking about.
Everyone is part to help the local society, provinces/states, and national levels, and combined efforts will help the globe. These will be discussed in detail.
The demand for Energy can be reduced if buyers both home appliances & commercial / Industrial people select the right and third-party Energy Certified Equipment.
Do buy energy efficient equipment which requires less electricity to meet the demand.
Do take valuable advice from an airconditioning expert for houses.
Do proper designing for Medium or Large-Scale Projects.
Do select the location of the Equipment for Split Air conditioners.
05.Do proper insulation on refrigerant pipes, walls / roof.
06.Do proper Installation and Commissioning.
07.Do preventive maintenance like filter cleaning.
08.Do select the professionals / experts for repairing / replacement and new installation.
The second most important factor is Global Warming & Ozone Depletion Layer. Air conditioners are terrible for the environment, which is complicated by the fact that they’re increasingly necessary as outside temperatures increase.
In China, a searing heat wave has lasted for more than two months, and the power grid is straining as people crank up their air-conditioning.
But as the planet keeps getting hotter, and more people around the world can afford to air-condition, its use is growing everywhere. By the middle of the century, there are likely to be about 5.6 billion appliances, and nearly triple the energy demand for cooling today.
“I think the numbers come out to about 10 new air conditioners every second for the next 30
years,” says Jack Alvarenga, a research scientist at Harvard University’s Wyss Institute, and part of a team working on redesigning how homes can be cooled.
The problem is significant both because of the amount of energy that air conditioners require and
the fact that current refrigerants, the chemicals that absorb the heat in your AC, are also potent greenhouse gases. (Thanks to the global Kigali Agreement, the worst refrigerants are being phased out, but that will take time.) The more AC is used, the hotter it will get outside.
HVAC System uses refrigerants (Gases) which absorb heat and provide cooling.
These refrigerants escape from the system and damage both Global Warming & Ozone Depletion Layer.
HFC emissions cause increased warming in the stratosphere, reports NASA, speeding up the chemical reactions that destroy ozone molecules and decreasing ozone levels.
In other words, HFCs trap heat in our atmosphere and contribute to global warming. Thus, they have high global warming potential (GWP) and are ultimately bad for the environment.
New Refrigerants – HFOs have zero ODP (Ozone Depletion Potential) and low GWP, making them a more environmentally friendly option than HFCs. HFOs don’t trap heat in our atmosphere and don’t contribute to global warming.
NOTE:
Glaciers start melting, rising sea levels, high precipitation, and change in climate globally due to high ambient temperature because of Global Warming.
The high demand for electricity means more emissions of Carbon Dioxide into the Environment. In addition to this, high electric bills.
Transitioning from HFC to HFO or HFO blends (New Refrigerants used in Cars, Fridges, Split Units, and Commercial Units) is an essential step in reducing the climate impact of the building and roofing industry.
Global warming is gauged by the increase in the average global temperature of the Earth. Along with our currently increasing average global temperature, some parts of the Earth may actually get colder while other parts get warmer—hence the idea of average global temperature. Greenhouse gas-caused atmospheric heating and agitation also increase the unpredictability of the weather and climate and dramatically increase the severity, scale, and frequency of storms, droughts, wildfires, and extreme temperatures.
90 percent reduction of HCFCs in developed countries. Developed countries are eliminating 90 percent of their HCFC production and consumption as per the schedule.
Montreal Protocol Adoption
The Montreal Protocol is adopted on 16 September 1987. The day is marked globally as the International Day for the Preservation of the Ozone Layer since 16 September 1995.
2016 – Kigali Amendment adopted as Parties adopt the Kigali Amendment to the Montreal Protocol on 15 October, agreeing to phase down the consumption and production of hydrofluorocarbons (HFCs).
Healing of ozone layer confirmed in 2013:
The scientific assessment of ozone depletion in 2014 confirms that the ozone layer is healing and will return to pre-1980 levels by mid-century, thanks to actions taken by Parties under the Montreal Protocol.
Conclusion:
Nowadays, providing cooling to everyone who needs it, and not just those who can afford it. This is a necessity instead of a luxury.
Air conditioning is the need of people to maintain a comfortable indoor environment. During Covid 19, the use of Airconditioning is more important, especially in public places. Earlier it was discussed – Airconditioning is the name of Cooled Air Only. In the current scenario, the importance is much bigger that will significantly improve in many areas of our lives.
As we all know that Pakistan is suffering a lot due to global warming and bearing serious consequences. This is the time to emphasize the importance of air conditioning, energy efficiency, and its effect on climate.
Hybrid System can be one way to reduce the use of Airconditioning at peak load means natural ventilation, evaporative cooling, and Mechanical Airconditioning.
The Use of Energy Efficient Air Conditioners and New Refrigerants will minimize the energy crisis, and global warming effect as well as the healing of the ozone depletion layer.
Pakistan Governmentescalates working relations with International Organization for Environment / Climate Change to spread out awareness of new refrigerants and do seminars all over Pakistan through Engineering Council and Pakistan HVACR Society etc.
Both Government and Industrial Sector should form the committee and prepare the guidelines and make sure to implement (both penalty or reward) in all areas. All professionals, scientist and scholars must take a step forward and emphasize on use of renewable energy and highlights the benefits of Energy Efficient Equipment & use of new refrigerants.
We should promote clean energy on small and large scales like solar or wind power energy. By acting responsibly now, we get to experience and preserve for ourselves and future generations the opportunity to survive and thrive and experience a sustainable prosperity.
Getting others aware of the real urgency of the climate and global heating emergency is the absolute least anyone can do to do their part to help themselves and humanity. Reducing Global Warming is huge task, and we should discuss at all forums and work as a community to save the world.
Actions should be taken to reduce Carbon Emissions and helps to reduce Global Warming:
Use Energy Efficient Air Conditioning & Refrigeration Equipment.
Use New Refrigerants for household items, Commercial & Industrial Projects.
Go paperless.
Use Electric Vehicle or Hybrid.
Make your home more energy and water efficient.
Use renewable energy resources (Solar, Wind, etc)
Recycling of Waste
Go Plastic Free
Increase the plants in the surrounding.
Besides, all media – Print Media (Newspapers, Magazines), Broadcast Media (TV, Radio), Outdoor or Out of Home (OOH) Media, and Social Media be part of this important awareness. All stakeholders work together to give awareness in order to save the next generation of Pakistan.n

Forms and Applications of Nanolasers

on 06/01/2023

Nanolasers, like conventional lasers, are based on Einstein’s stimulated emission theory; the key distinction between nanolasers and ordinary lasers in terms of mechanism is light confinement. To achieve light confinement, the resonator or cavity plays a crucial role in selecting the light with a specific frequency and direction as the most important amplification and suppressing the other light. A Fabry–Pérot cavity with two parallel reflection mirrors is used in conventional lasers. A microdisk laser is a miniature laser that consists of a disc with quantum well structures embedded in it. Its dimensions might be either micro or nano-scale. A whispering-gallery mode resonant cavity is used in microdisk lasers.
Periodic dielectric structures with various refractive indices are used in photonic crystal lasers, and light can be contained using a photonic crystal microcavity. There is an organized spatial distribution in dielectric materials. The Fano resonance phenomenon occurs when a flaw in the periodic structure causes the two-dimensional or three-dimensional photonic crystal structure to confine the light in the space of the diffractive limit, resulting in a high-quality factor and strong light confinement for lasers. The plasmonic nanolaser is a nanolaser based on surface plasmon that has a size that much exceeds the diffraction limit of light. When a plasmonic nanolaser is nanoscopic in three dimensions, it is also known as a spacer, because it has the smallest cavity and mode size. At this time, designing a plasmonic nanolaser is one of the most effective technology methods for laser shrinking. Nanowire lasers made of semiconductors have a semi-one-layered structure with breadths going from a couple of nanometers to two or three hundred nanometers and lengths going from many nanometers to a couple of microns.
In recent years, new types of nanolasers have been produced that approach the diffraction limit. In a coupled cavity system, parity-time symmetry is related to a balance of optical gain and loss. The phase transition of lasing modes happens at an extraordinary moment when the gain–loss contrast and coupling constant between two identical, closely positioned cavities are controlled. A Fabry–Pérot cavity with two parallel reflection mirrors is used in conventional lasers. The light could be restricted to a maximum of half its wavelength in this situation, and this limit is known as the diffraction limit of light. Improving the reflectivity of the gain medium, such as employing photonic bandgap and nanowires, is one strategy to approach or decrease the diffraction limit of light. Converting light into surface plasmons in nano-structuralized metals for cavity amplification is another viable technique to exceed the diffraction limit.
The enhancement effect in non-linear optics or surface-enhanced-raman-scattering is also possible with such a laser’s powerful optical fields (SERS). The Internet is growing at a breakneck pace, consuming e normous amounts of energy in the process. Plasmonic nanolaser sensors that can detect certain molecules in the air and be utilized for optical biosensors have recently been developed. Nanolasers have considerable potential for practical applications in the fields of materials characterization, integrated optical interconnects, and sensing due to their unique features, which include low lasing thresholds, high energy efficiency, and rapid modulation speeds. Although nanolasers have shown significant promise, there are still certain obstacles to their widespread application, such as electrically injected nanolasers, cavity layout engineering, and improved metal quality. Realizing electrically injected or pumped operation at room temperature for nanolasers is a critical step toward their practical implementation. However, the majority of nanolasers are optically pumped, and electrically injected nanolasers are still a major technical problem.n

IEEE R10 EA LOCAL INITIATIVE PROGRAM
Focusing tools, free online facilities for educational facilitation

on 06/01/2023

A 2-Day workshop was organized by IEEE educational activities, Karachi section in collaboration and with IEEE Computer Society (Karachi section. The workshop was organized by Dr. M. Sadiq Ali Khan Chair IEEE Educational Activities, Karachi Section, coordinated and conducted by the key resource persons: Muhammad Taha Hassan (Member IEEE Education Society) and Muhammad Hammad Hassan (Member IEEE Computer Society).
The objective of this workshop was to bring about awareness in students and teachers alike about tools and free online facilities available for educational facilitation. Various areas of Karachi are underdeveloped currently and books and physical resources are becoming increasingly expensive, making it difficult to sustain education in underprivileged schools.
Approximately 70 participants were present, 60 of which were teachers of Primary and secondary level students, and the rest were their teachers who attended. The tools and sites discussed were easily accessible and crucial in this day and age, such as Google, Gmail, Web browsers, GetEpic, Blooket, Khan Academy, TEDEd, and many more. With overwhelmingly positive feedback from the students, teachers, and the School principal alike, the objective of this workshop to inspire motivation and bring about awareness of digitally accessible tools was deemed complete as it came to a close on 20th August 2022.
During the event, the school was visited by the esteemed Dr. Muhammad Aamir Chair IEEE Communication Society, Karachi section, and Professor at SSUET, Karachi, who motivated and congratulated the school staff and resource persons involved in making the event a success. His recognition of everyone’s efforts boosted the morale of the participants as well as the volunteers and workers involved. The school’s principal, Mrs. Fouzia Saad also addressed the staff and her students, her kind gestures, valuable insights, and welcoming hospitality were well-received. Everyone was inspired to look up to a role model like her. With Dr. M. Sadiq Ali khan’s elevating address and certificate distributions, the workshop came to an end, and the participants learned a lot that they could use to improve their quality of education.
Program goals:
To improve the standard of education that the schools in underdeveloped areas are providing
by training the teachers and equipping them with more knowledge to handle the classroom better.
To provide the students of such schools with a drive for utilizing the internet efficiently,
pushing them one step closer to becoming life-long learners.
To give awareness to school owners and discuss with them the ways their school can become
more internet-dependent while not imposing too many internet requirements on the students.
To serve the community in such underdeveloped areas by providing them with an alternative to the expensive learning materials they require for better education, that they can access easily from their mobile phones.
To improve, as a whole, Karachi’s educational standard by introducing IEEE Education
activities as a learning platform to many schools that may not be aware of it yet.n